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Publication Number: FHWA-HRT-04-100
Date: September 2005
Safety Effects of Marked Versus Unmarked Crosswalks at Uncontrolled Locations Final Report and Recommended Guidelines
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Pedestrians are legitimate users of the transportation system, and they should, therefore, be able to use this system safely and without unreasonable delay (figure 1). Pedestrians have a right to cross roads safely, and planners and engineers have a professional responsibility to plan, design, and install safe and convenient crossing facilities. Pedestrians should be included as design users for all streets.
As a starting point, roads should be designed with the premise that there will be pedestrians, that they must be able to cross the street, and that they must be able to do it safely. The design question is, "How can this task best be accomplished?"
Providing marked crosswalks traditionally has been one measure used in an attempt to facilitate crossings. Such crosswalks commonly are used at uncontrolled locations (i.e., sites not controlled by a traffic signal or stop sign) and sometimes at midblock locations. However, there have been conflicting studies and much controversy regarding the safety effects of marked crosswalks. This study evaluated marked crosswalks at uncontrolled locations and offers guidelines for their use.
Marked crosswalks are one tool used to direct pedestrians safely across a street. When considering marked crosswalks at uncontrolled locations, the question should not be simply, "Should I provide a marked crosswalk or not?" Instead, the question should be, "Is this an appropriate tool for directing pedestrians across the street?" Regardless of whether marked crosswalks are used, there remains the fundamental obligation to get pedestrians safely across the street.
In most cases, marked crosswalks are best used in combination with other treatments (e.g., curb extensions, raised crossing islands, traffic signals, roadway narrowing, enhanced overhead lighting, traffic calming measures). Marked crosswalks should be one option in a progression of design treatments. If one treatment does not accomplish the task adequately, then move on to the next one. Failure of one particular treatment is not a license to give up and do nothing. In all cases, the final design must accomplish the goal of getting pedestrians across the road safely.
The 2000 Uniform Vehicle Code and Model Traffic Ordinance (Uniform Vehicle Code) (Section 1-112) defines a crosswalk as: (1)
Thus, a crosswalk at an intersection is defined as the extension of the sidewalk or the shoulder across the intersection, regardless of whether it is marked or not. The only way a crosswalk can exist at a midblock location is if it is marked. Most jurisdictions have crosswalk laws that make it legal for pedestrians to cross the street at any intersection, whether marked or not, unless the pedestrian crossing is specifically prohibited.
According to Section 3B.17 of the Manual on Uniform Traffic Control Devices (MUTCD), crosswalks serve the following purposes: (2)
The MUTCD also provides guidance on marked crosswalks, including:
The MUTCD further states that: "Crosswalk lines should not be used indiscriminately. An engineering study should be performed before they are installed at locations away from traffic signals or STOP signs."
However, the MUTCD does not provide specific guidance relative to the site condition (e.g., traffic volume, pedestrian volume, number of lanes, presence or type of median) where marked crosswalks should or should not be used at uncontrolled locations. Such decisions have historically been left to the judgment of State and local traffic engineers.
Furthermore, practices on where to mark or not mark crosswalks have differed widely among highway agencies, and this has been a controversial topic among researchers, traffic engineers, and pedestrian safety advocates for many years. More specific safety research and guidelines have been needed on where to mark or not mark crosswalks at uncontrolled locations.
Designated marked or unmarked crosswalks are also required to be accessible to wheelchair users if an accessible sidewalk exists. The level of connectivity between pedestrian facilities is directly related to the placement and consistency of street crossings.
There has been considerable controversy in the United States about whether marked crosswalks increase or decrease pedestrian safety at crossing locations that are not controlled by a traffic signal or stop sign. Many pedestrians consider marked crosswalks as a tool to enhance pedestrian safety and mobility. They view the markings as proof that they have a right to share the roadway, and in their opinion, the more the better. Many pedestrians do not understand the legal definition of a crosswalk and think that there is no crosswalk unless it is marked. They may also think that a driver can see the crosswalk markings as well as they can, and they assume that it will be safer to cross where drivers can see the white crosswalk lines.
When citizens request the installation of marked crosswalks, some engineers and planners still refer to the 1972 study by Herms as justification for not installing marked crosswalks at uncontrolled locations. (3) That study found an increased incidence of pedestrian collisions in marked crosswalks, compared to unmarked crosswalks, at 400 uncontrolled intersections in San Diego, CA. Questions have been asked about the validity of that study, and the study results have sometimes been misquoted or misused. Some have misinterpreted the results of that study. The study did not conclude that all marked crosswalks are unsafe, and the study also did not include school crosswalks. A few other studies have also tried to address this issue since the Herms study was completed. Some were not conclusive because of their methodology or sample size problems, while others have fueled the disagreements and confusion on this matter.
Furthermore, most of the previous crosswalk studies have analyzed the overall safety effects of marked crosswalks but did not investigate their effects for various numbers of lanes, traffic volumes, or other roadway features. Like other traffic control devices, crosswalks should not be expected to be equally effective or appropriate under all roadway conditions.
The practice of where to install crosswalks differs considerably from one jurisdiction to another across the United States, and engineers have been left with using their own judgment (sometimes influenced by political and/or public pressure) in reaching decisions. Some cities have developed their own guidelines on where marked crosswalks should or should not be installed. At a minimum, many cities tend to install marked crosswalks at signalized intersections, particularly in urban areas where there is pedestrian crossing activity. Many jurisdictions also commonly install marked crosswalks at school crossing locations (especially where adult crossing guards are used), and they are more likely to mark crosswalks at intersections controlled by a stop sign. At uncontrolled locations, some agencies rarely, if ever, choose to install marked crosswalks; other agencies install marked crosswalks at selected pedestrian crossing locations, particularly in downtown areas. Some towns and cities have also chosen to supplement selected marked crosswalks with advance overhead or post-mounted pedestrian warning signs, flashing lights, "Stop for Pedestrians in Crosswalk" signs mounted at the street centerline (or mounted along the side of the street or overhead), and/or supplemental pavement markings.
Many highway agencies routinely mark crosswalks at school crossings and signalized intersections. While questions have been raised concerning marking criteria at these sites, most of the controversy on whether to mark crosswalks has pertained to the many uncontrolled locations in U.S. towns and cities. The purpose of this study was to determine whether marked crosswalks at uncontrolled locations are safer than unmarked crosswalks under various traffic and roadway conditions. Another objective was to provide recommendations on how to provide safer crossings for pedestrians. This includes providing assistance to engineers and planners when making decisions on:
The results of this study should not be misused as justification to do nothing to help pedestrians cross streets safely. Instead, pedestrian crossing problems and needs should be identified routinely, and appropriate solutions should be selected to improve pedestrian safety and access. Deciding where to mark or not mark crosswalks is only one consideration in meeting that objective.
This final report is based on a major study for the Federal Highway Administration (FHWA) on the safety effects of pedestrian facilities. The report titled, "Safety Effects of Marked versus Unmarked Crosswalks at Uncontrolled Locations: Executive Summary and Recommended Guidelines" also was prepared as a companion document. (4)
Studies of the effects of marked crosswalks have yielded contradictory results. Some studies reported an association of marked crosswalks with an increase in pedestrian crashes. Other studies did not show an elevated collision level associated with marked crosswalks, but instead showed favorable changes. As to the negative findings, assertions were made that marked crosswalks somehow induced incautious behavior on the part of pedestrians, triggered perhaps by what they thought the markings signified. The following paragraphs describe the findings of some of these studies.
An early and oft-quoted study in California performed by Herms investigated pedestrian crash risk at marked and unmarked crosswalks. (3) This study evaluated pedestrian crashes at 400 intersections where at least 1 crosswalk was painted and another was not. There are thousands of other intersections in San Diego, CA, where neither crosswalk was painted or both were painted, but those were not included in the Herms study. That study rightly emphasizes the difficulty of "maintaining equivalent conditions" in comparing marked and unmarked crosswalks, and lists 12 factors to try to address such difficulties. Since the study was confined to intersections that had one marked and one unmarked crosswalk across the same main thoroughfare, it is not surprising that the vehicle traffic exposure was quite similar between the marked and unmarked crosswalks. However, pedestrian volume was three times as high on the marked crosswalks as on the unmarked crosswalks. Herms stated:
The Herms study, however, does not say what evidence the author had in mind regarding incautious pedestrian behavior. No behavioral data was presented. Other authors have advanced similar assertions with regard to pedestrian behavior in marked crosswalks.
One of the issues involved in this crosswalk controversy relates to questions on the warrants used in San Diego, CA, to determine where to paint crosswalks. Specifically, the warrant directive for San Diego (January 15, 1962), established a point system calling for painting crosswalks when: (1) traffic gaps were fewer rather than more numerous; (2) pedestrian volume was high; (3) speed was moderate (not low, not high); and (4) other prevailing factors were present, such as previous crashes. Thus, it is possible that crosswalks may have been more likely to be painted in San Diego, CA, where the conditions were most ripe for pedestrian collisions (compared to sites which were unmarked). This could at least partly explain the increase in pedestrian crashes at marked crosswalks in the Herms study. Furthermore, the city of San Diego did not eliminate the use of marked crosswalks at uncontrolled locations based on the results of this study. The study recommended against the indiscriminate use of markings at uncontrolled locations. It should be mentioned that the Herms study did not distinguish whether the results would have differed, for example, for two-lane versus multilane roads, or for low-volume versus high-volume roads.
Gibby et al. later revisited the issue. (5) Their report contains a thorough review of the literature and also includes an analysis of pedestrian crashes at 380 highway intersections in California. These intersections were picked after a detailed, multistep selection process in which more than 10,000 intersections were initially considered, and all but 380 were excluded. Their results showed
that pedestrian crash rates at these 380 unsignalized intersections were 2 or 3 times higher in marked than in unmarked crosswalks when expressed as crash rates per unit pedestrian-vehicle volume. This study had the advantage of including a relatively large sample of intersections in cities throughout California, which may have minimized any data bias resulting from crosswalk marking criteria. However, it should be mentioned that, as with the Herms study, the Gibby study also did not determine how the results (between marked and unmarked crosswalks) might have differed for two-lane versus multilane roads, and/or for roads with low average daily traffic (ADT) compared to high ADT.
Other studies have been conducted to address this issue. Gurnett described a project to remove painted stripes from some crosswalks following a bad crash experience. (6) This was a before-after study of three locations that were selected for crosswalk removal because they had a recent bad crash record. After removing the crosswalks, crashes decreased. Such results do not show the effect of removing the paint, but are very likely the result of the well-known statistical phenomenon of regression to the mean. It is also not clear whether pedestrian crossing volumes may have dropped after the marked crosswalks were removed. (6)
Another study of marked crosswalks at unsignalized intersections was reported by the Los Angeles, CA, County Road Department in July 1967. (7) The county reported results of a before-after study of 89 intersections. Painted crosswalks were added at each site, but the basis for selecting those sites was not mentioned. Pedestrian crashes increased from 4 during the before period to 15 in the after period. The before-after design in this study is preferable to a treatment-control model in this instance, and better takes the selection effect into account. All sites that showed crash increases were intersections with an ADT rate above 10,900. Thus, at sites with a lower ADT rate, no change in pedestrian crashes was seen. Also, rear-end collisions increased from 31 to 58 after marked crosswalks were added. The report stated that rear-end collisions increased as traffic volume increased. Nevertheless, the study showed more pedestrian crashes after painting the crosswalks than before for the sites with ADT rates above 10,500. The study could have been enhanced by including an analysis of crashes within a comparison group of unpainted sites during the same time period. It is not clear whether pedestrian volumes may have increased at the crosswalks after they were marked. (7)
In contrast to the studies described above, Tobey et al. reported reduced crashes associated with marked crosswalks. (8) They examined crashes at marked and unmarked crosswalks as a function of pedestrian volume (P) multiplied by vehicle volume (V). When the P times V product was used as a denominator, crashes at unmarked crosswalks were found to be considerably overrepresented; crashes at marked crosswalks were underrepresented considerably. Communication with the authors indicates that this study included controlled (signalized) as well as uncontrolled crossings. It seems likely, therefore, that more marked crosswalks than unmarked crosswalks were present at controlled crossings, which could at least partially explain the different results compared to other studies. The study methodology was quite useful for determining pedestrian crash risk for a variety of human and locational features. However, the study results were not intended to be used for quantifying the specific safety effects of marked versus unmarked crosswalks for various traffic and roadway situations. (8)
In 1996, Ekman conducted an analysis of pedestrian crashes at zebra crossings compared to crossings with traffic signals and also to crossings with no facilities. (9) Zebra crossings in Sweden (figure 2) consist of high-visibility crosswalk markings on the roadway, accompanied by zebra crossing signs (figure 3). The study included 6 years of collected pedestrian crash data from crossings in five cities in southern Sweden along with pedestrian counts, traffic volume, and other information for each of the three types of pedestrian crossings.
The rate of pedestrian crashes was found to be higher (approximately twice as high) at intersections which had zebra crossings, compared to locations that were signalized or had no facilities. Further, pedestrians age 60 and above were most at risk, followed by pedestrians below age 16 (see figure 4). The author also controlled for motor vehicle traffic and found similar results. (9)
Figure 4. Pedestrian crash rates for the three crossing types by age group.
In a 1999 study involving the relationship between crashes or conflicts and exposure, Ekman and Hyden compared intersections with and without zebra crossings on major streets in the cities of Malmö and Lund, Sweden. Among other conclusions, the study found that "Zebra crossings seem to have higher crash rate than approaches without zebra," and "The increased crash rate for approaches with zebra crossings is only valid on locations where the car flow is larger than 10 cars per hour." Conflict rates were about twice as high with zebra crossings compared to crossings with no control. The authors reported that the dataset did not include enough sites with car exposure greater than 250 cars per hour. The study also found that the positive effects of pedestrian refuge islands "seem to be stronger than the negative effect of zebra crossing, at least in the lower region of car exposure." This finding supports the safety benefit of having a raised pedestrian refuge island at pedestrian crossings. (10)
Yagar reported the results of introducing marked crosswalks at 13 Toronto, Canada intersections. (11) The basis for selecting the particular intersections was not described. A before-after study was conducted, and it was found that crashes had been increasing during the before period and continued to increase after crosswalks were installed. It is not apparent from the graphs that there was any change in slope associated with the time of painting the crosswalks; it would appear that marking the crosswalks did not have much of an effect on crashes. However, the author points to an increase in tailgating crashes at the intersections after crosswalk painting. He also reports that the increased crashes during the after phase seemed to be entirely explained by an increase in crashes involving out-of-town drivers. Perhaps the increase in crashes by out-of-town motorists was because they were not expecting any change in pedestrian or motorist behavior of the local residents, who may have been more familiar with the new markings. However, no behavioral data was included in the study.
In summary, there are no clear-cut results from the studies reviewed to permit concluding with confidence that either marked or unmarked crosswalks are safer. The selection bias (on where crosswalks are marked) could certainly affect the results of a given study. Units of pedestrian crash experience were also inconsistent from one study to another. Another important question relates to whether analyzing sites separately by site type (e.g., two-lane versus multilane road, high volume versus low volume) would produce different results on the safety effects of marked versus unmarked crosswalks.
In addition to crash-based studies, it is also important to review studies that evaluate the effects of crosswalk marking on pedestrian and motorist behavior. Such review can reveal changes in behavior, which can lead to crashes for different crosswalk conditions. The following paragraphs discuss some of these behavioral studies.
Katz et al. conducted an experimental study of driver and pedestrian interaction when the pedestrian crossed a street. (12) The pedestrians in question were members of the study team, and they crossed a street under a variety of conditions (960 trials). It was found that drivers stop for pedestrians as a function of several variables. Drivers stop more frequently when the vehicle's approach speed is low, when the pedestrian is in a marked crosswalk, when the distance between vehicle and pedestrian is greater rather than less, when pedestrians are in groups, and when the pedestrian does not make eye contact with the driver. Thus, the marked crosswalk is a specific factor in positive driver behavior in this study.
A study by Knoblauch et al. was conducted to determine the effect of crosswalk markings on driver and pedestrian behavior at unsignalized intersections. (13) A before-after evaluation of crosswalk markings was conducted at 11 locations in 4 U.S. cities. The observed behaviors included pedestrian crossing location, vehicle speed, driver yielding, and pedestrian crossing behavior. It was found that drivers approach a pedestrian in a crosswalk somewhat more slowly, and that crosswalk usage increases, after markings are installed. No evidence was found indicating that pedestrians are less vigilant in a marked crosswalk. No changes were found in driver yielding or pedestrian assertiveness as a result of adding the marked crosswalk. Marking pedestrian crosswalks at relatively low-speed, low-volume, unsignalized intersections was not found to have any measurable negative effect on pedestrian or motorist behavior at the selected sites (which were all two- or three-lane roads with speed limits of 56 or 64 kilometers per hour (km/h) or 35 or 40 miles per hour (mi/h)).
In a comparison study to the one discussed above, Knoblauch and Raymond conducted a before-after evaluation of pedestrian crosswalk markings in Maryland, Virginia, and Arizona. (14) Six sites that had been recently resurfaced were selected. All sites were at uncontrolled intersections with a speed limit of 56 km/h (35 mi/h). The before data were collected after the centerline and edgeline delineations were installed but before the crosswalk was installed. The after data were collected after the crosswalk markings were installed. Speed data were collected under three conditions: no pedestrian present, pedestrian looking, and pedestrian not looking. All pedestrian conditions involved a staged pedestrian. The results indicate a slight reduction in vehicle speed at most, but not all, of the sites. Overall, there was a significant reduction in speed under both the no pedestrian and the pedestrian not looking conditions. (Note: This study and the 2001 behavioral study by Knoblauch et al. mentioned above were both conducted as part of the larger FHWA study conducted in conjunction with the current study described here.)
These studies found pedestrian behavior to be, if anything, slightly better in the presence of marked crosswalks compared to unmarked crosswalks. Certainly the results showed no indication of an increase in reckless or incautious pedestrian behavior associated with marked crosswalks. All of the sites used in the Knoblauch studies were two-lane and three-lane roads, and all had speed limits of 56 or 64 km/h (35 or 40 mi/h). No formal behavioral studies were found which have studied pedestrian and motorist behaviors and conflicts on roads with four or more lanes with and without marked crosswalks. Such multilane situations may pose different types of risks for pedestrians, particularly where high traffic volume exists and/or where vehicle speeds are high.
Finally, Van Houten studied factors that might cause motorists to yield for pedestrians in marked crosswalks. (15) He measured several behaviors at intersections in Dartmouth, Nova Scotia, where interventions were introduced sequentially to increase the "vividness" of crosswalks. Researchers added signs, then a stop line, and then amber lights activated by pedestrians and displayed to motorists. The percentage of vehicles stopping when they should increased by up to 50 percent. Conflicts dropped from 50 percent to about 10 percent at one intersection, and from 50 percent to about 25 percent at another. The number of motorists who yielded increased from about 25 percent to 40 percent at one intersection, and from about 35 percent to about 45 percent at another. (15)
The preceding discussion of the literature has dealt primarily with the safety and behavioral effects of marked versus unmarked crosswalks at uncontrolled intersections. Of course, a wide variety of supplemental measures have been used with or without marked crosswalks at pedestrian crossing locations in the United States. Examples of these treatments include:
Numerous research studies have been conducted in the United States and abroad in recent years to evaluate such treatments and/or to summarize research results. Some of these include:
In addition to these research summaries, several other documents, which describe a wide range of pedestrian and traffic calming measures, include:
The study described in this report was primarily intended to compare the safety effects of marked versus unmarked crosswalks at uncontrolled locations. It did not focus on evaluating various signs, traffic calming, or other measures and devices. Instead, several companion studies were conducted as part of the larger FHWA effort, which presents evaluation results of innovative devices. These research reports may be found atwww.walkinginfo.org/rd/devices.htm.
Keywords: Marked crosswalk, Safety, Pedestrian crashes