Driver Expectations When Navigating Complex Interchanges

Chapter 3. Task 4-Gather Feedback from Drivers

The overall objective of task 4 was to collect qualitative information about driver expectations from drivers in accordance with the methods outlined in the task 3 protocol. Twelve focus groups in three metropolitan areas (Seattle, WA; Columbus, OH; and Washington, DC) were used to obtain driver opinions, thoughts, and beliefs about their expectations in complex interchange scenarios. In particular, the specific objectives of the focus groups were to obtain information about the sources of expectation-related problems that drivers encounter and the kinds of remedies that drivers suggest for these problems. This includes aspects such as what makes drivers comfortable or uncomfortable in certain interchange scenarios. These objectives were addressed by having participants view video footage of a vehicle navigating a complex interchange and asking them questions and engaging them in discussions at various points during the video. An effort was also made to obtain information that could be used in future project tasks. This included asking drivers about their general strategies when navigating interchanges, specific actions they take, what type of information they look for when making certain decisions, and when and where they seek this information.

This chapter contains the following three technical sections:

• Task 4 Methods: Provides information about the focus group participants, procedures, materials, selected interchanges, and data analysis plan.
• Task 4 Results: Contains the results of the warm-up activity and summaries of all of the scenario discussions.
• Task 4 Conclusions: Discusses the main trends that were observed during the focus group sessions.

Task 4 Methods

This section describes the methods used to conduct and analyze the focus group data.

Participants

This section describes the general approach for selecting focus group locations and defining the participant demographic make-up of each session as well as the recruiting methods.

Focus Group Locations

The general approach for determining the focus group locations was to select locations that had large urban populations serviced by major freeway interchanges. Resources were set up to support participant recruitment and conduct the focus groups. This approach helped lower costs and reduce risks associated with having to conduct these activities remotely. Based on these requirements, the selected focus group locations were Seattle, WA; Washington, DC; and Columbus, OH. Four focus group sessions were held in each location.

Demographic Sampling Objectives

Each focus group session was comprised of up to 12 licensed adult drivers². Individual focus group sessions were open to drivers of all age groups; however, researchers tried to balance age and gender in each. In particular, an approximately equal number of males and females was scheduled from each of the young (< 30), middle (30-55), and older (55+) driver age groups. Table 4 shows the actual demographic composition of the sessions.

Table 4. Demographic composition of each focus group.

Print and online advertisements were the primary methods for recruiting drivers. Specifically, recruitment advertisements were posted in the following sources as needed: Craigslist^®, local newspapers, and the contractor's driving study recruitment Web site.

One concern with the focus groups was that the number of participants in each session was expected to be relatively small (nine or less as originally planned). Small sessions run the risk of having a reduced diversity of viewpoints. This issue was addressed in two ways. The first was to include a mix of driver ages and genders in each session to promote differences in driving experience and strategies. The second was that group discussions were supplemented with individual written responses to key interchange driving questions. This provided additional data and reduced data transcription requirements.

Procedures and Materials

The primary data collection activity was the discussion of interchange scenarios using a dynamic scenario presentation (video-based), including individual discussion questions in a scenario response booklet. The following sections describe the primary data collection methods and corresponding materials that were used to present the focus group stimuli.

Dynamic Scenarios

The dynamic scenario approach involved a video-based depiction of a single drive/maneuver through an interchange which started well in advance of the interchange and ended some time after the maneuver was compete. This approach is described in more detail in the following sections.

General Approach

Dynamic scenarios involved participants viewing a video recording of a drive through an interchange. The moderator introduced the activity by explaining to the participants that they would be viewing a video of interchange driving. Each scenario began with participants being given an overview of the driving objectives for the scenario and any other relevant context.

The same video scenario was shown to participants three times. The first time was used to collect individual responses from participants without a group discussion. Specifically, participants were shown the scenario video, which was paused at key points in the drive (referred to as "critical points" (see figure 3)). These critical points corresponded to times or locations in which drivers needed to make key decisions, where they may have had difficulty, or where their expectations were of particular interest (e.g., after viewing a guide sign). During these pauses, participants were asked questions, and they wrote down answers individually. The response booklet used in this activity is provided in appendix A. This process was repeated until all critical points within a scenario had been covered.

Figure 3. Illustration. Focus group video discussion method.

The second time, the video was shown without interruptions so that participants could get a sense of the flow and timing of the entire drive.

The third time followed the same procedure as the first viewing; however, the pauses were used to engage participants in discussions of the questions about their expectations and their understanding of the situation at that point in the drive. When suitable, the moderator probed participants about driving difficulties, violations of their expectations, and potential remedies for these problems.

Materials

The primary experimental materials were videos of a pilot vehicle navigating the selected interchanges. The videos were filmed from the perspective of a person traveling inside the vehicle. The entire video was geared toward a single interchange scenario with one driving objective (i.e., exiting at a left exit, choosing an exit lane at a two-lane exit, navigating closely spaced critical points, etc.). Each video contained two to four critical points depending on the nature of the interchange and the driving maneuver.

Note that because of the quality of the video footage, sight distances for signs were shorter than in the real world. Participants were provided with separate pictures of the key information sources during the critical points (i.e., higher resolution printed images of overhead signs) to ensure that they had all the information they needed to make relevant driving decisions.

An important concern with the production of video footage was the possibility that drivers may be familiar with the interchanges and know immediately how to execute the maneuver without additional information about the interchange. Not only would this undermine the researchers' ability to investigate how interchange signage and other elements affect driver expectations, but it would also introduce an unwanted source of variance across participants and locations. This was particularly a concern for the focus groups in Seattle, WA, which is where the researchers were based and where it was most cost effective to film the scenarios.

To address this problem, interchanges in Portland, OR, were filmed. These interchanges were far enough away that most Seattle, WA, drivers were unfamiliar with them. Researchers also tried to screen out Seattle, WA, participants who had spent significant time driving in Portland, OR, or who had lived there in the past.

Selection of Interchanges

Three interchanges were selected from those available in the greater Portland, OR, area. The criteria for selecting them was somewhat opportunistic based on which complex interchanges were available in the area and filming constraints (e.g., lighting). Candidate scenarios were evaluated based the types of complexity elements that occurred during each scenario drive. The complexity elements were comprised of those from Chrysler et al. and from those found in the task 2 literature review of this project (see table 5).⁽³³⁾ An overview of each of the three selected scenarios is provided in the following section.

Interchange 1: Visually Challenging Option Lanes

Drivers start on the bridge portion of I-405S/US-30W with the intention of following US-30W. Drivers begin in the left middle lane and must change into the right middle lane to exit using the option lane. After exiting, they encounter another option lane that services the Vaughn Street exit and US-30W. Drivers stay to the left of the gore point to continue on US-30W (not shown in the video). This scenario highlights option lanes, sightlines limited by roadway geometry, and misaligned arrow-per-lane symbols.

Interchange 2: Four-Lane Split with Complex Advance Guide Signs

Drivers start by driving straight on US-30W with the intention of following the signs to City Center. They are in the middle lane when they encounter the first sign for the upcoming roadway split. The first advance guide sign shows City Center as a destination, and the rest do not. When they reach the split, their lane becomes an option lane, and they follow the left leg to City Center. This scenario highlights inconsistent advance signage, limited visibility of signage due to obstructions, and multiple destinations in a close area.

Interchange 3: Poorly Signed Left Exit with Multiple Lane Changes

Drivers start by merging with US-30E onto the I-405N/US-30E bridge with the intention of taking the I-5S exit at the end of the bridge (they have not yet encountered guide sign information about this maneuver). They begin in the right middle lane. Because drivers do not know where the exit is, a potential course would be to choose a suitable lane based on prior expectations. The guide signs appear shortly before the exit, and drivers must make two rapid left lane changes into the option lane to exit onto I-5S/US-30E. This scenario highlights inadequate advance guide signs, an exit in the opposite direction of driver expectations, and lane changes under time pressure.

Table 5 shows the identified complexity factors for each scenario.

Table 5. Complexity factors identified for each scenario.

X indicates "contains factor."

Focus Group Topics

A primary objective of the focus groups was to obtain information from drivers about their expectations at interchanges and about the problems they encounter when navigating complex interchanges. This included identifying the sources of expectation-related problems and the types of remedies that drivers may employ to deal with these problems. However, the specific set of topics addressed depended on the available driving scenarios. Based on this set, it was possible to cover the following topics (additional information about these topics is provided in the Moderator's guide in appendix B):

• Guide signage (arrow-per-lane and diagrammatic signs).
• Guide sign consistency and placement.
• Option lanes.
• Lane selection.
• Maneuver direction (e.g., left-side exits).
• Multiple lane changes.
• Geometric limitations (visual perspective, low sight distance, etc.).

Focus Group Questions

The primary data collected in the focus groups were comprised of the individual participant responses to questions and group discussion summaries that occurred at the critical points in each scenario. These critical points were selected to correspond with times or locations in which drivers needed to make key decisions, where they may have had difficulty, or where their expectations were of particular interest. The questions included both specific references to ongoing elements at those points and general questions about the problems that drivers could be experiencing with the interchange. The final list of questions is included in the moderator's guide (see appendix B).

The focus group sessions also included a warm-up activity in which the groups discussed common characteristics of simple interchanges based on participant responses. This activity accomplished an important objective in that it gave participants the correct frame-of-reference to provide the desired level of detail for their comments during the focus groups. It also got participants thinking about their baseline expectations at interchanges without explicitly telling them what the researchers were looking for. Specific instructions to prime participants are potentially counterproductive when collecting expectation information because they unduly influence the issues that drivers focus on when providing their responses.

Session Timelines

The overall session length was expected to be 90 min with a break about halfway through. The following list provides a general overview of the timeline for the sessions:

• Introduction (10 min): Moderator and participant introductions were conducted, along with disclosures and an explanation of plans and expectations for the next 1.5 h.
• Warm-up exercises (10 min): The moderator directed the participants to discuss characteristics of simple interchanges to put them in the appropriate frame-of-mind.
• Interchange scenario discussions (55 min): Dynamic scenario exercises were used to gain participants' input about the problems in the interchange scenarios and the remedies they suggest to deal with these problems.
• Break (5 min): A break was provided where participants were invited to use the restroom, grab a snack, and stretch their legs.
• Closing (5 min): The moderator provided the group members with an opportunity to share information about any topic that they may have previously omitted.
• Questionnaires (5 min): Participants were asked to complete a brief questionnaire containing questions about their demographics, overall driving experience, interchange driving experience, and familiarity with the specific interchanges discussed.

Data Analysis Plan and Objectives

The raw data in the analysis were the words, phrases, sentences, and non-verbal responses of the focus group participants. The analysis followed a similar approach to one that has been used in other focus group research for the Federal Highway Administration.⁽³⁵⁾ Focus group sessions were attended by the moderator and another researcher who primarily acted as an observer/note taker and helped with focus group materials. Both these personnel were responsible for the analysis, and they examined all data (video recordings, notes, and post-session summaries) for patterns emerging from participant discussions. To analyze and summarize the focus group discussions, both the moderator and observer performed the following tasks:

• Took notes during each of the focus group sessions.
• Developed a summary of each focus group session organized around the key questions/issues addressed during the session. This involved recording individual participant comments that pertained to topics of interest.
• Met to review the summary, compare impressions, discuss differences/discrepancies, and share comments about group interaction, peer pressure, respondent competition, contaminating influences, and subject sensitivity.
• Contributed interpretations and inferences and pointed out any possible biases and contradictions.
• Reviewed video recordings of the focus groups.
• Compiled key findings in a top-line results summary.
• Performed a content analysis on the relevant participant comments.

The basic demographic and driving history questionnaire data were entered into a Microsoft Excel^® spreadsheet, and any discrepancies were resolved by visual inspection to ensure data entry accuracy. Descriptive statistics were calculated for these and any written or survey responses that required a quantitative or categorical answer.

Task 4 Results

The results for the warm-up activity and the primary focus group discussions are presented in the following sections.

Warm-Up Activity Results

Before beginning the dynamic scenarios, drivers were asked some general questions about their expectations at freeway interchanges during a warm-up activity. They were asked to think about what they would expect at a simple interchange traveling from a three-lane freeway onto a major local road. Figure 4 shows a photo shown to participants during the warm-up. The moderator then walked through a set of questions in each focus group session, and participants provided their responses.

Figure 4. Photo. Interchange shown during the warm-up activity.

For each focus group, researchers kept record of whether or not the group mentioned a particular response. If a response was given by at least one individual in a group, the group was included in the count for that response option. The responses given by the majority of the groups (at least seven different groups) are shown in table 6. This table represents driver baseline expectations for simple, easy-to-navigate interchanges, and it serves as a comparison for driver expectations for the more complex interchanges discussed in the main part of the focus group sessions. The complete set of responses is shown in appendix C.

Table 6. Summary of the most common responses given during the warm-up activity.

Focus Group Discussion Results

The results of the focus group discussions are presented in the following sections, which are organized by scenario. Each scenario begins with a description of the roadway, including an aerial view of the interchange showing the driving route and key interchange features/challenges encountered along the way. The scenario driving objectives are also described. These are followed by an overview diagram of the scenario (see figure 5 for a description of the elements in the diagram) and an image of the driving scene at each critical point with an accompanying list of discussion points. The discussion topics for each critical point were based on the interchange complexity factors listed in table 5, in addition to other aspects of the critical point that might influence driver expectations (driver expectancy factors). This information was included in the scenario summaries because it represents some of the elements of interchange driving that were focal points of the discussions.

Figure 5. Illustration. Description of information elements in scenario overview diagrams.

Following the scenario overview information, each critical point is discussed in sequential order. This discussion begins with a brief description of the critical point and an image of the scenario driving scene, which shows some of the key information that participants refer to in their discussions (this image is a larger version of the one shown in figure 5). Also included in this section are the results of the response booklet questions.

The primary results of the focus group discussion are presented after the critical point driving scene images. These are comprised of brief descriptions of key themes and opinions/ideas discussed at each critical point. Because each critical point represents a unique set of driving circumstances, the discussions covered different types of topics, although there were recurring elements across critical points. In order to facilitate reading of the discussion points, they were presented using a similar structure in each critical point discussion. The high-level discussion categories included the following:

• Sign interpretation: This section included an enlarged image of the signs that were shown at the critical point. The discussion included ways in which drivers understood various sign elements such as arrows, exit plaques, and destination information.
• Expectations and strategies: This section provided a discussion of drivers' expectations at that critical point. Driver strategies for coping with the information provided and the decision that they have to make are also highlighted.
• Challenges: This section related to the specific challenges and issues that may have given drivers problems or made them uncomfortable at the critical point.
• Improvements: This section featured driver-suggested improvements for the signs, markings, and geometry at the critical point.
• Driver actions: This section included information about what drivers would do if they were faced with certain information at a particular critical point.

Note that depending on the nature of the discussions, not all of these categories were covered for each critical point. Within each category, key themes and opinions/ideas were summarized. These were typically followed by one to three quotes that were representative of similar comments made by participants. One objective of the example quotes was to capture some of the nuances of the associated comments. These summaries also provided a general sense of the frequency with which a theme or opinion occurred or the level of agreement among participants. In particular, each summary statement included a reference to a magnitude level. The magnitude terms used were based on the following scale:

One < Few < Some < Several < Many < Most < Almost All

The quotes are provided without attribution to individual drivers (to protect privacy), and the demographic category of the speaker (age, gender, and location) were also omitted. During the analysis, it became clear that there were almost no consistent response patterns based on driver demographics. A likely explanation for this is that all demographic groups were represented in most focus group sessions. Consequently, to simplify the presentation of quotes, this information was excluded. Also, some quotes were edited for readability, and missing words were added (denoted by square brackets). Care was taken to preserve the intended meaning of the comments.

Scenario 1

Roadway Description

The roadway in scenario 1, which was located in Portland, OR, was primarily the upper deck of a bridge that exited to a freeway. The bridge deck had four lanes, all moving in the same direction. The sight distance on the bridge was limited by crest vertical curvature. Figure 6 shows an aerial view of the roadway.

Original image: ©2011 Google^®; map annotations
provded by Battelle (see "Acknowledgements")
Figure 6. Photo. Aerial view of scenario 1 roadway.⁽³⁶⁾

The extent of the video footage is shown as a solid yellow line, and the remainder of the intended route is shown as a dashed line.

Driving Objectives

Drivers were told that their objective was to get onto Route 30 West. Figure 7 shows the signs that drivers encountered and the maneuvers that they had to make during the scenario drive. The relative locations of critical points are also highlighted.

Figure 7. Illustration. Sign information and required vehicle maneuvers in scenario 1.

Scenario 1 Critical Point 1

At the first critical point, drivers were faced with two overhead guide signs with arrow-per-lane directions (see figure 8). Because of the crest vertical curve, drivers did not have a view of the roadway geometry ahead.

Figure 8. Photo. Image presented to drivers for discussion in scenario 1 critical point 1.

Key topics for this critical point in the group discussion included the following:

• How drivers interpreted the arrow-per-lane sign.
• What drivers expected the exit ahead to look like based on the sign information.

Response Booklet Question

Since drivers' sight distance was limited by the crest vertical curve in the bridge, they were asked to respond with which of the roadway geometries in figure 9  through figure 13 they expected based on the sign information available in the driving scene image.

Figure 9. Illustration. Response option for scenario 1 critical point 1-two-lane split.

Figure 10. Illustration. Response option for scenario 1 critical point 1-single exit.

Figure 11. Illustration. Response option for scenario 1 critical point 1-two exits.

Figure 12. Illustration. Response option for scenario 1 critical point 1-two-lane exit.

Figure 13. Illustration. Response option for scenario 1 critical point 1-split with option lane.

The distribution of responses is shown in figure 14. The 107 responses are graphed based on the percentage of drivers within each age group who provided that response. Six drivers chose multiple lane combinations and were not included in the graph. In general, drivers expected to see one or two upcoming exits. These expectations were likely influenced by the exit only information above the rightmost lane since both frequent responses represent two versions of that lane exiting with either the right inside lane exiting immediately after (two-exit option) or at some time in the future (single-exit option). Older drivers were less likely to expect a split, and no older drivers chose the actual roadway geometry (split with an option lane).

Figure 14. Graph. Booklet response distribution for scenario 1 critical point 1 (number of responses (N) = 101).

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following sections.

Interpretation of Sign Elements:

The sign in the first critical point was a set of two arrow-per-lane guide signs (see figure 15). The St. Helens destination was positioned over the exit only plaque.

Figure 15. Photo. Guide signs associated with scenario 1 critical point 1.

Arrow-Per-Lane Signs:

When asked, almost all of the drivers said that the arrows referred to specific lanes. Furthermore, each arrow corresponded to a specific destination. Driver responses include the following:

• "[The arrows point to] the lane you should be in to go to the area that's being indicated."
• "Whatever is below this arrow is the lane you want to be in for whatever's above it."

Destination Information-Exit 3 and 30 West:

On the right-hand guide sign, both the sign for Exit 3 and the notation for 30 West were centered above the two downward-pointing arrows. Exit 3 was listed on a smaller, separate sign. Several drivers noticed the split between the two large guide signs and interpreted the Exit 3 sign to apply to both of the lanes on the right-hand sign. For the most part, drivers correctly interpreted this information. Driver responses include the following:

• "Exit 3 is just for the sign on the right because the signs don't connect."
• "Exit 3 is [the two right] lanes."

One driver was uncomfortable with the association of Exit 3 with two destinations. This may have been because the driver felt that those destinations would be served by different exits. The driver indicated that, "I believe that for Exit 3, the exit sign should be over either St. Helens or NW Indy."

The "30 West" label was centered over the two destinations/arrows, so some drivers thought that 30 West could be reached from both of the two right lanes. They indicated that, "That is a little bit confusing, but I'm thinking that 30 West is definitely available to both right-hand lanes at this point."

Some drivers continued this thought by indicating that the right-hand lanes were for two destinations, both on 30 West. Driver responses include the following:

• "If you want 30 West, regardless of what it says, you stay in the right two lanes and then it will get more specific the farther you go, like more instructions. If you want St. Helens, you don't have to stay to the right, I don't think that's true."
• "[Exit 3] is the name of the entire exit, and it just shows different areas that you can go to from that interchange."
• "If I saw that, I'd realize that 30 West is one thing, but there's a commercial route and a bypass."

A few drivers thought that 30 West only referred to the right-middle lane. One such driver indicated that, "I wouldn't know where St. Helens is, if it's east or west. So, I would be staying in the third lane. I know I'm on 30 West and the 30 is over the NW Industrial Area, and it's not really over St. Helens."

Exit Only:

It was less clear to drivers how the exit only indication corresponded to destination information. A few drivers provided varying opinions as follows:

• "That's Exit Only for 30 West, that's what my impression would be."
• "Since the Exit Only is only under St. Helens, I assumed that it only applies to St. Helens."
• "I take it as, the right lane [St. Helens Exit Only] is guaranteed to get off of the freeway you're on right now. If you're under the arrow just to the left of that, you can get off on 30 West or continue where you're going."

Driver Expectations and Strategies:

The first critical point was located immediately before the crest on the bridge, which blocked the drivers' view of the upcoming geometry. There was no consensus about what the exit configuration would look like, and drivers described a variety of different configurations that they expected. There was also no real sense of concern because they expected to receive clarifying information closer to the exit.

Some drivers expected to see a split. Driver responses include the following:

• "[I would expect to see] a split, just because of the four individual lanes."
• "I thought it would be a fork eventually because you can go west in the right two lanes, but then it's saying South, like I-405, so it's going to have to turn somewhere."
• "The arrows tell you [everything]-they say it all. If it wasn't going to split, you wouldn't have that many arrows there."
• "I thought since I-405 is a major freeway, I expected that the split to the right would be smaller. But it turns out that they were equal."

Some drivers expected to see a dual or a two-part exit, and their responses were as follows:

• "I thought there were going to be two exit ramps here-the first one on the far right with an Exit Only and then the next one was dual direction."
• "I would expect the left three to go straight through and there would be a veer off of the right two lanes. So you would have three going straight through, two exiting, and then the far right for St. Helens might have a further veer-off in the middle of the ramp."

Most drivers expected some sort of exit, although a few drivers expressed confusion over whether it was a one- or two-lane exit. Driver responses include the following:

• "There would be an exit on the right."
• "One lane exiting right away."
• "I would expect two lanes to [exit] because "Exit 3" is over both of the two right lanes, the two right arrows."
• "I would expect the Exit Only for St. Helens to be immediate and the Exit 3 for 30 West to be later."
• "I couldn't tell, from this sign at least, if the St. Helens and the NW Industrial Area would exit together, or if there would be a separate exit for St. Helens and another one for the Industrial Area since that was an Exit Only."

A few drivers expected to receive more signs describing what would happen with the exits. Driver responses include the following:

• "[I would expect to see] more signs."
• "As a driver, I don't feel comfortable. I don't feel like, "Oh, I know where I'm going for sure." But, I'm not super worried because I think I'll get more signage."

A few drivers expected the roadway to roughly continue straight on the other side of the bridge as follows:

• "Just look at the sign, the road doesn't necessarily have to split-it could just keep going straight. It could, and then just have the St. Helens exit go off."
• "It's difficult to tell because at this point, all of the arrows indicate that you'd be going straight because there aren't any indications that you would be making a left or right turn at any particular time. My impression was that the two on the left were going to go straight and the two on the right would veer off, but there's nothing really that would indicate it based on that sign."
• "[I would expect to see] four lanes [on the other side of this bridge]."

Challenges:

At the first critical point, drivers were mainly challenged by reading the signs. The volume of text presented as well as the lack of definition between the left and right sign panels were mentioned as challenges by some drivers as follows:

• "The sign above the one on the right that says Exit 3, I didn't even catch that until we stopped to look at it for 5 minutes. There's so much text up there already."
• "I would like to see a little more definition of the difference. It's kind of broken there [into two signs], and when you're going through there at 60, 70 miles per hour you may not even see that."

Only one driver commented about arrow-per-lane signs in general and how the arrows visually line up with lanes at this point. The driver indicated that, "This is pretty straightforward with the arrows, but sometimes in general, when I see the arrows, [I can't figure out which lane they point to]."

Improvements:

Drivers also had a number of suggestions for sign improvements. For several drivers, the first area for improvement focused on the grouping of destination information on the signs as follows:

• "Is that a hyphen? Do you go to NW Indy Area and St. Helens on 30 West [to the right] or is it NW Indy Area [in the right middle lane] and St. Helens [in the far right lane]. Similarly with the sign on the left, I don't know what the hyphen means. It looks exactly like it's just one street or one area categorized."
• "I think it should say NW Industrial Area AND 30 West left lane because you have to look at the Exit Only sign too and you know you're going to get to St. Helens on that Exit Only."
• "I thought 30 was for the whole thing and I realize now it isn't. So, they should say "local" or put some other little thing up there to tell you it's just a surface street or split the sign in two maybe because I thought you could get on 30 from both of [the two right lanes] or they were for two directions on 30."

For several drivers, the second area for improvement was the addition of distance information to the sign. Driver responses include the following:

• "I think you should have some advance notice like "quarter mile ahead" or "exit half mile" because you've got limited sight distance coming over the crest of the bridge and if there's heavy traffic or it's foggy, you don't necessarily know how far the exit is going to be."
• "Then again, on the right side, the 30 West sign, it doesn't say when it is, so it may continue for a while and then branch off."

A few drivers found that they were able to deduce some distance information from the fact that they were on the top of a bridge. One driver indicated that, "I don't know that I would anticipate a split by looking at that and being on the top of a bridge. First of all, I'm on a bridge, how many things can they do on the top of a bridge. I don't know that I would be anticipating that these would split into different directions as a result of that signage."

Scenario 1 Critical Point 2

At the second critical point, drivers saw the same signs that they did at the first critical point (see figure 16). The main difference is that drivers were then faced with a split, and the third lane became an option lane. Additionally, the lane marking between the third and fourth lanes became a solid white line.

Figure 16. Photo. Image presented to drivers for discussion in scenario 1 critical point 2.

Key topics in the group discussion for this critical point included the following:

• Which lane drivers would choose to follow 30 West.
• Drivers' opinions about option lanes.

Response Booklet Question

At the second critical point, drivers were faced with a lane decision for 30 West. Figure 17 shows the lane options as presented in the response booklet. Lanes 3 and 4 were two legs of the same option lane. The 30 West destination was listed on a sign above lanes 4 and 5.

Figure 17. Illustration. Lane numbers for lane choice decisions in scenario 1 critical point 2.

As shown in figure 18, the majority of drivers chose lane 4 to get to 30 West. Interestingly, older drivers were the most likely to choose lane 5, which was labeled as an exit only lane and was separated from lane 4 by a solid white line.

Figure 18. Graph. Booklet response distribution for scenario 1 critical point 2 (N = 109).

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Interpretation of Sign Elements:

The signs that drivers discussed in the second critical point were the same as in the first critical point (see figure 19). The context was different, however, since drivers could clearly see the freeway split at this time. Note that because the sign was the same, driver interpretation of the sign elements is not covered in this critical point.

Figure 19. Photo. Guide signs associated with scenario 1 critical point 2.

Driver Expectations and Strategies:

At the second critical point, drivers were asked to make a lane choice decision for 30 West. Several drivers were uncomfortable with associating the 30 West sign element with multiple lanes. They either used other sign elements to make their decision (e.g., the exit only plaque) or tried to deduce which area (i.e., St. Helens or NW Industrial) was serviced by 30 West. Driver responses include the following:

• "How would you know if Highway 30 would lead you to the Industrial Area or to St. Helens? If you get into the inside [inside right lane] where it says NW Industrial, and then around the corner and it says 30 to St. Helens. You have to get over real quick. Hopefully there's enough space in these areas to get where you need to go."
• "If I didn't know the city, I just had to go to 30 West, then I would be very confused at that particular spot, which of those two lanes is 30 West, can I get there both ways."

Lanes 4 or 5:

Many drivers stated that they would choose either lane 4 or lane 5. Some of the decision factors that would help them choose a lane include keeping their options open and knowing which specific destination on 30 West they want. Driver responses include the following:

• "At the last minute, if I'm in that fourth lane, I can make a choice either here (fifth lane) or there (fourth lane) at the last minute, versus being locked into that fifth lane."
• "If I know where I'm going-like the destination is St. Helens-then I would know that I want the [rightmost] lane. But if I didn't know the city, I just had to go to 30 West, then I would be very confused at that particular spot. I don't know which of those two lanes is 30 West. Can I get there both ways?"

Lane 4:

Most drivers chose lane 4 to avoid the exit only lane. Driver responses include the following:

• "And since there's nothing on any of these signs that gives you any inclination as to what the distance is, how do you know that you won't go around that curve and be automatically on an exit ramp. Especially with that solid line down the middle of both lanes, it seems to me to be saying "hey, make up your mind", so that's why I chose 4."
• "Either of the two right lanes will take you to 30 West, but the far right lane is just an exit for St. Helens. So, I'd stay out of the Exit Only lane."
• "Since there're two exits, it says "exit" up top and it says "Exit Only" to the bottom right; that makes me think that there's not only an exit coming up immediately, but a separate exit in addition to this 30 West exit. So that's one of the reasons why I picked to go in lane 4 because I'm thinking that there's going to be an exit immediately going onto a side street and that's not where we wanted to go, we wanted to go to 30 West."

Lane 5:

However, a few drivers were uncomfortable eliminating the exit only lane and chose to be in lane 5, the rightmost lane. Driver responses include the following:

• "I chose lane number 5. I don't know why but the Exit Only sign made me think I have to be in that lane."
• "[I chose lane 5 because] that's where you would be bearing when you're going on the exit."
• "I took the Exit Only because I thought that was 30 West and also [because] somebody might be [splitting left] and I might be [splitting right]. See I didn't know if 30 was going to St. Helens or going to the Industrial Area."

Scenario 1 Critical Point 3

As drivers came around the curve on the exit, they were faced with multiple additional sets of signs. Critical point 3 was placed at the last set of these signs right before an exit (see figure 20). Two sets of signs before this critical point (not shown) indicated to drivers that 30 West and St. Helens were in the left lanes.

Figure 20. Photo. Image presented to drivers for discussion in scenario 1 critical point 3.

Key topics in the group discussion for this critical point included the following:

• The arrows and how well they indicated the lanes.
• Lane destinations.

Response Booklet Question

At the third critical point, drivers were asked whether 30 West continued over the bridge or under the bridge. This was an operationally relevant question since 30 West was their ultimate destination. At this point, the vehicle was in an option lane-the left leg led to 30 West, and the right leg led over an overpass to Vaughn Street. The lane was marked by two arrows, one for each destination. The visual perspective makes the lane direction ambiguous; however, the length of the pause at the critical point and drivers' ability to count lanes to match with destination arrows allowed most drivers to figure out that 30 West was under the bridge. Figure 21 shows the distribution of responses. Two older drivers were unsure and circled both responses. As a result, they are not included in the graph.

Figure 21. Graph. Booklet response distribution for scenario 1 critical point 3 (N = 107).

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Interpretation of Sign Elements:

The signs that drivers discussed in the third critical point were three arrow-per-lane signs (see figure 22). The option lane was indicated by the rightmost arrow on the middle  sign (St. Helens), and the leftmost arrow on the right sign (Vaughn St.). The Nicolai St. sign was the first sign where drivers encountered information about that destination.

Figure 22. Photo. Guide signs associated with scenario 1 critical point 3.

Lane Destinations:

By the time drivers got to this last bank of signs, many were confused by the discontinuity of destination information that had been provided to them. Driver responses include the following:

• "And [now there's] no mention of the Industrial Area, which I guess is Vaughn and Nicolai, who knows. So it should say "Nicolai" and "Vaughn Street" instead of the Industrial Area."
• "The wording is not consistent. What you're telling me is changing constantly. What happened to NW Industrial and Vaughn St came out of nowhere. Just leave it out, you're confusing me. Just say "St. Helens" and keep it that way."

Arrows for the Option Lane:

Several drivers were able to understand that two arrows on separate signs pointed to the same lane, the option lane for St. Helens and Vaughn Street. Driver responses include the following:

• "What lets you know you have an option lane is that the right arrow for St. Helens and the left arrow on Vaughn Street, that's the exact same lane. It marks the same lane so it lets you know that you do have an option."
• "I'm pretty sure the right arrow on the Vaughn Street sign and the left arrow on the St. Helens sign should be pointing to the same lane."

However, some other drivers had difficulty determining this. One stated that, "The fact that the left arrow on the Vaughn Street sign and the right arrow on the St. Helens sign point to the same lane is confusing. You have to deduce it yourself."

The mismatch between the number of arrows (five) and the number of lanes (four) added to the confusion for some drivers. Driver responses include the following:

• "I see five arrows, but I count four lanes even though one might be that option lane."
• "I would never have enough time driving to figure out what I figured out [from the driving scene image]."
• "One of the really confusing things about that is that there are five arrows and there are only four lanes because that Exit Only looks like it's over the [break-down] lane. And then you've got the second sign from the left, the second arrow for Vaughn Street looks like it's in the right-hand lane and then you've got the two for St. Helens. And then you're going to come up to that "Y", and you're going ‘where am I?'"

Driver Expectations and Strategies:

At the third critical point, drivers encountered new destination information, which led to some confusion because the change in the destination set was unexpected.

At the second critical point, the right lane was labeled "Exit Only" and had the destination St. Helens with an arrow. After that point, the drivers rounded the corner of the two-lane exit ramp and saw another sign stating "St. Helens Left Lane," which contradicted the previous signs. At the third critical point, "Vaughn Street" was marked in the right lane and "St. Helens" was marked in the middle two lanes. This discontinuity of lane association with destination information violated some drivers' expectations. Driver responses include the following:

• "Coming around the bridge, the sign to St. Helens was on the far right. I would've been in the right lane if I was going to St. Helens and didn't know the road. But now, as soon as I come out of that exit, I have to get left because I'm in the wrong lane. To me, that's the worst thing about what we've seen so far because St. Helens is an Exit Only on the far right and then they want you to go left once you get out of that bend."
• "St. Helens starts off on an Exit Only and then it ends up on the left side and then there's another Exit Only [to the right]."

This change in lane destination would have upset a few drivers. Driver responses include the following:

• "Now you've got to merge all the way over, that could be a problem. I would be upset when I saw you had to merge left."
• "They told me to get far right, Exit Only; now they're telling me to go far left? I'm irked! As a driver, I'm stressed, because merging is stressful. I know what I'm going to do, I don't know what you're going to do. You're asking me to get three lanes over, not just one."

Challenges:

At critical point 3, the driver's perspective was such that the arrows on the arrow-per-lane signs did not align, and the arrow for the option lane looked like it allowed the driver to take either branch to reach the destination 30 West. Several drivers were unsure about which lane to take. Driver responses include the following:

• "I thought the sign in the middle was kind of confusing too because it looks like if you go straight you'll be on 30 but if you go off to the right you'll also be on 30. I didn't think it was clearly marked."
• "I've been able to figure out how to go to 30 West, but I think that if I was driving it, I would have been just as likely to end up in the right lane of the option lane as going under the bridge."
• "You almost think you could do both-I had to actually count the lanes to figure it out. It absolutely looks like you could follow [the blue SUV] and get to St. Helens."

Many drivers were able to correctly deduce the answer given the pause in the video. Driver responses include the following:

• "The reason I said under the bridge is because when you look at Vaughn, it looks like it's going up, so 30 West has to be going under."
• "Being there, you could more clearly see that the far right area was a shoulder and the one arrow was definitely to Vaughn so you could have a fairly clear indication that 30 [West] was going under the bridge."
• "A reasonable driver will see that two of the lanes are Exit Only, one lane goes over the bridge, and the 30 [West] is the two center lanes going through."

Some drivers noted that this was sometimes a challenge with arrow-per-lane signs. Driver responses include the following:

• "I think it's often the case that when you're pointing to the lanes like that-that from a distance it looks different-they seem to shift over when you get closer. You think it's the middle two lanes and then you get closer and realize it's the left two lanes or something like that. I don't think you can necessarily tell, maybe because the road curves."
• "It all depends on the angle. If you're in that lane, you can properly use the arrows; if you're in another lane, the arrows throw you off."

Improvements:

Several drivers thought that canted or tilted arrows would more clearly convey that the option lane serves both St. Helens and Vaughn Street. This suggestion most frequently came from drivers in the Columbus, OH, focus groups, as they frequently encounter these types of arrows.

One implementation would have diagonal-pointing arrows on the existing option lane sign. Driver responses include the following:

• "A lot of places in Columbus when they do that they have the arrows pointed [downward and toward each other] at an angle. The right arrow on the 30 West sign would point slightly off to the right and down, and the Vaughn Street sign, the left arrow would point slightly to the left and down."
• "I've also seen situations like this where those arrows representing the same lane would be angled pointing toward the same one of four. [I think that would make it clearer.] Or a visual that shows a split coming up."

One driver thought of another implementation, which would have diagonal arrows on an additional sign at the gore point. The driver indicated that, "One of the things that I've seen that helps at interchanges like this is right at the point of that "Y", they'll have a sign that says "30 West" with an arrow pointing to the left and "Vaughn Street" with an arrow pointing to the right. So that as you're coming up, you can look at it and it tells you (gestures split)."

Option Lanes in General

In critical point 2, drivers provided opinions about option lanes in general.

Positive Opinions:

Many drivers liked option lanes, especially in unfamiliar areas, because they provided more margin for error when they were not sure which lane to choose. They also felt that they had more time to make a lane decision. Driver responses include the following:

• "I think it's good because in instances where you're not familiar with the area and say you're three lanes over and you have to merge three lanes say in a quarter of a mile, that's one less lane that you have to merge over, so it makes it safer."
• "I think it lets me make that last-minute decision at the furthest place I can if I'm confused coming up to it, then you can make a decision. Instead of having to get over, you can go either way."
• "I like that they give me enough time so that if I know that an exit is coming up, I can be in there if I'm not quite sure where I'm getting off. I don't like when some are option lanes and some are Exit Only lanes (alternating), it causes unnecessary lane changes and then suddenly you can't get back over."

Negative Opinions:

However, some drivers preferred to avoid option lanes, if possible. One reason for this preference was driver familiarity with the interchange. Driver responses include the following:

• "If I know where I'm going, I'd rather take the Exit Only lane."
• "[If I'm a local] I like the dedicated exit lanes. If I know I'm going to 30 West, I want to be over there in enough time to make that turn."

Another reason that a few drivers gave for staying out of the option lane was to avoid drivers who use the option lane but are not sure where they are going. Driver responses include the following:

• "I think option lanes make me nervous though because that's people's panic lane. If they're right at the end and they don't know where they're going, that's more chances for them to freak out and move to the next lane. So I don't like that sometimes."
• "My only problem with them is if someone is in front of you and wants to exit over to the 30 but hesitates just a little, you're doing 60, you have to be very observant and slow down to let them do that. Some people will go past where the white lines are and then still merge over. Other than that I agree with what he said. I like them, but you just have to be careful."
• "When you're going like that and you're going to make a decision, you have to be much aware of what's behind you because there are going to be cars right up on you while you're trying to make a decision. And too, when someone is behind you, they assume that you know where you're going."

A few drivers mentioned that they would avoid option lanes when there is congestion. Driver responses include the following:

• "In this scenario when there's no traffic, I'm looking at the option lane because if I'm seeing something I don't expect I can always just change my mind in the option lane on days like this, but during rush hour I'd go in the dedicated lane."
• "If I know where I'm going, I prefer one of the other lanes because traffic can sometimes stack up in that option lane. Especially if less traffic is going my way, more traffic is going the other way."
• "The other nice thing about them is if all of a sudden you saw that the option lane was getting really congested [off the exit] and you knew that the next exit along would get you where you wanted to go, you could opt to stay in that lane."

Scenario 1 Key Themes

Some of the key themes expressed in scenario 1 are as follows:

• Drivers do not get a clear picture of an upcoming interchange with an uncommon geometry based solely on arrow-per-lane guide signs. However, this does not necessarily cause problems or stress for drivers since they expect to get more useful or detailed information closer to the interchange.
• Lack of continuity in the set of destinations encountered by drivers makes some drivers uneasy. In particular, drivers may develop expectations about which destinations are possible for their exit/maneuver. When this set of destinations changes unexpectedly (e.g., NW Industrial Area disappearing or Nicolai St. appearing seemingly out of nowhere) without corresponding exits and entrances, it can lead to driver confusion.
• Drivers seem to interpret lane arrows rather narrowly to correspond to information that is directly above or grouped with the arrow. For example, while both NW Industrial Area and St. Helens could be reached by either right-hand lane, because the destinations were each directly above an arrow, drivers instead paired each destination with one of the lanes. There was even an inclination for some drivers to pair the 30 West destination with a lane even though it was in between both arrows. This tendency led to problems later in the scenario because drivers associated the rightmost lane, which was an exit only lane, with St. Helens when the exit was for a different destination (Vaughn St.).
• Option lanes are particularly appreciated and used by drivers who are unfamiliar with an area but are used more strategically at familiar interchanges (e.g., to avoid congestion). However, some drivers still prefer the certainty associated with exit only lanes.
• Lane arrows require extra work from drivers when they are used to denote option lanes. This information is indirect in the sense that drivers have to deduce that the two destinations point to a single lane as well as to other lanes that head off in different directions.
• Drivers like distance information for upcoming exits.

Scenario 2

Roadway Description

The roadway used in scenario 2 was primarily a sunken freeway with a limited view of the surrounding urban area. The freeway was crossed by several overpasses that limited sight distance in curves. Figure 23 shows an aerial view of the roadway.

©2011 Google^®; map annotations provded by Battelle (see "Acknowledgements")
Figure 23. Photo. Aerial view of scenario 2 roadway in Portland, OR.⁽³⁷⁾

The extent of the video footage is shown as a solid yellow line, and the remainder of the intended route is shown as a dashed line.

Driving Objectives

Drivers were told that they were on 30 W driving in from the outskirts of town, and their objective was to get to the Portland City Center. To ensure that drivers did not think they were going to Seattle, WA (a destination that figures prominently on the signs), drivers were reminded that they were in Portland, OR. Figure 24 shows the signs that drivers encountered and the maneuvers that they had to make during the scenario drive. The relative locations of critical points are highlighted.

Figure 24. Illustration. Sign information and required vehicle maneuvers in scenario 2.

Scenario 2 Critical Point 1

At the first critical point, drivers approached a bank of signs mounted to an overpass (see figure 25). The vehicle was already in the correct lane for reaching the target destination.

Figure 25. Photo. Image presented to drivers for discussion in scenario 2 critical point 1.

A key topic for this critical point in the group discussion was the meaning of multiple destinations listed on the same sign.

Response Booklet Question

At the first critical point for the second scenario, drivers were presented with arrow-per-lane signs with multiple destinations on each sign. Drivers were asked to select whether the signs indicated that City Center and Seattle were serviced by the same exit or whether the middle lane allowed them to reach both destinations. Figure 26 shows the distribution of responses. Five drivers either wrote in their own responses or selected both options and were not included in the figure. Most drivers thought that the middle lane would lead them to both destinations but that it did not necessarily indicate an exit.

Figure 26. Graph. Booklet response distribution for scenario 2 critical point 1 (N = 111).

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Sign Interpretation:

The signs that drivers discussed in the first critical point were three destination signs with downward pointing arrows (see figure 27). For the most part, drivers were able to obtain the key information from the signs.

Figure 27. Photo. Guide signs associated with scenario 2 critical point 1.

Multiple Destinations:

Almost all drivers correctly interpreted the meaning of the sign where the two destinations above the arrows could be reached by taking the indicated lane.

Driver responses include the following:

• "You take the same lane to get to both locations."
• "If you follow the signs, you will get to both locations at some point. And then the signs will get more specific as you get closer to your exit."
• "I would know to stay in that lane. I know that there are going to be some changes down the line, but I will be okay if I stay in [the center] lane. That lane will take us to both."

Destination Order:

Some drivers also interpreted the order of the destinations as indicating the relative proximity of each destination. One driver indicated that, "I always read this as the first one [top destination] is the closest location and the last one [bottom destination] is the furthest location…and that the first one is close by but the second one is very far away."

However, there were also some other drivers who did not see the destination order as communicating relative distance. One driver indicated that, "I didn't assign any meaning to the order of the destinations. I'm new to town, looking for City Center, I see it on the sign with the arrows, so I'm going to stay in this lane. I didn't think about order-I'm scanning the signs quickly, watching for traffic around me."

Expectations and Strategies:

A few drivers were confused by the layout of the sign information. In particular, these drivers tried to assign meaning to systematic sign characteristics that they were unfamiliar with-in this case, the placement of the arrows on the right side of two of the signs. One driver commented, "Why are the arrows to the right of the signs? What are they trying to say? I'm not used to this, and it makes me wonder if it has a specific meaning."

Challenges:

A few drivers reported confusion or problems distinguishing the multiple destinations on the signs. This is certainly a potential problem with drivers who are unfamiliar with an area; however, it may have also arisen because the scenarios lacked sufficient contextual cues to clearly differentiate City Center from Seattle (i.e., no drivers from the Seattle groups had this problem since it was obvious to them that the scenario was not in Seattle). Driver responses include the following:

• "I'm used to seeing "City Center" paired with the name of the city. So I wanted to read that as "Seattle City Center" not Portland."
• "The way the sign is written, it looks like there is only one destination. There's no slash or divider separating the destinations. If you are coming from out of town, you might not know that those are two separate destinations."
• "I'm trying to get to Portland City Center. I don't understand why Seattle is even on this sign. It's just confusing to me. There is no definition between the two. Same font, same color, you assume it's the same grouping-it just looks like a single destination."

Scenario 2 Critical Point 2

Shortly after passing the signs in critical point 1, drivers reached the next sign (see figure 28). Drivers did not need to change lanes at this point.

Figure 28. Photo. Image presented to drivers for discussion in scenario 2 critical point 2.

Key topics in the group discussion for this critical point included the following:

• What information diagrammatic signs provide about upcoming interchanges.
• Drivers' opinions about the information this sign provides regarding the City Center destination.

Response Booklet Question

At the second critical point, the objective destination, City Center, was not included on the sign. Drivers were asked whether they would go north or south on Interstate 5 to reach City Center. Figure 29 shows the distribution of responses. Four drivers either stated "neither south nor north" or that they did not know. Almost all of the drivers said that they would go north to reach City Center. The listed destination for the northbound direction, Seattle, was paired with City Center on a previous sign at critical point 1.

Figure 29. Graph. Booklet response distribution for scenario 2 critical point 2 (N = 105).

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Sign Interpretation:

The diagrammatic sign indicated that the freeway will eventually split into two directions. It will also go from three lanes to two lanes in each of the north and south directions (see figure 30). The center lane is shown as an option lane that goes in both directions. Only two of the original destinations are shown on this sign.

Figure 30. Photo. Guide sign associated with scenario 2 critical point 2.

Route Guidance Information:

Several drivers reported using the diagrammatic sign primarily for obtaining a high-level view of what happens at the interchange and where they need to go, but they did not particularly focus on the more detailed sign elements. Driver responses include the following:

• "I typically don't take them absolutely literally, just as a general idea of what will happen."
• "I just follow the arrow and look for the [destination] that was closest to the one that I was going to."
• "I'm not going to register the dotted lines that quickly. I can see them, but all I'm going to register is the splitting arrows, and the words, and maybe the I-5 [symbol]."
• "It happens too fast for me to even notice the lane dots. I'm looking at the fact that it splits and there's Seattle and Salem, and that's all."

It was also clear to several drivers that the sign indicated that there was no option to go straight. Driver responses include the following:

• "It's going to force you to make a decision. You can only go one way or the other way."
• "You can't go straight."

Information About Lanes:

Although some of the quotes listed in the previous subsection indicate that some drivers ignored the lane information provided in diagrammatic signs, many drivers used this sign element to obtain a more literal interpretation of how the lanes will transition at the interchange. Driver responses include the following:

• "My impression is that the middle lane is the option lane. You start with three lanes and then it will split to four lanes."
• "I do take literally that if you are in the center lane, you will have to make a decision at some point."
• "It relates to what you have right now, and relates to what you will encounter in the future."

Misinterpretation of Diagrammatic Sign Information:

Some drivers also indicated that they had difficulty determining what happens to the middle lane, or they incorrectly assumed that this lane would continue through the split. Driver responses include the following:

• "Under normal circumstances, I'm very visual and I like pictures like this a lot and process them faster, but I get very confused because I couldn't figure out what happens to the middle lane. There are only two arrows."
• "I misread the number of lanes before the split. It only looked like two lanes to me, so this sign was more confusing than anything. I couldn't figure out what the middle lane that I'm in now was going to do."
• "What that is telling me is that you are approaching a major interchange where you are going to have a choice of going north or south. If you don't want either of those, than just stay in the middle lane and go through."

Expectations and Strategies:

The presentation of this diagrammatic sign after the destination sign (critical point 1) caused problems related to driver expectations for drivers because the diagrammatic sign did not provide additional information about their specific destination (City Center).

Some drivers reported becoming uncomfortable when they did not get the information they expected (i.e., where to go for City Center). Driver responses include the following:

• "The sign tells you there are three lanes and two directions, but it doesn't tell you which way to go."
• "I'm forced to guess. And I shouldn't be."
• "At this point, I would be freaking out. Where did City Center go?"

The key outcome of the missing information about City Center was that most drivers incorrectly assumed that the grouped destinations (City Center and Seattle) shared the same direction, not just the same lane³. Driver responses include the following:

• "Because of the way that Seattle and City Center are linked on the sign, I thinking that they are going to be linked on the road."
• "Because the last sign said Seattle and City Center, I would be thinking that I need to go right here [towards Seattle]."
• "My inclination after seeing this sign would be to get into the right lane, because I think Seattle and City Center go together. This would make it very difficult for me to take the [correct] exit later on because I'd be in the wrong lane."
• "I'd probably get into the right lane, since I think I have to go right to Seattle to get to City Center."

A few drivers openly recognized that they were being required to imply or guess the direction of City Center based the association between City Center and Seattle on the previous sign. This caused drivers annoyance that they had to make this assumption. Driver responses include the following:

• "A problem I have with this type of sign is that you have to keep track of two destinations in case your destination doesn't show up on all the signs"
• "When I saw this I had to stop and think: okay Seattle and City Center were joined on the other sign so I better follow Seattle. If you are driving, you don't want to have to take that extra step in thinking, especially if you are not familiar with the area."

A few drivers alluded to the concept of route continuity (i.e., the center lane to continue). In absence of other information, these drivers expected to continue on the main route and not exit. Driver responses include the following:

• "Experienced drivers expect the center lane to go through. Having a sign that tells you it is a through lane is even better."
• "If you stay in the middle, you stay on 30W."
• "I thought that I had to stay on US-30 to get to City Center since we didn't see any more signs about it. Just before this, we saw a sign that said US-30 next right, so I would have been in the right lane. At this point, I would have not had enough time to change into the [correct] lane."

Challenges:

One specific challenge identified by a few drivers is that they found the switch between the arrow-per-lane and diagrammatic signs to be a source of concern. Driver responses include the following:

• "This sign is not consistent with what we've seen up to this point. We went from a sign that is talking about lanes to one that is talking about direction."
• "There should be better consistency in the signs. I don't like having different types of signs in that short of a distance. It is confusing."

Improvements:

Drivers mentioned a few ways in which signage could have been improved to make it easier for them to navigate the interchange. A few drivers mentioned that distance information would have been useful for estimating how much time they had to prepare for the interchange split. Driver responses include the following:

• "I like exit distance information on signs. I don't like signs that don't have them because you don't know when the next sign is coming."
• "Neither of these sets of signs says how far until the split happens. If they signs did [provide distance information] it would give me a chance to prepare for the split."

Also, several drivers had suggestions for addressing the primary navigation challenge, which was the lack of information telling them which direction to go for City Center. Driver responses include the following:

• "How hard would it have been to [put] City Center above Salem. Then there would not have been any question."
• "Wouldn't this sign be easy to fix? You just need to add in City Center and Convention Center/[Rose Quarter]. It's not like there is a lack of space for it."

Driver Actions:

With regard to specific driver actions, a few drivers reported that if they do not understand a sign or if they have uncertainty about the sign information, a safe strategy seemed to be to stay in the middle lane. Driver responses include the following:

• "This sign did not really tell me what to do. I would stay in the center lane, but I couldn't figure that out from the sign."
• "I would try to stay in the middle lane as long as possible until I got more specific instructions about where to go. Because based on this sign, I have no idea where to go."
• "This sign threw me because-based on the previous sign-I was expecting the highway to continue straight, and the exit for City Center to be an exit. I wasn't expecting an actual highway split like this. And when it said Seattle to the right, now I'm not sure where to go. Last thing I saw about City Center was to stay in the middle lane. I'll do that, but I'm totally confused."

Scenario 2 Critical Point 3

The third critical point was near an overpass that held two signs that provided similar information as the sign at the previous critical point (see figure 31). The roadway at this point begins curving to the right and upwards, and sight distance is limited by the overpass directly ahead and another one just beyond that one.

Figure 31. Photo. Image presented to drivers for discussion in scenario 2 critical point 3.

Key topics in the group discussion for this critical point included the following:

• What information the arrows communicated about the upcoming roadway geometry.
• The relationship between the arrows and the individual lanes.

Response Booklet Question

No response booklet question was asked for this critical point due to time constraints.

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Sign Interpretation:

The signs at this critical point contained much of the same information as the diagrammatic sign in the previous critical point but without the lane information (see figure 32). The direction information was presented on separate signs, and this may have led to driver confusion about how to interpret the relationship between the directional arrows and the lanes on the road.

Figure 32. Photo. Guide signs associated with scenario 2 critical point 3.

Split Information:

For the most part, the information about the freeway split was adequately communicated by the signs. Several drivers viewed these signs as providing directional information, specifically indicating a north/south or a left/right split. Driver responses include the following:

• "I interpret these arrows as showing a major split in I-5, something is changing drastically. It's just not a small turn in the road."
• "I see the arrows as directional because typically, if the arrows pertain to lanes, they point down towards the lanes."
• "My impression from the previous sign and this one is that all of the lanes are split and your options are north or south. I wouldn't assume that the center lane would go anywhere other than north or south."
• "That's also telling me that I'm approaching I-5 and that I have a chance to go north or south."

Arrow Position:

Several drivers also tried to link arrows to specific lanes on the road even though this sometimes resulted in incorrect conclusions about what the lanes did. Driver responses include the following:

• "These signs are kind of weird. There are three lanes here but only two arrows. So I couldn't figure out which lane went with which arrow."
• "I see the arrows as showing what the outside lanes do, but I cannot figure out what the center lane does from this sign."
• "I'm assuming the two lanes on the right are going to go to Seattle, and the one lane on the left goes to Salem."

There were also a few drivers who mapped the arrows to their spatial impression of the roadway geometry. Driver responses include the following:

• "Another thing that is confusing is that the road goes to the right, and there's an arrow that goes to the right. But there is also an arrow that goes to the left, but no road that goes to the left."
• "If you look at the road, the left lanes look like they go straight. I was expecting it to curve off more. It does not look like the sign at all. This is a little confusing to me."

Timing of Split:

For a few drivers, seeing the "split arrows" repeatedly implied the imminence of the split.

• "I would expect the split to be close, since those are the only signs that I'm seeing now."

Lane Markings:

The exit lane markings caused confusion for at least one driver. It was not clear which part of the split contained the actual exit.

• "I know that the [exit lane markings] on the right represent an exit. I'm asking myself, what the center lane is for. I'm expecting the left lane to cut out South and the right lane to take me North. So I'm really concerned about what am I still doing in the center lane."

Expectations and Strategies:

Several drivers expressed frustration about not getting the information they needed about City Center. However, based on their responses to the first sign in the scenario, most seemed to understand that the center lane would take them to City Center. This suggests that drivers became concerned if they drove extended stretches without seeing expected information. Driver responses include the following:

• "After I see this sign after the last one, this is where I start to get worried. I haven't seen anything about City Center in a while."
• "If I was going to City Center, I'd be totally confused at this point. City Center just disappeared."
• "I don't know what's coming up."
• "I would be much more comfortable up there with three signs for the three lanes. I don't have much time to figure this out when I have to watch for traffic and so forth. I really want them to tell me what will happen so I can just worry about being in the correct lane without having to figure out where I'm going."

Scenario 2 Critical Point 4

In critical point 4, drivers encountered a bank of guide signs immediately after traversing a combination horizontal/sag-vertical curve that passed under an overpass (see figure 33). This created a blind curve that limited sight distance and the amount of time that drivers had to view the sign information. Another potential challenge to drivers was the gore point immediately ahead of them. Because the gore point occurred following a horizontal curve, drivers needed to continue steering to the left to avoid it (if they were headed to City Center).

Figure 33. Photo. Image presented to drivers for discussion in scenario 2 critical point 4.

Key topics in the group discussion for this critical point included the following:

• What information surprised drivers.
• Strategies for sign reading given the large amount of information presented.

Response Booklet Question

At the final critical point in scenario 2, drivers were asked five questions that all focused on whether the approach signage adequately prepared them for various dimensions of the freeway lane split. The response distribution is shown in figure 34.

Generally, drivers felt unprepared for most aspects of the split. Many of the drivers knew that a split was coming; however, few knew which lane to be in or which direction to go. One surprising result was that except for younger drivers, the majority of drivers in other age groups did not expect that they could go in both directions from the center lane despite previous signage indicating that they could. Younger drivers were also the most prepared for the split.

Figure 34. Graph. Booklet response distribution for scenario 2 critical point 4 (N = 109 to 111).

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Sign Interpretation:

The signs in critical point 4 were comprised of one guide sign for each lane, including a down arrow (see figure 35). The key sign for the scenario navigation task was the left-middle sign (City Center). Also included on that sign was destination information for a local tourist attraction (the Oregon Museum of Science and Industry (OMSI)). Drivers saw another sign for this attraction earlier during the approach.

Figure 35. Photo. Guide signs associated with scenario 2 critical point 4.

Sign Information:

Some drivers reported that they liked the sign information but thought that the information would have been more useful if it had been provided earlier. Driver responses include the following:

• "The sign itself is pretty good. But it comes too late."
• "Why couldn't they have shown this earlier?"
• "I think the sign comes too late. You don't see it until you are very close to where you have to make a decision, because of the overpass [blind curve]. But if you put that sign on the overpass itself, it might confuse people more [since they can't see all four lanes]. But you have to find some way to give drivers more preparation."

Sign Reading:

Some drivers reported that when faced with the time-limited viewing conditions represented by the current critical point, their primary method of obtaining sign information would be to scan for key information. Driver responses include the following:

• "I would look for the sign with City Center on it. Everything else I would ignore."
• "I would be in panic mode at this point, so I would be scanning quickly for the City Center sign."
• "I think somehow we pick out what we are looking for amongst all the other stuff. We see instantly, there it is."

However, a few drivers reported that they would read from left to right. One stated, "I read these from left to right as fast as I can, and I stop reading as soon as I see what I want. Because you don't have time to read all that and make your lane change."

Expectations and Strategies:

A key challenge in the current scenario is that immediately prior to seeing the signs at this point, most drivers were prepared to follow signs for Seattle to get to City Center. This incorrect expectation was likely formed based on the destination signs at the start of the scenario and compounded by the fact that drivers received no other information about City Center until this last set of signs. Driver responses include the following:

• "All the signs I've seen before this said Seattle right or 30W right. There was nothing to prepare me to separate City Center from either 30W or Seattle."
• "We were sold a couple of signs back that if we stayed in the lane for Seattle, we were going to go to City Center. So I'm prepared to go in one direction, but, what the heck? Now I have to go in the other direction."
• "My assumption from City Center being labeled with Seattle, then City Center not [appearing on any of the later signs] was that I would follow the signs for I-5 to get to City Center. So it is likely that I would be at the far right lane at this point because it was marked for exit."
• "The previous signs were worse than [providing no information] because the misled you into believing that City Center was in the opposite direction."

The uncertainty leading up to the final set of signs would have also caused some drivers to feel stressed out by the split. Driver responses include the following:

• "What annoys me is that if I'm from out of town, I'm going to end up going in the wrong direction and end up somewhere that is totally unknown to me. Then I don't know how I'm going to figure out how to get back to where I wanted to go."
• "It is very stressful, especially if everyone is going 5 mi above the speed limit."
• "I'm relieved that it's an option lane. Before that, I would be stressed because I'd be thinking: Do I need to [change lanes]?"

Challenges:

Drivers reported multiple challenges related to reading the sign information and also with regard to the situation in general.

Sign Reading:

Many drivers identified sign elements that would have made obtaining the information they need from the signs more difficult. These challenges included too much information, mismatched expectations causing them to look for information in the wrong place, and distracting information that was not central to their navigation task. Driver responses include the following:

• "There's too much to read."
• "There are so many signs, even if you have time to read them, you are never going to have enough time to decide what to do here."
• "I look for City Center, but in this situation it's not where I expect it to be. So that starts me looking at the other signs, and I'm looking at a bunch of junk that I don't need to be looking at."
• "Seeing the OMSI sign with the different background really distracted me, since I hadn't seen anything about it before."
• "I just noticed that the Seattle sign says 30 on it, which makes it even more confusing, since I thought 30 would take me to City Center. If you were fixated on the 30, you might have read the wrong sign."

Many drivers also discussed the challenges caused by the geometry of the interchange, in particular, the limited sight distance and sign reading time that occur because the split happens almost immediately following a blind curve under an overpass. Driver responses include the following:

• "Putting the signs up just beyond those curves like that makes them impossible to see until it is almost too late."
• "I'm a very visual person, I thought that rounding the corner is really deceiving because all of the sudden you have to make a decision. The corner really throws me."
• "Because of the curve to the right, if you are in the right lane and want to get to the left it makes it even more scary."

Situation-Specific Challenges to Navigating the Split:

Many drivers had comments related to several factors that made navigating the split particularly challenging. Comments on limited time include the following:

• "There's not enough time to make that decision, especially with traffic and distractions."
• "I think you are pretty much prepared that there is a split coming, but in terms of finding out which lane you have to be in, not really. It's too late."

One driver commented on incorrect direction assumptions, "I didn't have a good picture of how this would turn out. Now I'm scrambling to figure out what I have to do with no time to do that. Luckily, I'm already in the [correct] lane, but I still don't like being in this situation."

Comments on multiple required subtasks include the following:

• "You come up out of that last [blind] curve, and you have a very short amount of roadway-a very small timeframe-to read all that information and change lanes if you have to. There's not enough [distance] to make a safe lane change at that point because you have to read it, make a decision, look to see if you are clear, before you reach the [gore point]."
• "Finding what you need from the sign is just one part of this. Then you have to decide, can you do this, can you accomplish the maneuver? Or do you just decide that you can't and try to find another route."

Comments on required awareness of other vehicles include the following:

• "You have to be alert. This comes up on you so fast. You have to be aware of traffic around you, you have to be ready to switch lanes quickly, plan to have room to switch lanes if you can, or hope that someone will let you in."
• "You also have to watch out for other drivers. You always see someone trying to make these last minute lane changes with no consideration for others on the road."

Improvements:

Some drivers had ideas for improvements that would state/verify their split direction, but they generally acknowledged that the option lane was fine. Driver responses include the following:

• "The original sign is accurate because the center lane splits. Back then, I would have appreciated knowing ahead left."
• "A big logo or insignia on the pavement saying which lane to go to City Center would be very helpful here."

Driver Actions:

Despite the challenges of navigating the interchange split, some drivers would try to get into the correct lane to City Center even if they were in the rightmost lane. From any lane, they would only have to maneuver over one lane or just steer to the left (if they are in the option lane). However, they acknowledged that there could be risks associated with their actions. Driver responses include the following:

• "What I would do would depend on how much traffic there is. You only have to navigate one lane-you can usually manage."
• "I would try to veer left if I could do it without getting into an accident."
• "I was ready to peel off right. I'm still in the correct lane, but I may have already started to curve to the right. Now I'm swinging back over."
• "I would have been in the right lane and cut somebody off [trying to get to the center lane]."

One driver also commented on how driver reactions to the split had implications for safety at this location and stated, "Since these signs are only visible at the last minute, you have several drivers making decisions at the same time. Chances are someone may decide that they are in the wrong lane and try to change lanes when it's not safe to do so, and [that could lead to crashes]."

Several drivers also reported different coping strategies for similar interchange-driving situations. Driver responses include the following:

• "In this [location], I'd expect to see someone going slow with their turn signal on, trying to get in the [correct] lane."
• "I would probably just end up going in the wrong direction and trying again."
• "When I travel to someplace I've never been before, I always give myself an extra hour to take care of things like this [missing an exit]."
• "I usually have a passenger with me. I get them to help me out with the signs."

Scenario 2 Key Themes

Some of the key themes expressed in scenario 2 are as follows:

• Even simple diagrammatic signs can be misinterpreted by drivers if the interchange they depict is confusing or unfamiliar to the driver. Option lanes or changes in the number of lanes at different points along the interchange may contribute to this likelihood.
• Drivers who are unfamiliar with an area appreciate feedback that they are in the correct lane or have not missed their exit.
• Drivers seem to actively construct a mental model of the interchange as they encounter sign information or other cues. If they are missing information they need, they may adopt a "wait-and-see" attitude. Otherwise, they will make assumptions about missing information based on the information available (e.g., pairing City Center with Seattle directional information). However, drivers may not be comfortable doing this.
• Some drivers appreciate consistency in sign types.
• Drivers like knowing distance information for upcoming exits.
• A default driver strategy in the face of uncertainty is to drive in a lane that has options or that is easy to change out of into other likely destination lanes. In some sense, there may be a tradeoff between increasing the likelihood of making a one-lane/simple lane change but decreasing the likelihood of having to make a two-lane/stressful lane change.

Scenario 3

Before viewing the video for scenario 3, drivers looked at a map of the area with their intended maneuver marked (see figure 36). This map helped provide some directional orientation that would normally be present if they were actually driving.

©2011 Google^®; map annotations provded by Battelle (see "Acknowledgements")
Figure 36. Illustration. Map of scenario 3 roadways and maneuver.⁽³⁸⁾

Roadway Description

The roadway was the lower deck of a bridge in Portland, OR (coincidentally, the same bridge that was driven in scenario 1). The bridge deck had four lanes, all traveling in the same direction. The bridge was fairly enclosed by support pillars on either side of the roadway. Figure 37 shows an aerial view of the roadway.

©2011 Google^®; map annotations provded by Battelle (see "Acknowledgements")
Figure 37. Photo. Aerial view of scenario 3 roadway.⁽³⁹⁾

The extent of the video footage is shown as a solid yellow line, and the remainder of the intended route is shown as a dashed line.

Driving Objectives

Drivers were told that their objective was to get onto I-5S. Figure 38 shows the signs that drivers encountered and the maneuvers that they had to make during the scenario drive. The relative locations of critical points are shown.

Figure 38. Illustration. Sign information and required vehicle maneuvers in scenario 3.

Scenario 3 Critical Point 1

After merging onto the bridge deck, drivers saw a bank of signs overhead (see figure 39). There were four lanes, with the two leftmost lanes being the continuation of a separate entrance ramp that merged onto the bridge at the same time. The lane markings for the rightmost lane indicated that it was an exit only lane.

Figure 39. Photo. Image presented to drivers for discussion in scenario 3 critical point 1.

Key topics in the group discussion for this critical point included the following:

• Drivers' feelings and strategies given that no information about their destination was provided by the guide signs.
• Drivers' lane choices.

Response Booklet Question

At the first critical point for the third interchange, drivers were anticipating exit information, but their destination was not listed on any of the signs. They were asked which lane they would feel most comfortable in without sign guidance for their destination. Figure 40 shows the lane choice options as they were numbered in the response booklet.

Figure 40. Illustration. Lane numbers provided in response booklet for scenario 3 critical point 1.

Figure 41 shows the distribution of responses. Most drivers were comfortable in lane 3, although a few drivers chose lane 4. There were no notable age differences between responses.

Figure 41. Graph. Booklet response distribution for scenario 3 critical point 1 (N = 107).

As a follow-up question, drivers were asked why they would be most comfortable in the lane that they chose. The top responses for lane 3 are as follows:

• Exits are usually to the right.
• Drivers avoid the exit only lanes.
• Drivers head toward I-5 and hope that a right-hand exit for south appears.
• "South" should be to the right according to the map.

The top responses for lane 4 are as follows:

• The right-hand lane should head south.
• The map suggests that the route toward the south is to the right of the current direction.
• Drivers remembered seeing the hospital on the map, so they followed the signs there.

These responses are largely consistent with the discussion themes from this critical point, which are summarized following sections.

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Sign Interpretation:

The overhead signs provided arrow-per-lane information (see figure 42). None of the signs provided any information about the drivers' destination at this point.

Figure 42. Photo. Guide signs associated with scenario 3 critical point 1.

The absence of information about the drivers' destination in the first bank of signs was obvious to drivers, and it prompted a variety of reactions including frustration and thinking that they may have missed their exit.

Some drivers found the destination information provided by the signs to be inadequate for getting to I-5S. Driver responses include the following:

• "I don't see that these signs apply. Hopefully, there is another one [about I-5S] down the road."
• "These signs are not good. They don't say which way to go for I-5S."
• "The signs don't give enough information to know which lane to be in."

A few drivers expressed frustration that I-5S destination information was left out while information about other destinations was provided. Driver responses include the following:

• "It makes me frustrated immediately. Knowing that I-5 is my destination, and I see signs for every other destination, except a major highway, that's pretty frustrating."
• "I'm disturbed because there is so much emphasis to I-5N but not South at all."

The absence of expected information made several drivers think that they had missed the exit or gotten lost. Driver responses include the following:

• "I would have thought that I was lost, because I see signs for I-5N but not I-5S, at that point I would think that I was going the wrong way."
• "I would think that I would have to turn off to get to I-5S, and somehow I missed the exit."

Expectations and Strategies:

The key expectation in this critical point is related to where drivers expected the exit to occur. Given that this information was not present in the first bank of signs encountered, drivers relied on other bases for these expectations. Some drivers expected a right-side exit based on general previous experience with interchanges. Driver responses include the following:

• "My assumption is that there is a right-hand exit on the bridge. Most exits are off to the right, so that is what I would assume in this case."
• "My assumption was, without seeing it, that I was in the middle lane going to exit right."
• "Because left exits are not as common, there should have been some warning on the [initial set of signs] about where that exit is."

Several drivers reported that their expectations about which side the exit was on were based their general sense of direction. Driver responses include the following:

• "It's counterintuitive to get onto I-5S on the left because that means you are going to travel north to go south. I would have guessed that I would be exiting on the right."
• "Just by default, I'm going to be in the right lane because I'm going to assume that the off ramp is going to go towards the direction of the freeway you are going to. Not the opposite way."
• "I'm thinking I'm going right. If you are going North East and you want to head to the South, you are going to turn right."

Some drivers formed their expectations about the direction of the exit based on the spatial relationships seen on the initial map. Driver responses include the following:

• "I would've stayed in the [right middle] lane. From the map, South is to the right, so I would assume that the exit would be to the right."
• "From looking at the map, you know logically that 5 South is to the right."
• "My reaction was to get into the far right lane because my assumption looking at the map was that the Exit Only lane would lead to I-5S-bound, even though it did not say so."

Challenges:

The sense of being in a confined space on the bottom bridge deck made a few drivers uncomfortable. Driver responses include the following:

• "I don't like bridges either, so I'm already concentrating on being on a bridge without having to think about looking for other signs too."
• "I think it is dangerous to have to look all the way to the right. The bridge deck gives you tunnel-vision and you just want to look straight ahead."
• "With double-decker bridges, I kind of take it for granted that they are always confusing. They always have the signs in funny spaces, and they are difficult to see past those beams there. When I drive this I just tell myself: It's going to be confusing, it's going to be horrible, but I'll make it."

Improvements:

Drivers had opinions about where freeway exit information should be displayed. Many of them suggested that placing the information above the eventual exit lane would be helpful. Driver responses include the following:

• "They could have had something that said "The Dalles" and "I-5S" on that sign [on the left], so you would know to look for that."
• "If the sign only has that much space, I think it would be better to leave "The Dalles" off in order to put 5 South on."
• "Even if they don't have any words, just I-5S with an arrow."

Many drivers suggested placing I-5S information near the I-5N information. Driver responses include the following:

• "They could have said I-5N and South on the middle sign. Or, added ‘I-5S left lane.'"
• "Why didn't they put the I-5S on the left side of the sign and the I-5N on the right side of the sign? And then you're splitting [tilted] arrows."
• "They don't need 3 feet of green on either side of the Seattle. They could've made the [I-5N for Seattle] sign a little bit smaller so that there would be room on the other sign to put on the I-5S."

Driver Actions:

Several drivers reported inherently trusting that they will get the information they need eventually (in enough time to make a decision) and that they are willing to continue down the road until they get it. Driver responses include the following:

• "Sometimes what I do in a situation like this when I don't see signs for my [destination] is keep going towards the highway [I-5N in this case], hoping that there is going to be signage for my destination eventually."
• "I'd stay in a neutral lane, like one of those two that say I-5N, because the other two are exit lanes, and assume that you're going to be provided with me instructions later."
• "If nothing makes sense on any of the signs, keep going straight until something does."

Some drivers were prepared to exit the freeway to get better directions if necessary. Driver responses include the following:

• "Exiting right away [even if it is the wrong exit] can save you time because if you are continuing in the wrong direction, you don't know when the next exit is. So you might as well take the first exit, get things straight [by asking directions,] and get back on track."
• "I figured, I'd take the right lane, and exit, check the map again and look for signage around the exit since there was nothing to indicate I-5S."
• "I would just get off the freeway."

Several drivers reported adopting a "hedging" strategy in which they stayed in the middle lane, allowing them to make lane changes if needed. Driver responses include the following:

• "I would stay in the middle lane because that would give me some options up ahead as to what lane I needed to be in…until I found the next sign."
• "I would stay in the middle lanes, so you can go right or left."
• "I try to stay on the inside lanes. I don't go in the hammer lane, and I don't go in the outside right-hand lane."

In absence of navigation information, a few drivers used landmarks (i.e., from the map) to get a sense of the exit direction. Driver responses include the following:

• "I would go ahead and get in the far right because I have this flash on the map of seeing this H for hospital. I have North, I don't have South, but I know the hospital is that way (to the right). So my inclination would be to get to the far right and follow the hospital signs."
• "I always look for landmarks. And when I had my trusty map, I saw a hospital. So when I saw a sign that said "Hospital, Kirby Avenue," I chose that lane to be in to make my exit."
• "If I was looking at the map again or trying to glance at it while driving, the Kirby Hospital is close to that interchange, so my assumption would have been to stay in lane 3 [middle right]. Hopefully then I'm either still going to be close to the exit for the hospital, which looks like it's taking me in the general direction that I'm going, or there is going to be a sign for I-5 coming up."

A few drivers also used a similar approach to get a sense of the distance to the exit. Driver responses include the following:

• "I wouldn't think that the hospital exit will take me to I-5S, but I'd still use it as an indicator that my exit is coming up."
• "I know the hospital is before where I want to go, it looks like a little local exit just to get off the bridge, so I'm staying in [the third] lane, waiting for my exit to come."

Scenario 3 Critical Point 2

At this critical point, drivers encountered identical guide signs on the left and right bridge supports (see figure 43). The exit for the driver's destination (I-5S) was on the left.

Figure 43. Photo. Image presented to drivers for discussion in scenario 3 critical point 2.

Key topics in the group discussion for this critical point included the following:

• Drivers' opinions about the placement of the signs.
• Drivers' opinions about multiple lane changes.

Response Booklet Question

At the second critical point, drivers viewed side-mounted guide signs that indicated I-5S and "The Dalles" would be exiting to the left. They were asked what surprised them about the required maneuver. The responses were categorized into seven categories, which were then ranked by response frequency (see table 7).

Table 7. Rank of booklet responses for scenario 3 critical point 2 (N = 92).

The most commonly mentioned surprising element was that the exit was on the left. This surprised drivers for two reasons: (1) the map set up their initial expectation for a right exit and (2) most exits are on the right-hand side of the roadway. The next two most common responses relate to the destination information provided-that there was no previous indication of I-5S and the inconsistency of the destinations provided between the various sets of signs. Drivers were also surprised by sign placement and that the same sign information was in two different locations. The third most frequently reported surprising element was how little time drivers had to get over to the exit lane at that point.

Focus Group Discussions

The key themes covered during the discussion of this critical point are summarized in the following subsections.

Sign Interpretation:

The guide signs on either side of the roadway provided the first information to drivers about the location of their exit, which was on the left (see figure 44). The I-5S information was provided with other destination information and was not as easy to see as the other elements.

Figure 44. Photo. Guide sign associated with scenario 3 critical point 2.

Sign Placement:

Many drivers expected better consistency with regard to the placement of consecutive signs. Driver responses include the following:

• "I would have expected to see the signs in the same place [overhead] as I did before."
• "When you first came onto that bridge area, it always set the precedent of signs are above, so you're going to keep looking above."
• "The signs have all been overhead and I wouldn't be looking to the sides necessarily."
• "I believe in consistency. Then you know where to look. If it's been overhead, they should keep it overhead."

Some drivers had concerns about the possibility of missing signs because of low visibility or occlusion by other vehicles. Driver responses include the following:

• "There could have been a truck there and you wouldn't even see it. If you're in a regular car and there's an SUV, you probably wouldn't be able to see it. And if it's a semi and it goes on and on and on, you'd miss your chance to see it."
• "This is a perfect world setting as far as traffic, but if you've got all of those lanes filled or you've got a tractor trailer driver on that extreme left, you're not going to see that sign at all."
• "Those could be tough to see of the weather was bad."

A few drivers observed that sign visibility could be reduced because they exist outside the normal field of view. Driver responses include the following:

• "The signs don't even appear to be within the travel lanes. They appear to be outside the field of view. I wouldn't expect to see any important signs in those locations."
• "You are not looking to the sides, you are looking ahead."

Sign Information/Elements:

Some drivers expected information about major destinations or freeways to be prominently displayed and that the I-5S symbol was not only small, but also overshadowed by other sign information. Driver responses include the following:

• "I wouldn't be looking for a sign for I-5S there because the sign for I-5N was so prominent."
• "My impression is that we would hit the exit for the north, and then the south would be next, and it would also be marked in the same fashion."
• "If you were looking at the sign on the right and just looking for I-5S, you might not read the whole sign and associate it with [an exit on the right side]."

Some drivers also reported some confusion caused by seemingly unnecessary or unexpected information elements as follows:

• "If I saw these two signs on either side of the road, my brain probably wouldn't even register them because I would see that they both say ‘The Dalles' [and I'm not looking for The Dalles] and that's in large letters and South is very small letters. They should also put the word "left" larger than anything."
• "The Dalles is very prominent on that sign, but that's not going to help me. And I-5S is really tiny."
• "I see I-84 and then I see I-5S next-the previous sign just said I-5N-I wouldn't expect to see I-84 before I see I-5S. That's not the way it appears on the map. You get to I-5S before I-84."
• "Where did I-84 come from?"

Redundant Signs:

Some drivers also felt that providing two identical signs was potentially more of a distraction than a benefit. Driver responses include the following:

• "It's a bit of a distraction. I would want to know, does [the left-side] sign say the same thing as the [right-side] sign? If I'm looking for I-5S and I haven't seen it, then I'm going to want to know what do both signs say? You'd be wondering, did I miss something?"
• "The fact that there are two of them, if you don't know that they are the same sign you may waste time looking at both of them when you don't have to."
• "If you're trying to look at both signs, you might miss the exit."

Expectations and Strategies:

Some drivers would have expected that being in the right middle lane was the most logical choice, given the lack of useful guidance information. Driver responses include the following:

• "Lane 3 [center right] is the only logical lane to be in because you don't want to go to Dalles, you don't want to go north, and you don't want to get on Kirby Ave. So what other option do you have?"
• "I would have been in the third lane because the outside lanes are both exiting, so I would expect my exit to be further ahead. And I would assume that the odds are I would have to exit right."
• "With two lanes clearly marked as exits on either side, I'm going to stay in the middle."
• "I expect Kirby Ave to come before I-5S, so I would not get in the far right lane."

Several drivers expected and would have liked to receive distance information to help them decide whether to attempt the multiple lane changes. Driver responses include the following:

• "If [the sign] had said half a mile or 200 ft-if you knew, it might give you a little help whether to cut three lanes over."
• "I'm not sure at this point it would register to me how fast the exit was coming up, because it also doesn't say that anywhere. From this perspective, I might have trouble seeing that exit. So I think I would try to get over, thinking I probably have more room than I actually do."
• "This would have been a perfect time to give distance [information], so you know that I-5S is coming up right away."

Driver Actions:

Drivers reported that they would respond to last-minute multiple lane changes in a variety of different ways, often depending on the driving conditions. Some drivers reported that they would slow down to give themselves more time to execute the maneuver, while others hoped that adjacent drivers would let them into the lane. Driver responses include the following:

• "I'd slow down to try to give myself enough time to get over."
• "I would immediately slow down and then figure out where I should go."
• "I would just slow down and put my blinker on until somebody let me over. I may end up 10-15 mi/h under the speed limit, but eventually, someone lets me over."
• "I'll slow down until someone lets me in."

Most drivers would attempt to get to the exit if traffic was light enough. Driver responses include the following:

• "I might try if it's this light of traffic."
• "I'd try to move over, if it seems safe."
• "If there were no other cars with you, you get to the left exit."

A few other drivers acknowledged the challenges caused by other traffic. Driver responses include the following:

• "I was expecting to be turning off to the right, so now I'm going to be trying to get to the left in traffic that is probably going 10 mi/h faster than I am because they know where they are going. I don't like that."
• "You could confuse or upset other drivers, and cause road-rage on their part."

There were also a few drivers who would just keep going to I-5N, turn around, and get onto I-5S coming back. Driver responses include the following:

• "If it was clear, I'd try to make my way in. But if there was a lot of traffic, I'd just keep going."
• "It depends on traffic. The safest thing to do is pass it and find your way back."

A few drivers recognized that they simply would not have made the exit. Driver responses include the following:

• "I tend to drive on the right because I tend to drive slowly. I would have just missed that exit."
• "If I clearly understood that sign and realized what I had to do, yes I would do it. But the likelihood of me putting that all together in time is probably not great."
• "Here, you don't know that the exit is to the left until you're almost there, and in heavy traffic, you don't have room to safely change lanes, turn on your turn signal, check your blind spot, and do that twice before you're on that exit."

Multiple Lane Changes in General:

Drivers also provided opinions about multiple lane changes at interchanges in general. In particular, they recognized several considerations that would influence whether or not they would decide to make a lane change.

Influencing Factors:

Many drivers reported being influenced by whether or not traffic volume and speed allowed for multiple lane changes. Driver responses include the following:

• "In rush hour traffic, it's really, really hard [to make multiple quick lane changes]."
• "It depends on the traffic. I think it is very dangerous when you are in traffic."

Several drivers described the safety-related considerations of making multiple lane changes. Drive responses include the following:

• "I would go into serious mode of blind spots, looking, merging, thinking, trying to assess if I can make it over there safely, if someone is going to let me in, because there comes a point where I just let it go, I'm not going to make it."
• "There's other times where you just have to say "I missed it, oh well, if I come back that way again I'll know what to do" but let me just go up an exit, turn around, and continue on my way. It's too dangerous; we should never be in that much of a rush."
• "I'd check to see if there was enough room to get over, and if there wasn't, I'd have to do a back-track, rather than risk my life just to get over."

A few drivers considered the distance available.

• "If there is adequate space, then they are fine. A mile or two to get over a couple lanes-that's fine, you have time to do that."
• "I like a lot of distance [when making lane changes]. At least three cars from me, so I can make sure I can get over and still have a [safety envelope]."

Challenges:

Drivers also identified several factors that can make multiple lane changes more challenging. A few drivers felt that multiple lane changes to the left were more challenging than to the right. Driver responses include the following:

• "When you are making a change to the left, you have to realize that that is the fast lane you are pulling in front of."
• "The big difference for me is on the left versus on the right. If [multiple lane changes] happen on the right, I would be expecting that and be ready. But on the left I would not be expecting that. For me, it feels more hazardous."
• "It's hard if you are moving left than if you are moving right. It's harder to turn to look around for other traffic [in that direction]."

A few drivers mentioned the influence of other merging drivers. Driver responses include the following:

• "There's always going to be somebody who's going to try to get over when it's not safe. So that's the other thing when I'm in that situation that I'm thinking is, oh no, who's going to come and slam into me."
• "A lot of people don't seem to know how to merge in traffic, so they will slow down to almost nothing. That causes congestion, and the whole thing backs up."

One driver noted that poor weather increases the difficulty level and stated, "Rain and poor weather would also make it harder."

Also, one driver mentioned that unfamiliarity with the interchange or driving at night would make the maneuver more challenging. The driver indicated that, "[Multiple lane changes] are challenging, especially if you don't know where you're going, or you're unfamiliar with the area, or it's at night."

Several drivers commented on how stressful they perceive multiple lane changes to be. Driver responses include the following:

• "It's extremely stressful, especially in short distances, heavy traffic, when you're going fast."
• "For stress, I'd give [multiple lane changes] a 10/10."
• "If it's at the last minute, it usually makes me feel nervous."

A few drivers also found multiple lane changes effortful. Driver responses include the following:

• "It forces me to concentrate all my attention on driving and think logically about what I'm doing. That's when I tell my passengers that I need to focus on what I'm doing."
• "You have to watch for traffic to your [side] and behind you for more than one lane. That's a lot of people you have to watch."

A few drivers also reported a general dislike of multiple lane changes. Driver responses include the following:

• "They're the worst. I think they're the most likely to cause accidents."
• "If I have to make multiple lane changes, I don't think someone was doing their job. The job of the engineering should be to plot out the course to let the driver know what's coming up and what they have to do to maneuver get where they have to go."

A few other drivers reported going out of their way to avoid interchanges with multiple lane changes. Driver responses include the following:

• "I know for myself, particularly as I get older, I will purposefully just avoid certain times of day. I don't even want to get a job downtown. I don't want to be in this situation."
• "Every time you do it, your stress level gets really high. I tend to use a different entrance just to avoid that."
• "I usually find that if I'm driving somewhere and I have one of those [multiple lane changes], I often just avoid them and do a different exit. I hate those."

Scenario 3 Key Themes

Some of the key themes expressed in scenario 3 are as follows:

• Drivers have an egocentric view of interchange information. They want information about their route to be clearly available, and they may perceive information about other routes to be a distraction if it interferes with information about their route. They do not seem to be very aware of the trade-offs that engineers must make regarding what information gets displayed.
• Directional relationships among roadways (e.g., from maps, location of landmarks, or cardinal direction) may also represent another source of expectations for exit location. This is probably not something that overrides the expectation of a right exit based on what drivers typically experience; however, it might suggest that left exits that also have these directional mismatches could benefit from special consideration.
• Drivers place a certain amount of trust in the idea that interchange signage will provide the information they need in a way that still gives them enough time to do what they have to do. If they do not see the information they need, they are willing to continue without it for a while. However, this trust erodes as they go longer without seeing the information they need.
• Drivers can determine information they do not get from signs. For example, for the I-5S exit, they used cardinal direction, landmarks, and other destinations/exits to obtain proximity information.
• Drivers have expectations regarding what and how destination information is presented. For example, major freeways should be prominent, and different directions of the same freeway should be treated similarly.
• Some drivers are less comfortable making lane changes to the left than to the right. Because they are merging into a lane with faster traveling vehicles, it feels more hazardous. There are also concerns about visibility/blind spot checking.

Task 4 Conclusions

Drivers expected that there would be functional relationships between lanes on the roadway and arrows/text on signs and that the signs themselves would make these relationships clear. For example, when looking at signs with arrow-per-lane information, drivers interpreted the arrows as corresponding to information that was directly above or grouped somehow with the arrows. In scenario 1, this led to an unnecessarily restricted view of which destinations were served by each lane. This tendency to look for relationships also occurred with other sign information such as route shields and exit only plaques. Additionally, option lane arrows created more work for drivers since they had to discern that multiple destinations could be reached by a single lane, which branched into different directions.

Drivers expected that the distance between a guide sign and a final (or last chance) decision point would be sufficient to allow for making any necessary lane changes in a safe and timely manner. Moreover, drivers utilized distance information for upcoming exits so that they knew how much time they had to make a lane change.

Drivers expected that they would have more than one opportunity to obtain necessary destination and lane information before they needed to make a final decision regarding lane choices. A second opportunity to see the same information may also serve as a confirmation for drivers. Unfamiliar drivers in particular may appreciate feedback that they are in the correct lane or have not missed their exit.

Drivers expected that that the freeway system would provide them with the necessary information to construct a mental model and that it would be sufficient to support timely and accurate decisions about lane choice. Drivers seemed to actively create a mental model of the interchange as they drove through it. If they were missing information that they needed, they may have adopted a "wait and see" attitude, making assumptions about the missing information or filling in the information using supplementary information that was available about the area (e.g., cardinal directions, landmarks, etc.). Drivers generally trusted that the information that they needed would be provided to them in enough time to act.

Drivers expected that the information available to them through the freeway system would be sufficient to support decisions about lane choices so that they would never have to move over more than one lane at the last moment. Drivers trusted that they would get the information that they needed in a timely manner. However, in the face of uncertainty or unfamiliar surroundings, some drivers adopted a strategy of staying in an option lane where it would be easy to change into other likely destination lanes. This shows a tradeoff between increasing the likelihood of making one lane change while decreasing the likelihood of making multiple lane changes. Other drivers preferred the certainty associated with using exit only lanes.

Drivers expected that the freeway system would provide sufficient information to support decisions about all route choices, not just frequent or popular choices. Drivers tended to have an egocentric view of destination information; they want their destination information to be clear. Additionally, when the set of destinations listed on a sign changed (destinations were added or removed from a series of guide signs), drivers became uneasy.

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