Driver Attitudes and Behaviors at Intersections and Potential Effectiveness of Engineering Countermeasures
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APPENDIX D. TABULAR SUMMARY OF THE FOCUS GROUP RESULTS
RESULTS TABLES TERMINOLOGY
For each scenario and countermeasure, the participants discuss a set of questions or themes. Key discussion points and opinions for each of these questions or themes are presented in table format after the text. Tables are organized into three columns containing information about:
Group: The first column lists the set of respondents (based on age group or geographic location) that predominately held the opinion expressed.
Opinion: The middle column summarizes the opinion or response.
Strength: The last column presents an approximation of the proportion of respondents from the indicated group (first column) that shared the opinion.
Group identification
The group column uses the following terms individually or in combination to indicate which set of participants held a particular opinion.
Older |
Respondents in the older groups from all locations |
Middle-aged |
Respondents in the middle-aged groups from all locations |
Young females |
Respondents in the young female groups from all locations |
Young males |
Respondents in the young male groups from all locations |
All |
The opinion was generally held by all groups and no sub-set of groups stood out in terms of the number of participants sharing that opinion |
Younger |
Respondents in both the young male and young female groups from all locations |
City name |
Respondents from all groups at the indicated focus group location (Washington, DC, Chicago, or Seattle) |
Strength Quantification
The strength of opinion was described using the following ordinal scale:
One < Few < Some < About Half < Many < Most < Almost All
These measurements should be taken as a general approximation, and in many cases are based on the focus group moderator’s impression of how many focus group participants shared a particular opinion. Where possible, the video recordings were used to generally confirm these magnitudes.
In some instances, more specific measurements are indicated (e.g., 1/3, 1/5, etc.). These measurements are based on more direct measurements, such as hand counting, or by specifically asking each participant.
In a few instances in which the same opinion was shared by different proportions of individuals from each group, the following syntax is used in the Group and Strength columns:
Table 12. Syntax for Group and Strength columns.
Group | Opinion | Strength |
Group1 / Group2 |
| Magnitude 1 / Magnitude 2 |
In this case, which group goes with which magnitude is indicated by the order of the terms relative to the "/" marks. In the example above, Group 1 goes with Magnitude 1, and Group 2 goes with Magnitude 2.
Scenario 1: Red–Light Running
Approaching a signalized intersection at speed, the light turns yellow. The driver is far enough away from the intersection that he/she can stop if he/she brakes hard, but is likely to enter the intersection on an early red if he/she accelerates.
Table 13. What are drivers most likely to do in this situation (scenario 1)?
Group | External Factor | Strength |
Older |
- Stop at the intersection.
| Almost all |
Middle-aged |
| About half |
Young female |
| About half |
Young male |
| Three-quarters |
Young male |
- Go through, even if the light just turned red instead of yellow.
| Some |
Table 14. What factors influence driver decisions to stop (scenario 1)?
Group | Factors That Incline Drivers To Stop | Strength |
Older |
- Stopping is their default strategy.
| Most |
Older |
- They make an automatic assumption that the lead vehicle will stop (even if this is unlikely).
| Most |
Older |
- The longer the light is yellow, the more inclined they are to stop.
| Some |
Middle-aged |
- The possibility of crashing into the lead vehicle if it decides to stop suddenly.
| Many |
Middle-aged |
- If they think that there could be red-light cameras or police in the area.
| Some |
Young female |
- Often use predetermined criteria based on several factors including roadway type (urban/rural), traffic volume, and pedestrian density.
| Many |
Young female |
- If lead vehicle looks like it will stop or turn right.
| Many |
Young male |
- If the lead vehicle looks like it will stop or turn at the last minute.
| Many |
Young male |
| Many |
Young male |
- Having to speed up too much to get through.
| Some |
Young male |
- Rush-hour synchronized traffic signals because they would just have to wait at the next light if they went through the current one.
| Some |
Table 15. What factors influence driver decisions to go through (scenario 1)?
Group | Factors That Incline Drivers To Go Through | Strength |
Older |
- The risk of getting stuck encroaching into the intersection if they cannot stop in time.
| Some |
Older |
- Not wanting to get rear-ended if they did stop.
| Many |
Middle-aged |
- Going through is the default strategy, unless they think that they do not have enough time to get through.
| Some |
Young female |
- Often used predetermined criteria based on several factors including roadway type (urban/rural), traffic volume, and pedestrian density.
| Many |
Young female |
| Many |
Young female |
- Sparse traffic/off hours (evening/early morning).
| Some |
Young female |
- Frustration at traffic volume.
| Some |
Young female |
- If the vehicle behind them is following too closely.
| Some |
Young male |
- If the lead vehicle is going through.
| Many |
Young male |
- If they would otherwise have to slam on their brakes to stop.
| Many |
Young male |
| Many |
Young male |
- Rush-hour synchronized traffic signals because if they miss the current light it will make them miss the timing for the next several lights.
| Some |
Table 16. What are some additional external factors that influence driver decisions (scenario 1)?
Group | External Factor | Strength |
Middle-aged and younger |
- Having passengers in their car, especially children.
| Many |
All |
- Type of person driving the car in front or behind them (specifically, whether they appear likely to go or stop on a yellow light).
| Some |
All |
- Age, type, and/or cost of vehicle in front.
| Some |
All |
- Transporting a dog (that is not restrained).
| Some |
Table 17. Do drivers anticipate and plan a response for a dilemma-zone situation as they approach an intersection, or do they react on the fly to the yellow light and the corresponding driving conditions (scenario 1)?
Group | Response | Strength |
Older |
- Likely to plan ahead and anticipate a response.
| Most |
Middle-aged |
- Likely to rely on "gut" or instant decision without any prompting.
| Most |
Younger |
- Likely to plan ahead and anticipate a response.
| Many |
Younger |
- Likely to rely on "gut" or instant decision without any prompting.
| Some |
Table 18. What other information do drivers use when making decisions regarding going through or stopping (scenario 1)?
Group | Other Information | Strength |
All |
- Pedestrian signal status to anticipate the light change.
| Some |
Middle-aged and younger |
- Familiarity with intersection, specifically if they know it is a long light or has a long yellow phase.
| Many |
Older |
- Lane markings (if they become solid).
| One |
Table 19. Is going through the light ever a deliberate act (scenario 1)?
Group | Frequency and Reason Why | Strength |
Young males |
- Sometimes, just to "try to make it" or based on mood (aggressive, frustrated, or rushed).
| About half |
Young females |
- Sometimes, just to "try to make it" or based on mood (aggressive, frustrated, or rushed).
| About a quarter |
Older |
- Sometimes, just to "try to make it" or based on mood (aggressive, frustrated, or rushed).
| Few |
Middle-aged and younger |
- Sometimes, to avoid slamming on the brakes or being rear-ended.
| Many |
Table 20. Is it ever the case that drivers do not notice the signal until it is too late to do anything but continue through the red? Do drivers ever try to stop in this case (scenario 1)?
Group | Frequency and Reason Why | Strength |
Young males |
- Rarely—but if distracted, they just go through.
| Some |
Other than young males |
- Rarely—decision to go is based on their assessment of how safe it is to stop.
| Some |
Table 21. Complicating factors (scenario 1).
Group | Factor | Strength |
Other Vehicles |
All | - They are concerned about oncoming vehicles turning left across their path.
| About a quarter |
Other than young males | - They are concerned about cross traffic ready to enter the intersection at speed as soon as their light turns green.
| Many |
Congestion |
All | - Heavy congestion is a reason for not running lights.
| Many |
All | - Long delays are a reason for running the light.
| Many |
Weather |
Chicago | - Ice and snow are a reason for caution but also for running the light if it means avoiding skidding or losing control.
| Some |
Seattle | - Slick oil with rain is a reason for caution but also for running the light if it means avoiding skidding or losing control.
| Some |
Poor Visibility |
Older/middle-aged | - Poor visibility at night and in bad weather leads drivers to be more cautious and slow down.
| Many/Some |
All | - Vision obstructions from trees, buildings, etc., make drivers more cautious.
| Many |
Glare |
Older | - Glare from certain types of lights (e.g., halogen) is problematic.
| Some |
Seattle, WA, younger | - Glare from sun during the day can be problematic.
| Some |
Poor Traction |
All | - Poor traction makes drivers more likely to go through the intersection rather than risk skidding or losing control of their vehicle.
| Many |
Terrain |
Seattle | - Hills can obstruct their view.
| Some |
Seattle | - Hills would prompt those driving a stick-shift to go through a light to avoid having to stop uphill.
| Some |
Other Factors |
All | - The presence of pedestrians would prompt caution, especially at night when they are harder to see.
| Many |
Middle-aged and younger | - The presence of red-light cameras or police would prompt drivers to be more cautious.
| Some |
| - Proximity to school zones leads drivers to use "extreme caution" at intersections.
| Some |
All | - Their vehicle type and that of the lead driver has different effects based on the vehicle’s ease of stopping (e.g., less with SUV), how much it obstructs vision, and how new or expensive it is.
| Some |
Table 22. What are driver attitudes regarding red-light running (scenario 1)?
Group | Attitude | Strength |
All |
- Those involved in intersection crashes or near-misses view red-light running as being much more dangerous than other drivers did.
| Some |
Older |
- It is a serious problem and something that too many people do without regard for the consequences.
| Most |
Middle-aged |
- Although they typically run yellow lights and sometimes red lights, they do not view their actions as contributing to the problem of true red-light running—that is something others do.
| Many |
Younger |
- It is more of a monetary than safety issue, with their primary concern to avoid traffic tickets.
| Most |
Younger |
- Avoiding getting a ticket is like a game, which prompts them to avoid intersections where they are more likely to get a ticket.
| Many |
Table 23. What do drivers believe are the consequences of running red lights (scenario 1)?
Group | Consequence | Strength |
All |
- Tickets and expensive fines.
| About half |
All |
- Getting into a crash and causing injuries to pedestrians, passengers, themselves, or other drivers.
| About half |
Middle-aged and young females |
| Some |
Older |
| Some |
All |
- Being "at fault" and liable for any crashes.
| Some |
Table 24. Do drivers’ beliefs about the consequences come into play in their decision process (scenario 1)?
Group | Impacts of Consequences | Strength |
All |
- The potential for crashes, hitting pedestrians or getting hit by other drivers makes drivers more cautious and causes them to alter their driving.
| Many |
Older |
- They are not influenced by the possibility of getting a ticket.
| Most |
Middle-aged and younger |
- The presence of cameras and police would cause them to slow down and be more careful.
| Many |
Young males and females |
- Getting a ticket had previously produced only a transient improvement of their safety behaviors, and they often adapt by avoiding intersections where they think they might get a ticket while continuing to run red lights at other intersections.
| Most |
Younger |
- They view red-light tickets as simply the cost of driving and would not try to change their behavior.
| Few |
All |
- The possibility of hitting pedestrians and especially children causes them to be more cautious and slow down.
| Many |
Middle-aged and young females |
- The are most concerned about the impact of their actions on the safety of their passengers, especially young children.
| |
Older |
- Concerns about being "at fault" in a potential crash causes them to drive more safely.
| Some |
Table 25. How does experience with critical events (e.g., crashes, near-misses) impact their decisions, attitudes, beliefs, etc. (scenario 1)?
Group | Impacts of Experience | Strength |
All |
- Impacts were strong but very situation-specific, with increased caution not generalizing to other situations.
| Many |
All |
- Serious crashes involving family or friends cause them to be more cautious in similar situations.
| Some |
Older |
- They are less likely to see themselves as being "at fault," which makes them less likely to change their behavior.
| Some |
Table 26. To what extent is red-light running behavior impacted by perceived social norms (scenario 1)?
Group | Impacts of Social Norms | Strength |
Older and middle-aged |
- They are neither concerned about nor influenced by social norms.
| Most |
Younger |
- They could be influenced by peers to run a red light.
| Few |
Younger |
- They become more cautious and less likely to go through the light if they are driving with their parents.
| Many |
Middle-aged women |
- They become more cautious with their older children in the car because they want to serve as a good role model.
| Few |
Table 27. To what extent is the act of going through the light under their control (scenario 1)?
Group | Aspects of Perceived Control | Strength |
All |
- Going through the light is not under their control.
| Many |
All |
- What they perceive to be deliberately short yellow-phase durations makes it beyond their control.
| Many |
Older |
- Other vehicles coming up behind them too quickly make it beyond their control.
| Many |
Chicago, IL, and Seattle, WA |
- Slippery roadway conditions make it beyond their control.
| About half |
Younger |
- They are the most likely to take responsibility for their red-light-running behavior.
| Some |
Table 28. To what degree, if any, does habit (e.g., "I don’t think about it, I just always do it that way") affect whether or not drivers run a red light (scenario 1)?
Group | Impact of Habit | Strength |
All |
- Going through a red light is viewed as something not done simply out of habit.
| Almost all |
Scenario 2: Left Turns at Busy Intersections
Stopped in the middle of an intersection, waiting to make a left turn on a busy street; an oncoming car is also waiting to turn left and makes it difficult to see other vehicles approaching in the next lane. There is no dedicated turning lane and no dedicated turn signal; cars are waiting behind to also turn left (or go straight).
Table 29. What are drivers most likely to do in this situation (scenario 2)?
Group | Action | Strength |
All |
- Wait for the light to change to yellow or red to get some protection from oncoming traffic.
| About half |
Older and middle-aged |
- Avoid the left turn altogether by going straight, turning right, or planning a different route.
| About half |
Young females |
- Avoid the left turn altogether by going straight, turning right, or planning a different route.
| Some |
Young males/ females |
- Barge their way into the oncoming lane and force oncoming vehicles to slow.
| About 1/4 / Few |
All |
- Wait for the oncoming vehicle to turn, then go if there is no other oncoming traffic.
| |
Table 30. What steps do drivers take in making the turns (scenario 2)?
Group | Action | Strength |
Intersection Entry |
All | - Advance directly to the middle of the intersection without hesitation, regardless of how much traffic is coming.
| Most |
All | - Wait at the stop line until there’s no traffic coming, then inch forward.
| Few |
Vehicle Positioning Within the Intersection |
Older, middleaged, and young females | - If they were going to turn, they would inch forward but stay straight in their lane.
| Most |
Young males | - Position themselves in the lane of opposing traffic or slanted toward opposing traffic (yet protected by the oncoming turning vehicle).
| Most |
Young females and middle- aged | - Position themselves in the lane of opposing traffic or slanted toward opposing traffic (yet protected by the oncoming turning vehicle).
| About a quarter |
Decision to Turn |
All | - They prefer to wait until no traffic is coming and there are no cars in sight.
| Most |
All | - Look for an acceptable gap in oncoming traffic.
| About half |
All | - Wait until the light changes yellow or red.
| About half |
Acceleration |
All | - Check for pedestrians before initiating the turn.
| Almost all |
All | - Accelerate quickly to get out of the intersection as soon as possible.
| Almost all |
All | - They feel uncomfortable when they go because they are concerned that they missed something or misjudged the gap.
| Many |
Table 31. How do drivers decide (what steps are involved) whether or not a gap in traffic is sufficient (scenario 2)?
Group | Response | Strength |
How Decision Is Made |
All | - It depends on the speed and distance of oncoming traffic.
| Most |
All | - They watch oncoming cars go by and try to gauge the time it takes to close the distance between themselves and the oncoming cars.
| Some |
All | - They judge the gaps until they feel comfortable with enough distance to make a move.
| Some |
All | | Some |
Factors That Directly Affect Gap Judgment |
All | - Familiarity with the intersection increases the likelihood that they will accept a smaller gap.
| Some |
Older/young males | - The presence of passengers makes them more cautious and more willing to wait longer for a safe gap.
| Many/ Some |
Table 32. What other information or considerations come into play (scenario 2)?
Group | Action | Strength |
All |
- They take advantage of the oncoming vehicle making its left turn to get a better view of oncoming traffic.
| Most |
All |
- They watch out for oncoming vehicles potentially going straight through from behind the oncoming turning vehicle, even when light is yellow or red.
| Some |
All |
- They look for turn signals in oncoming traffic behind the oncoming turning vehicle to make sure there will be no conflict when they try to turn—however, they do not always trust the signal.
| Some |
Table 33. What are some of the strategies that drivers use in this situation (scenario 2)?
Group | Action | Strength |
All |
- They try to make eye contact with oncoming drivers.
| Some |
All |
- They look through the windows of the cars to see if they can get a better view.
| Some |
All |
- They make sure they are out far enough into the intersection so the other cars will see them and have to let them go when the light turns yellow or red.
| Some |
All |
- They get passengers to "spot" for them.
| Some |
Table 34. Complicating factors (scenario 2).
Group | Factor | Strength |
Other Vehicles |
All | - They do not care about the cars behind them; however, about half still have strategies for addressing following vehicles in one way or another.
| About half |
All | - They ignore following vehicles that start honking.
| About half |
Older/young females | - They are concerned about following vehicles and go out of their way to accommodate them (e.g., by moving up far enough so that following vehicles can pull out and go straight).
| Many |
All | - Oncoming vehicles behind the turning vehicle are a source of concern and lead to extra caution in case they try to get through the intersection in conflict with the driver’s vehicle.
| Many |
Congestion |
All | - Congestion prompts drivers to go through the light to avoid waiting through another light cycle.
| Some |
Pedestrians and Bicyclists |
All | - They always check crosswalks.
| Many |
Older | - They also watch for skateboarders, roller bladers, and scooters.
| Some |
Older and middle-aged | - They are concerned about pedestrians and bicyclists not following the rules, and being difficult to see at night.
| Few |
Night Driving |
All | - Reduced visibility causes them to be more cautious and willing to wait longer to be sure that it is safe to go through the light.
| Many |
All | - They are more careful because of the increased number of drunk drivers on the road during this time.
| Some |
All | - Night driving also has benefits because oncoming vehicle headlamps can be seen from farther away.
| Some |
Glare |
Older | - Glare from oncoming lights at night makes them more cautious.
| Some |
Younger | - Glare from oncoming lights reduces their ability to judge the speed of the oncoming traffic, sometimes making vehicles appear closer or further away than they actually are.
| Some |
All | - Having the sun in their eyes causes them to be more conservative in their gap judgments.
| Some |
Terrain |
Seattle | - Being on a hill would prompt them to wait for the light to turn red because they are less visible to oncoming traffic.
| Some |
Low—Traction Conditions |
All | - They are more cautious in the rain, ice, and snow because oncoming traffic would have a harder time stopping.
| Many |
Young males in Washington, DC | - They do not think that weather is a factor unless it impacts visibility.
| Most |
Vehicle Type |
All | - Turning in this scenario depends on the type vehicle that both you and the oncoming driver are driving.
| Many |
All | - Drivers of small cars have greater difficulty seeing the roadway (especially if the oncoming vehicle is a large SUV) and therefore have to be more cautious.
| Some |
All | - Driving powerful cars with quick acceleration would make them more likely to accept smaller gap sizes.
| Some |
All | - Drivers of large vehicles find this situation easier to deal with because they have a better view of the roadway.
| Some |
Scenario 3: Turning Left onto a Major Road with Moderate Traffic
A vehicle is stopped on a minor road with a stop sign, waiting to turn left onto a major road (that has no stop sign); a consistent flow of vehicles going at high speeds is crossing in both directions on the major road.
Table 35. What are drivers most likely to do in this situation (scenario 3)?
Group | Action | Strength |
All |
| More than half |
All, especially older and young females |
- Abandon the left turn and make a right turn instead, followed by the necessary adjustments to get back on course.
| Less than half |
Table 36. What steps do drivers take in completing the action (scenario 3)?
Group | Action | Strength |
Viewing Traffic |
All | - They check for pedestrians and creep forward slightly to get a better view.
| Almost all |
All | - They do not go any further than the crosswalk until they had a chance to assess the situation and get a sense of the speed and timing of the traffic.
| Many |
Gap Judgment |
All | - They alternate between looking in both directions, starting with the right-going direction.
| Most |
All | - They look at right-going traffic exclusively until there is a safe gap then look towards left-going traffic.
| Few |
Strategies for Turning |
All | - If there is a gap on the left but none on the right, they pull out after the first right-going car goes by and wait in the inside right-going lane until there is a sufficient gap in left-going traffic.
| Almost half |
All | - They pull out into the outside right-going lane so that other cars would have to let them in.
| Some |
All | - They wait until there are sufficient gaps in both directions.
| Almost half |
All | - They wait (or hope) for a nearby traffic light to stop traffic in either direction so that they could have a larger gap.
| Some |
Making the Turn |
All | - They go into the outside left-going lane to avoid the car in the inside left-going lane coming up behind them too quickly.
| About half |
All | - They wait until they are certain that they could at least get in "clear" past the inside left-going vehicle.
| About half |
All | - They go into the inside left-going lane and then quickly signal and get over into the outside lane.
| Some |
All | - They accelerate as quickly as possible to get up to speed with the car in the inside left-going lane.
| Some |
Table 37. What is the decisionmaking process (scenario 3)?
Group | Action | Strength |
Information-Gathering Strategies |
All | - They alternately look back and forth and judge gaps in both directions, starting with vehicles in the right-going outside lane then the left-going inside lane, spending about equal time on each direction.
| Most |
All | - They look exclusively at right-going traffic until there is a safe gap, and then look at left-going traffic for a safe gap, and also double-check the gap in right-going traffic before going.
| Some |
All | - They split up the task by going into the middle of the roadway as an interim step, which allows them to focus on only one direction at a time.
| Some |
All | - They focus on the car in the inside left–going lane, once they determine that the gaps in both directions are sufficient.
| Most |
All | - They also focus on the car in the outside left–going lane, either because they want to get out of the way of the left-going inside vehicle or to turn directly into that lane.
| Some |
Decisionmaking |
All, but especially young males | - They make a "gut" decision to turn, based on experience and by factoring in speed and distance conditions, in addition to their car’s ability to accelerate.
| Some |
All | - They become less patient as time passes and are more likely to make rash decisions.
| Some |
All, but especially young males | - They think through the decision to turn and are very cautious, factoring in speed and distance conditions, in addition to their car’s ability to accelerate.
| Some |
All | - They assume that other vehicles will slow down to avoid conflicts, but they also often looked for confirmation of that assumption before acting.
| Some |
All | - They are concerned that crossing traffic might change lanes.
| Few |
Table 38. How do drivers decide (what steps are involved) whether or not a gap in traffic is sufficient? What factors are relevant (e.g., speeds, distance to cross, weather) (scenario 3)?
Group | Factor | Strength |
All |
- They identify a safe gap based on speed and distance.
| Many |
All |
- They instinctively know how fast cars typically go, and based on that, they wait for a gap that they feel they can make it into.
| Many |
Middle–aged |
- They look beyond the nearest vehicles for safe gaps farther down the road.
| One |
All |
- They look for larger gaps in left–going traffic because it takes them longer to get there.
| Some |
All |
- Visibility factors, nighttime, glare, and hills affect gap judgments.
| Many |
All |
- Being impatient makes them more likely to make bad judgments about acceptable gap size and the distance of approaching cars.
| About 1/5 |
Table 39. What size gaps are drivers comfortable with (scenario 3)?
Group | Size | Strength |
All |
| Few |
All |
| Few |
All |
- Somewhere between one-car length and no vehicles in sight.
| Most |
Young males |
- They are generally willing to accept smaller gaps than other drivers.
| Many |
Table 40. What external factors make the task of deciding when to turn more complicated/difficult or more demanding (scenario 3)?
Group | Factors | Strength |
All |
- The presence of additional lanes in each direction because drivers have to watch for cars changing lanes.
| Many |
All |
- Obstructions along the curb make it harder to see (e.g., parked cars or vans, buses, buildings, shrubbery), and sometimes force them to inch out further than they are comfortable with.
| Many |
Table 41. Complicating factors (scenario 3).
Group | Factor | Strength |
Other Vehicles |
All | - The presence of other drivers behind them is not a significant factor in this scenario.
| Many |
Congestion |
All | - They are willing to wait a relatively long time for a safe gap.
| Many |
All | - The longer they wait, and the more impatient they become, the more likely they are to make bad judgments about the acceptable size of gaps and the distance of approaching cars.
| About 1/5 |
Pedestrians and Bicyclists |
All | - They are more concerned about pedestrians and bicyclists in the crosswalk that they would be turning into than the one right in front of them because drivers feel that it is easy to see them there.
| Most |
Night Driving |
All | - They have mixed views about the impacts of nighttime because, while it makes it harder to judge the gap, it is also easier to see oncoming cars from far away.
| Most |
All | - They feel that twilight is the worst time because other cars are hard to see and they do not often put on their lights.
| Many |
Glare |
All | - They will wait longer due to headlight glare in the country but not in the city, where glare is not as bad.
| Many |
All | - If glare from the sun is bad they might not make the turn at all.
| Some |
Low-Traction Conditions |
All | - They are concerned about slippery conditions, including whether oncoming traffic will be able to stop or slow down.
| Many |
All | - They are concerned about having problems accelerating, skidding, or "fishtailing" if they make the turn too quickly.
| Some |
Scenario 4: Rear-End Crashes
Approaching an intersection at speed, the car in front stops suddenly when the light changes to yellow; the driver needs to slam on the brakes to avoid a rear-end collision.
Table 42. How many drivers have been involved as the following vehicle in a rear-end crash or had a near-miss at an intersection (scenario 4)?
Group | Number | Strength |
All |
- They have been involved in crashes or near-misses as both the lead vehicle and the following vehicle.
| More than 1/6 |
All |
- They have been involved in a near-miss as either the lead vehicle or the following vehicle.
| More than 1/3 |
It should be noted that although drivers responded with the frequencies presented above when directly asked about their involvement in rear-end crashes/near-misses, a far greater proportion of participants discussed these issues as if they had also encountered these situations.
Table 43. What were the circumstances that caused the incident to happen (scenario 4)?
Group | Circumstance | Strength |
Not Paying Attention |
All | - They admit to not paying close enough attention to the road or car ahead.
| Some |
Younger | - They have had near-misses or collisions as a result of using a cell phone or playing with the radio.
| Many |
Tailgating |
All | - They experienced crashes or near-misses when driving too close to the car in front of them.
| Some |
Making Faulty Assumptions About the Traffic Flow |
All | - They have gotten into rear-end collisions as a result of incorrect assumptions made about the traffic flow, such as that a lead vehicle will go through the intersection when it stops instead or by getting cut off by other vehicles.
| Some |
Going Too Fast |
All | - They have had rear-end collisions because they did not slow down soon enough after a lead vehicle slowed abruptly.
| Some |
Middle-aged and younger | - They have had rear-end collisions because they were late and did not sufficiently slow down as they approached the intersection.
| Some |
Table 44. How closely do respondents typically follow other vehicles? What factors determine how closely drivers follow other vehicles (scenario 4)?
Group | Response | Strength |
How Closely They Follow |
All | - Their chosen following distance is based on rules of thumb, such as the 2-second rule or other heuristics.
| Many |
Older and young females | - They generally leave "ample" room between themselves and the lead vehicle.
| Many |
Deciding Factors |
All | - The distance at which they follow other vehicles depends on the types of vehicles that they and others are driving.
| Some |
All | - They leave more space when driving an SUV or other vehicle that stops more slowly.
| Some |
Young males | - They leave more space when driving a new car.
| Few |
All | - The fact that they will be liable if they rear-end the lead vehicle prompts them to leave more space.
| Many |
Table 45. What are some strategies for avoiding rear-end conflict situations (scenario 4)?
Group | Action | Strength |
As Following Vehicle |
All | - They hit their brakes as soon as they see any break lights go on in front of them.
| Most |
All | - They look to see if there are other reasons why the lead car is slowing or stopping (such as the presence of pedestrians or a hazard on the road).
| Few |
All | - They try to anticipate the situation using a variety of different methods.
| Many |
All | - They leave more stopping distance in the front of them.
| Some |
All, but especially older | - They slow down as they approach the intersection.
| Some |
As Lead Vehicle |
All | - They look in the rearview mirror at the following car more frequently.
| Most |
All | - They pump their brakes ahead of time to warn other drivers that they will be stopping soon.
| Some |
Table 46. How do drivers detect or anticipate when the lead vehicle will slow or stop (scenario 4)?
Group | Action | Strength |
All |
- They prepare to stop when the light changes and start watching the lead vehicle to see whether it will slow down or speed up to get through the light.
| Most |
All |
- They detect that the car in front of them is stopping because the brake lights capture their attention.
| Almost all |
Younger |
- They sometimes delay their decision to stop (although they will slow down) until they determine whether or not the lead vehicle is going through the intersection.
| Many |
All |
- They use various strategies to anticipate the light change and become more alert or prepare to stop before it does.
| Some |
Table 47. What are drivers likely to do in response to this situation (scenario 4)?
Group | Action | Strength |
All |
- They would get into the inside or another lane if possible.
| Many |
All |
- They would go up onto the curb or shoulder if they could not stop on time.
| Many |
All |
- They would already be slowing down as they approached the intersection and would likely be able to stop in time.
| Some |
All |
- They would look behind them to see if they might get rearended if they stop too suddenly.
| About a quarter |
Table 48. Complicating factors (scenario 4).
Group | Factor | Strength |
Lead Vehicle |
All | - They try to gauge how the driver in front of them drives as they go along and try to anticipate how they might behave based on the driver’s age and vehicle type.
| Some |
Younger | - They leave more room if the lead driver appears likely to stop.
| Some |
All | - They assume that heavier vehicles are likely to go through the light.
| Few |
Congestion |
All | - Congestion makes them tailgate more closely during rush hour.
| Some |
Poor Visibility |
All | - They do not think that this is a factor because the situation requires attention to their immediate surroundings, which would not be affected by poor visibility.
| Some |
Glare |
All | - They leave more space in front of them if glare from the sun makes it hard to see.
| Few |
Low-Traction Conditions |
All | - Slippery conditions are not a big factor because they do not think that they have any choice but to try to stop suddenly in this scenario.
| Some |
All | - They leave more space between themselves and the car in front of them when it was raining.
| Few |
Terrain |
All | - They anticipate that it is more difficult to stop while going downhill and start breaking sooner.
| Some |
COUNTERMEASURES
The following issues were addressed for each countermeasure:
- Would implementing this countermeasure improve safety?
- What are some of the implementation issues?
- What are the advantages and disadvantages of the countermeasure?
Countermeasure 1.1: Red-Light Camera
Table 49. Would implementing this countermeasure improve safety (countermeasure 1.1)?
Group | Opinion | Strength |
Washington, DC, and Chicago, IL, older |
- They are strongly opposed to red-light cameras and do not feel that they improve safety.
| Almost all |
Seattle, WA, older |
- They think that it is a great safety improvement.
| Almost all |
Washington, DC, and Chicago, IL, young males |
- They think that red-light cameras work and improve safety, based on their direct experience with them or from what they hear or read about them.
| Almost all |
Seattle, WA, young males |
- They are more reluctant to admit that they would improve safety and they did not trust them.
| Most |
Middle-aged and young females |
- They are in favor of the cameras and feel that they help create safer situations since they had changed their own behavior in response to the cameras.
| About half |
Table 50. What are some of the implementation issues (countermeasure 1.1)?
Group | Issue | Strength |
All |
- For cameras to be effective, drivers would need to be educated about them by either posting signs where they are located or through public service announcement campaigns.
| Many |
All |
- Cameras should only be placed at dangerous intersections or places where many people run red lights.
| Some |
All |
- Cameras would be ineffective with habitual red-light runners or drunk drivers because these drivers blatantly disregard the law and would probably disregard the cameras as well.
| Many |
All |
- They have mixed views on the effectiveness of periodically changing the camera locations.
| Many |
All |
- Cameras might be susceptible to vandalism if they are positioned within reach of the ground.
| Few |
Table 51. What are some of the advantages and disadvantages (countermeasure 1.1)?
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
All | - Cameras would free up police officers for other activities.
| Some |
Disadvantages |
All | - They do not trust cameras to work properly or as described (that they only take a picture of a driver entering the intersection after the light has turned red).
| Most |
All | - Drivers believe that the yellow-phase duration is timed for maximizing revenue, not safety or traffic flow.
| Many |
All | - Cameras give the impression that "big brother" is watching you.
| Many |
All | - If they are wrongly accused, they would be unable to contest it because the photo provides indisputable evidence.
| Some |
Older | - Younger respondents would benefit and learn more from the effect of being pulled over by actual police officers versus just getting a ticket in the mail.
| Many |
All | - Cameras could cause more rear-end collisions because people might slam on their brakes if they saw a camera or a flash.
| Many |
All | - Cameras could slow traffic flow.
| Some |
All | - There is a possibility of wrongfully getting a ticket if someone else is driving your car.
| Some |
Table 52. What would it take to make red-light cameras acceptable (countermeasure 1.1)?
Group | Issue | Strength |
All |
- Fairness is critical—those turning left in the middle of intersections when the light turns red and those making right turns on a red should not get tickets.
| Many |
All |
- Cameras are fine if their goal is to improve safety, but not to raise money, which is what they believe is currently the primary purpose of cameras.
| Some |
All |
- A "three strikes, and you’re out program" for drivers that are unfamiliar with the cameras.
| Some |
All |
- It would be helpful if the camera picture could identify the driver so that the vehicle owners could determine if the ticket was the result of someone else driving their vehicle.
| Some |
All |
- There should be a way to contest the ticket because of extenuating circumstances (e.g., slippery roads), which are not adequately captured in the camera picture.
| Few |
All |
- Cameras would be more acceptable in high-priority locations such as intersections near schools.
| Few |
Countermeasure 1.2: High-Visibility Traffic Lights
Table 53. Would implementing this countermeasure improve safety (countermeasure 1.2)?
Group | Opinion | Strength |
Older |
- It would be a welcome help to these drivers in addition to being effective for improving safety in general.
| Most |
Young males |
- It would not help since lack of conspicuity was not the reason they go through red lights.
| Most |
Middle-aged and young females |
| About half |
Middle-aged and young females |
- It would not apply to them.
| About half |
Table 54. What are some of the implementation issues (countermeasure 1.2)?
Group | Issue | Strength |
All |
- This would work best in suburban or rural areas because it might otherwise get lost in all of the other downtown lights.
| Many |
All |
- It might help in the midst of the other downtown lights.
| Few |
All |
- This would be good at high-crash intersections, but not at all intersections.
| Some |
All |
- This might not be useful when the light was blocked by an SUV or a big truck; increasing the overall number of traffic lights (e.g., in different positions) might be more effective.
| Some |
All |
- There is some concern about the visibility of the yellow light next to the bright yellow background.
| Some |
Table 55. What are some of the advantages and disadvantages (countermeasure 1.2)?
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
Disadvantages |
Middle-aged and young males | - The double red might be confusing and seemed expensive.
| Some |
Countermeasure 1.3: Advance Traffic Light Warning Signs
Table 56. Would implementing this countermeasure improve safety (countermeasure 1.3)?
Group | Opinion | Strength |
Middle-aged and younger |
- It would be effective overall.
| About 1/3 |
Older |
- It would be helpful and improve safety in most situations, especially in high-speed areas.
| Almost all |
Middle-aged and younger |
- It would not be effective because of lack of trust in the accuracy of the warning’s timing.
| Some |
Table 57. What are some of the implementation issues (countermeasure 1.3)?
Group | Issue | Strength |
Middle-aged and younger |
- Drivers do not trust the sign to accurately take into account their actual travel speeds.
| Some |
Middle-aged and younger |
- Drivers might not see it or might confuse it with other signage (e.g., construction signs).
| Some |
Middle-aged and younger |
- Drivers might ignore the sign once they get used to it.
| Some |
All |
- It would be more effective in rural and suburban areas or on roads where the speed limit is above 56 km/h (35 mi/h).
| Almost all |
All |
- It would be helpful in areas of low visibility, on curves and hills, and in fog or other bad weather.
| Some |
Table 58. Advantages and disadvantages (countermeasure 1.3).
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
Disadvantages |
Young males | - Some drivers might actually speed up in response to the warning if they felt they were close enough to go through the intersection before the light changed.
| Some |
All | - It might give drivers a false sense of security, be distracting/confusing, or be hard to see by the side of the road.
| Few |
Countermeasure 1.4: Intersection Collision-Warning Systems
Table 59. Would implementing this countermeasure improve safety (countermeasure 1.4)?
Group | Opinion | Strength |
Washington, DC |
- They think it would work.
| About 3/4 |
Chicago, IL, and Seattle, WA |
- They are receptive to the basic idea.
| About half |
All |
- They think that drivers would definitely stop if they saw this.
| Many |
Table 60. What are some of the implementation issues (countermeasure 1.4)?
Group | Issue | Strength |
All |
- It has potential in a different form but is "too much" in its current implementation.
| Some |
All |
- Having fewer lights or eliminating the lights embedded in the pavement would be an improvement.
| Many |
All |
- Placing the warning lights before intersections, adding sounds, or using yellow lights might make it more effective.
| Some |
All |
- It would require a big campaign to let everyone know what it is and what drivers should do when they see it.
| Some |
All |
- There would be skepticism over whether the technology actually works and if it would provide an early enough warning to stop in time.
| Some |
All |
- It might be confusing to drivers and they may not know what to do.
| Some |
Table 61. Advantages and disadvantages (countermeasure 1.4).
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
Disadvantages |
All | - The signals and flashing lights might "freak out" certain drivers and actually cause more crashes if they stopped short.
| Many |
All | - They are concerned that so much taxpayer money would be spent addressing the actions of irresponsible drivers and lawbreakers—even if it was to protect others.
| Many |
All | - This solves the wrong problem and does not address the drivers that would go through the light.
| Few |
All | - It might make some drivers lazy and more likely to depend on these to look out for them.
| Some |
Table 62. How does this system compare to an in-vehicle warning system (countermeasure 1.4)?
Group | Issue | Strength |
All |
- Drivers are less receptive to the idea of having the warning system in their automobiles.
| Most |
All |
- Unlike seatbelts, this countermeasure would not be useful unless everybody has one.
| Most |
All |
- This system would have the same impact in terms of startling some drivers, but at least with the infrastructure-based system, drivers would have a clear indication of why the lights are flashing.
| Most |
All |
- It would increase the costs of their car.
| Few |
All |
- It would be less effective because it might not warn the redlight runner, as is the case with the intersection-based system.
| Few |
Older |
- There should be sound in addition to lights.
| Few |
Countermeasure 2.1: Protected left-turn lights
Table 63. Would implementing this countermeasure improve safety (countermeasure 2.1)?
Group | Opinion | Strength |
All |
- These are very effective at improving safety, and drivers would like to see them at all busy intersections.
| Almost All |
Table 64. What are some of the implementation issues (countermeasure 2.1)?
Group | Issue | Strength |
All |
- They sometimes have problems if the traffic signal has both a green light and a green arrow at the same time.
| Few |
All |
- The light could be improved by including a sensor that only activates the turn arrow when someone is in the turning lane.
| Few |
All |
- Stopping pedestrians from crossing when drivers had the green arrow would be an improvement.
| Few |
Countermeasure 3.1: Automatic gap detection
Table 65. Would implementing this countermeasure improve safety (countermeasure 3.1)?
Group | Opinion | Strength |
All |
- This is a good idea and would improve safety.
| About 1/3 |
Chicago, IL, young females |
- It would be helpful and it makes sense.
| Almost all |
All |
- Drivers are concerned about how trustworthy the system is and would prefer to judge gap safety "with their own eyes."
| Many |
All |
- They would prefer other countermeasures, such as traffic light, traffic island, or "suicide" lane.
| Some |
Table 66. What are some of the implementation issues (countermeasure 3.1)?
Group | Issue | Strength |
All |
- This approach would be most effective if it only addressed the oncoming traffic from the right and would be confusing if it addressed both directions.
| About half |
All |
- They are concerned that the timing would not work.
| Many |
All |
- They are uncertain if it takes into account different weather conditions and how fast their car can accelerate.
| Some |
All |
- The system should be designed to accommodate the lowest common denominator.
| Some |
All |
- The warning should be accompanied by a continuous or contingent blinking light indicator on the crossing road so that oncoming traffic would be notified that someone might be turning in front of them.
| Few |
All |
- The warning signal should blink when it is safe to turn instead of when it is unsafe.
| Few |
All |
- The sign would be too difficult to read because the text is too small or too verbose.
| Few |
All |
- The flashing yellow is confusing, and drivers might not understand it.
| Some |
Table 67. What are some of the advantages and disadvantages (countermeasure 3.1)?
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
Disadvantages |
All | - Drivers might get lazy or dependent upon the sign and not check the actual gap properly.
| Some |
All | - There is no need for it, or drivers are likely to ignore it in favor of their own judgments.
| Some |
Table 68. Gap advisory system (countermeasure 3.1).
Group | Issue | Strength |
Washington, DC |
- They are receptive to the idea and think that it would be helpful.
| Many |
Chicago, IL, and Seattle |
- They think that it would not help or make a difference to drivers.
| Almost All |
Countermeasure 3.2: Synchronized Adjacent Traffic Signals
Table 69. Would implementing this countermeasure improve safety (countermeasure 3.2)?
Group | Opinion | Strength |
All |
- It is an effective approach and will improve safety at the intersection.
| About 3/4 |
All |
- It would be more effective than automated gap detection.
| Many |
Table 70. What are some of the implementation issues (countermeasure 3.2)?
Group | Issue | Strength |
All |
- It would be even better if sensors judged when it was needed so the traffic wouldn’t get needlessly backed up or stopped.
| Many |
Table 71. What are some of the advantages and disadvantages (countermeasure 3.2)?
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
Disadvantages |
All | - Drivers would still have to be aware of people turning on red lights at the adjacent intersections or coming from driveways and other side streets.
| Few |
Countermeasure 4.1: Intersection Rumble Strips
Table 72. Would implementing this countermeasure improve safety (countermeasure 4.1)?
Group | Opinion | Strength |
All |
- This is an effective countermeasure and it would improve safety.
| About half |
All |
- This is not an effective countermeasure because the potential problems outweigh the benefits (see below).
| About half |
All |
- It would help drivers refocus their attention on the road and on the intersection ahead.
| Many |
All |
- It does not address the situation because fatigue and distraction are not the primary problems.
| Some |
Table 73. What are some of the implementation issues (countermeasure 4.1)?
Group | Issue | Strength |
All |
- It would not be necessary at every intersection, but helpful at dangerous intersections.
| Many |
All |
- Drivers would get use to them, and they would lose their effectiveness if they were at every intersection.
| Most |
All |
- Rumble strips are better suited for the sides of highways and the approaches to toll booths because they are more frequently encountered in those situations.
| Some |
All |
- It might make people slow down, which they should not always do in intersections, especially when the light is green.
| Some |
All |
- It implicitly sends the message to drivers that it is acceptable to be distracted.
| Few |
Table 74. What are some of the advantages and disadvantages (countermeasure 4.1)?
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
Disadvantages |
All | - It would be very annoying because the rumble strips are loud and would rattle their cars or make them think they have a flat tire.
| Many |
All | - It will cause additional wear and tear on their cars and tires.
| Some |
Countermeasure 4.2: Improved Skid Resistance
Table 75. Would implementing this countermeasure improve safety (countermeasure 4.2)?
Group | Opinion | Strength |
All |
- It would be effective and would improve safety.
| Most |
All except Washington, DC, older |
- It is preferable to rumble strips, and it would be more effective in improving safety than rumble strips.
| Most |
All |
- A combination of intersection rumble strips and improved skid resistance would be the most effective implementation.
| Many |
Table 76. What are some of the implementation issues (countermeasure 4.2)?
Group | Issue | Strength |
All |
- It would be important that this countermeasure be consistently implemented so that drivers could tell when it is present in case they must rely on it.
| Few |
All |
- It should not be at every intersection, only at dangerous ones.
| Many |
All |
- The skid-resistant treatment would have to start back far enough so that it would be available for all the drivers that need to stop—otherwise, lead vehicles on the treatment would stop more quickly than following vehicles not on the treatment, making rear-end collisions more likely.
| Some |
Table 77. What are some of the advantages and disadvantages (countermeasure 4.2)?
Group | Issue | Strength |
Advantages |
All | - Safety is the primary advantage noted.
| Many |
All | - It would work well on snow and ice.
| Some |
Disadvantages |
All | - Drivers might come to rely on it, which might falsely shorten their perception of what their reaction time is.
| Few |
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