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• Safety Effects of Marked Versus Unmarked Crosswalks at Uncontrolled Locations Final Report and Recommended Guidelines

Safety Effects of Marked Versus Unmarked Crosswalks at Uncontrolled Locations Final Report and Recommended Guidelines

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CHAPTER 3. STUDY RESULTS

SIGNIFICANT VARIABLES

Poisson and negative binomial regression models were fit to pedestrian crash data from marked and unmarked crosswalks. These analyses showed that several factors in addition to crosswalk markings were associated with pedestrian crashes. Traffic and roadway factors found to be related to a greater frequency of pedestrian crashes included higher pedestrian volumes, higher traffic ADT, and a greater number of lanes (i.e., multilane roads with three or more lanes had higher pedestrian crash rates than two-lane roads). For this study, a center two-way left-turn lane was considered to be a travel lane and not a median.

Surprisingly, after controlling for other factors (e.g., pedestrian volume, traffic volume, number of lanes, median type), speed limit was not significantly related to pedestrian crash frequency. Certainly, one would expect that higher vehicle speed would be associated with an increased probability of a pedestrian crash (all else being equal). However, the lack of association between speed limit and pedestrian crashes found in this analysis may be due to the fact that there was not much variation in the range of vehicle speed or speed limit at the study sites (i.e., 93 percent of the study sites had speed limits of 40.2 to 56.3 km/h (25 to 35 mi/h). Another possible explanation, as hypothesized by Garder, is that pedestrians may be more careful when crossing streets with higher speed limits; that is, they may avoid short gaps on high-speed roads, which may minimize the effect of vehicle speed on pedestrian crash rates. ⁽³⁰⁾ In terms of speed and crash severity, the analysis showed that speed limits of 56.3 km/h (35 mi/h) and greater were associated with a higher percentage of fatal and type A (serious or incapacitating) injuries (43 percent) compared to sites having lower speed limits (23 percent of the crashes resulting in fatal or type A injuries).

The presence of a raised median or raised crossing island was associated with a significantly lower pedestrian crash rate at multilane sites with both marked and unmarked crosswalks. These results were in basic agreement with a major study by Bowman and Vecellio ⁽³¹⁾ and also a study by Garder ⁽³²⁾ that found safety benefits for pedestrians due to raised medians and refuge islands, respectively. Furthermore, on multilane roads, medians that were painted (but not raised) and center two-way left-turn lanes did not offer significant safety benefits to pedestrians, compared to multilane roads with no median at all.

There did appear to be some regional effect. Marked and unmarked crosswalks in western U.S. cities had a significantly higher pedestrian crash rate than eastern U.S. cities (after controlling for pedestrian exposure, number of lanes, median type, and other site conditions). The reason(s) for these regional differences in pedestrian crash rate is not known, although it could be related to regional differences in driver and pedestrian behavior, higher vehicle speeds in western cities, differences in pedestrian-related laws or enforcement levels, variations in roadway design features, and/or other factors. However, this effect was only marginally significant in the final crash prediction model, and excluding it from the model had little effect on the model results.

All of the variables related to pedestrian crashes (i.e., pedestrian volume, traffic ADT, number of lanes, existence of median and median type, and region of the country) then were included in the models for determining the effects of marked and unmarked sites. Factors having no significant effect on pedestrian crash rate included: area (e.g., residential, central business district (CBD)), location (i.e., intersection versus midblock), speed limit, traffic operation (one-way or two-way), condition of crosswalk marking (excellent, good, fair, or poor), and crosswalk marking pattern (e.g., parallel lines, ladder type, zebra stripes). One may expect that crosswalk marking condition may not necessarily be related to pedestrian crash rate, since the condition of the markings may have varied over the 5-year analysis period, and the condition of the markings was observed only once. Furthermore, in some regions, the crosswalk markings may be less visible during or after rain or snow storms. It is also recognized, however, that some agencies may maintain and restripe crosswalks more often than other agencies included in the study sample.

MARKED AND UNMARKED CROSSWALK COMPARISONS

The results revealed that on two-lane roads, there were no significant differences in pedestrian crashes for marked and unmarked crosswalk sites. In other words, pedestrian safety on two-lane roads was not found to be different, whether the crosswalk was marked or unmarked. This conclusion is based on a sample size of 914 crossing sites on two-lane roads (out of 2,000 total sites). Specifically, binomial comparison of pedestrian crash rates were computed for marked and unmarked sites within subsets by ADT, median type, and number of lanes, as shown in figure 18.

On multilane roads with ADT of 12,000 or less, there were also no differences in pedestrian crash rates between marked and unmarked sites. On multilane roads with no raised medians and ADTs greater than 12,000, sites with marked crosswalks had higher pedestrian crash rates than unmarked crossings. On multilane roads (roads with three to eight lanes) with raised medians and vehicle ADTs greater than 15,000, a significantly higher pedestrian crash rate was associated with marked crosswalk sites compared to unmarked sites.

Best-fit curves for multilane undivided roads were produced for pedestrian crashes (per million pedestrian crossings) at marked and unmarked crosswalks as a function of vehicle volume (ADT), as shown in figure 19. The data points of figure 19 were obtained by aggregating sites into traffic volume categories. Since each marked crosswalk site and its matched comparison (unmarked) site usually had the same traffic volume, each traffic volume category usually contained the same number of marked and unmarked sites (there were a few exceptions). Pedestrian crash rates were computed based on total pedestrian crashes and total pedestrian crossings within each traffic volume category. In figure 19, these rates are plotted at the midpoints of the traffic volume categories. Smooth curves were then fit to the data points. Similar analyses were conducted for multilane divided roads. A final negative binomial model was also developed. The analysis for multilane undivided roads revealed that:

• For traffic volumes (ADTs) of about 10,000 or less, pedestrian crash rates were about the same (i.e., less than 0.25 pedestrian crashes per million pedestrian crossings) between marked and unmarked crosswalks.
• For ADTs greater than 10,000, the pedestrian crash rate for marked crosswalks became increasingly higher as the ADTs increased. The pedestrian crash rate at unmarked crossings increased only slightly as the ADTs increased.

Figure 18. Pedestrian crash rate versus type of crossing.

Figure 19. Pedestrian crash rates by traffic volume for multilane crossings with no raised medians-marked versus unmarked crosswalks.

Note that each point on the graph in figure 19 represents dozens of sites, that is, all of the sites corresponding to the given ADT group. For example, the data point for marked crosswalks with ADTs greater than 15,000 corresponds to more than 400 sites. All analyses in this study took into account differences in pedestrian crossing volume, traffic volume, and other important site variables.

These results may be somewhat expected. Wide, multilane streets are difficult for many pedestrians to cross, particularly if there is an insufficient number of adequate gaps in traffic due to heavy traffic volume and high vehicle speed. Furthermore, while marked crosswalks in themselves may not increase measurable unsafe pedestrian or motorist behavior (based on the Knoblauch et al. and Knoblauch and Raymond studies^(13,14)) one possible explanation is that installing a marked crosswalk may increase the number of at-risk pedestrians (particularly children and older adults) who choose to cross at the uncontrolled location instead of at the nearest traffic signal.

The pedestrian crossing counts at the 1,000 marked crosswalks and 1,000 unmarked comparison crossings in this study may partially explain the difference. Overall, 66.1 percent of the observed pedestrians crossed at marked crosswalks, compared to 33.9 percent at unmarked crossings. More than 70 percent of pedestrians under age 12 and above age 64 crossed at marked crosswalks, while about 35 percent of pedestrians in the 19- to 35-year-old range crossed at unmarked crossings, as shown in figure 20. The age group of pedestrians was estimated based on site observation.

An even greater percentage of older adults (81.3 percent) and young children (76.0 percent) chose to cross in marked crosswalks on multilane roads compared to two-lane roads. Thus, installing a marked crosswalk at an already undesirable crossing location (e.g., wide, high-volume street) may increase the chance of a pedestrian crash occurring at such a site if a few at-risk pedestrians are encouraged to cross where other adequate crossing facilities are not provided. This explanation might be evidenced by the many calls to traffic engineers from citizens who state, "Please install a marked crosswalk so that we can cross the dangerous street near our house." Unfortunately, simply installing a marked crosswalk without other more substantial crossing facilities often does not result in the majority of motorists stopping and yielding to pedestrians, contrary to the expectations of many pedestrians.

On three-lane roads (i.e., one lane in each direction with a center two-way left-turn lane), the crash risk was slightly higher for marked crosswalks compared to unmarked crosswalks, but this difference was not significant (based on a sample size of 148 sites).

CRASH TYPES

The greatest difference in pedestrian crash types that occurred at marked and unmarked crosswalks involved multiple-threat crashes. A multiple-threat crash involves a driver stopping in one lane of a multilane road to permit pedestrians to cross, and an oncoming vehicle (in the same direction) strikes the pedestrian who is crossing in front of the stopped vehicle. This crash type involves both the pedestrian and driver failing to see each other in time to avoid the collision (see figure 21). To avoid multiple-threat collisions, drivers should slow down and look around stopped vehicles in the adjacent travel lane, and pedestrians should stop at the outer edge of a stopped vehicle and look into the oncoming lane for approaching vehicles before stepping into the lane.

Figure 20. Percentage of pedestrians crossing at marked and unmarked crosswalks by age group and road type.

Figure 21. Illustration of multiple-threat pedestrian crash.

A total of 17.6 percent (33 out of 188) of the pedestrian crashes in marked crosswalks were classified as multiple threat. None of the 41 pedestrian crashes in unmarked crosswalks was a multiple-threat crash. This finding may be the result of one or more of the following factors:

• Drivers may be more likely to stop and yield to pedestrians in marked crosswalks compared to unmarked crossings, since at least one motorist must stop for a pedestrian to set up a multiple-threat pedestrian collision. Also, pedestrians may be more likely to step out in front of oncoming traffic in a marked crosswalk than at an unmarked location in some instances.
• A second explanation is related to the fact that most of the total pedestrians who are crossing multilane roads are crossing in a marked crosswalk (66.1 percent), as shown earlier in figure 14. Furthermore, of the pedestrian age groups most at risk (the young and the old), an even greater proportion of these pedestrians are choosing to cross multilane roads in marked crosswalks (76 percent and 81.3 percent, respectively).
• Another possible explanation could be that some pedestrians crossing in a marked crosswalk may be less likely to search properly for vehicles (compared to an unmarked crossing) when stepping out past a stopped vehicle and into an adjacent lane (i.e., pedestrians not realizing that they need to search for other oncoming vehicles after one motorist stops for them).

Further research on pedestrian and motorist behavior could help to gain a better understanding of the causes and potential effects of countermeasures (e.g., advance stop lines) related to these crashes. There is also a need to examine the current laws and level of police enforcement (and a possible need for changes in the laws) on motorist responsibility to yield to pedestrians and how these laws differ between States. A distribution of pedestrian crash types, which includes all of the 229 pedestrian collisions at the 2,000 study sites, is shown in figure 22.

Motorists failing to yield (on through movements) represented a large percentage of pedestrian crashes in marked crosswalks (41.5 percent) and unmarked crosswalks (31.7 percent). Likewise, vehicle turn and merge crashes, also generally the fault of the driver, accounted for 19.2 percent (marked crosswalks) and 12.2 percent (unmarked crosswalks) of such crashes (see figure 22). These results indicate a strong need for improved driver enforcement and education programs that emphasize the importance of yielding or stopping for pedestrians. More pedestrian-friendly roadway designs may also be helpful in reducing such crashes by slowing vehicles, providing pedestrian refuge (e.g., raised medians), and/or better warning to motorists about pedestrian crossings.

Figure 22. Pedestrian crash types at marked and unmarked crosswalks.

A substantial proportion of pedestrian crashes involved dartout, dash, and other types of crashes in which the pedestrian stepped or ran in front of an oncoming vehicle at unmarked crosswalks (23 of 41, or 56.1 percent) and a lesser proportion occurred at marked crosswalks (41 of 188, or 21.8 percent). Police officers sometimes unjustifiably assign fault to the pedestrian, which suggests the need for more police training. Specifically, it may be questioned why so many pedestrian crashes were designated by the police officer as "pedestrian fails to yield," since in most States, motorists are required legally to yield the right-of-way to pedestrians who are crossing in marked or unmarked crosswalks. Of course, some State ordinances do specify that pedestrians also bear some responsibility for avoiding a collision by not stepping out into the street directly into the path of an oncoming motorist who is too close to the crosswalk to stop in time to avoid a collision. It is likely that police officers often rely largely on the statement of the motorist (e.g., "the pedestrian ran out in front of me" or "came out of nowhere") in determining fault in such crashes, particularly when the driver was not paying proper attention to the road, the pedestrian is unconscious, and there are no other witnesses at the scene. However, it is also true that a major contributing factor is the unsafe behavior of pedestrians. Dartouts, dashes, and failure of the pedestrians to yield were indicated by police officers as contributing causes in 27.9 percent (64 of 229) of the pedestrian crashes at the study sites. These results are indicative of a need for improved pedestrian educational programs, which is in agreement with recommendations in other important studies related to improving the safety of vulnerable road users. ⁽³³⁾ Furthermore, speeding drivers often contribute to dartout crashes, in addition to unsafe pedestrian behaviors. Creating more pedestrian-friendly crossings by including curb extensions, traffic-calming measures, and other features may also be useful in reducing many of these crashes. It should be mentioned that alcohol use by pedestrians and motorists may also contribute to pedestrian crash experience. However, reliable information on alcohol involvement was not available from local crash reports; therefore, such analysis was not possible for this study.

CRASH SEVERITY

An analysis was conducted to compare pedestrian crash severity on marked and unmarked crosswalks (figure 23). Crash severity did not differ significantly between marked and unmarked crosswalks on two-lane roads. On multilane roads, there was evidence of more fatal (type K) and type A injury pedestrian crashes at marked crosswalks compared to unmarked crosswalks, although the sample sizes were too small for statistical reliability. This result probably is due to older pedestrians being more likely than other age groups to walk in marked rather than unmarked crosswalks. Furthermore, older pedestrians are much more likely to sustain fatal and serious injuries than younger pedestrians. As mentioned earlier, speed limits of 56.3 km/h (35 mi/h) and higher were associated with a greater percentage of fatal and/or type A injuries (43 percent), whereas sites with lower speed limits had 23 percent of pedestrian crashes resulting in fatal and/or type A injuries.

Figure 23. Severity distribution of pedestrian collisions for marked and unmarked crosswalks.

LIGHTING AND TIME OF DAY

Nighttime pedestrian crash percentages were about the same at marked and unmarked crosswalks (approximately 30 percent). In terms of time of day, the percentage of pedestrian crashes in marked crosswalks tended to be higher than for unmarked crosswalks during the morning (6 to 10 a.m.) and afternoon (3 to 7 p.m.) peak periods, but lower in the midday (10 a.m. to 3 p.m.) and evening (7 p.m. to midnight) periods (figure 24). This is probably because pedestrians are more likely to cross in marked crosswalks than in unmarked crossings during peak traffic periods (e.g., walking to and from work) than at other times. As shown in figure 25, little difference is noticeable between pedestrian collisions for marked and unmarked crosswalks with respect to light condition. However, it is apparent that adequate nighttime lighting should be provided at marked crosswalks to enhance the safety of pedestrians crossing at night.

Figure 24. Distribution of pedestrian collisions by time of day for marked and unmarked crosswalks.

Figure 25. Pedestrian collisions by light condition for marked and unmarked crosswalks.

AGE EFFECTS

A separate analysis of pedestrian crashes and crossing volumes by age of pedestrian was conducted (figure 26). For virtually every situation studied, pedestrians age 65 and older were overrepresented in pedestrian crashes compared to their relative crossing volumes. Figures 27-30 show the relative proportion of crashes and exposure for various age groups for marked crosswalks on two-lane and multilane roads. For a given age group, when the proportion of crashes exceeds the proportion of exposure, then crashes are overrepresented; that is, pedestrians in that population group are at greater risk of being in a pedestrian crash than would be expected from their volume alone.

The pedestrian age groups younger than 65 showed no clear increase in crash risk compared to their crossing volumes. One possible reason that young pedestrians were not overly involved in crash occurrences is the fact that many crashes involving young pedestrians (particularly ages 5 to 9) occur on residential streets, whereas this study did not include school crossings; most sites were drawn from collector and arterial streets (where marked crosswalks exist) that are less likely to be frequented by unescorted young children. Also, some of the young children counted in this study were crossing with their parents or other adults, which may have reduced their risk of a crash. Some of the possible reasons that older pedestrians are at greater risk when crossing streets compared to other age groups are that older adults are more likely (as an overall group) than younger pedestrians to have:

• Slower walking speeds (and thus greater exposure time).
• Visual and/or hearing impairments.
• Difficulty in judging the distance and speed of oncoming traffic.
• More difficulty keeping track of vehicles coming from different directions, including turning vehicles.
• Inability to react (e.g., stop, dodge, or run) as quickly as younger pedestrians in order to avoid a collision under emergency conditions.

Figures 27-30. Percentage of crashes and exposure by pedestrian age group and roadway type at uncontrolled marked and unmarked crosswalks.

DRIVER AND PEDESTRIAN BEHAVIOR AT CROSSWALKS

A companion study was conducted by Knoblauch et al. on pedestrian and motorist behavior and on vehicle speed before and after crosswalk installation at sites in Minnesota, New York, and Virginia (on two-lane and three-lane streets) to help gain a better understanding of the effects of marked crosswalks versus unmarked crosswalks. ⁽¹³⁾ The study results revealed that very few motorists stopped or yielded to pedestrians either before or after marked crosswalks were installed. After marked crosswalks were installed, there was a small increase in pedestrian scanning behavior before stepping out into the street. Also, there was approximately a 1.6-km/h (1-mi/h) reduction in vehicle speed after the marked crosswalks were installed. ⁽¹³⁾ These behavioral results tend to contradict the false sense of security claims attributed to marked crosswalks, since observed pedestrian behavior actually improved after marked crosswalks were installed at the study sites. However, measures such as pedestrian awareness and an expectation that motorists will stop for them cannot be collected by field observation alone. Installing marked crosswalks or other measures can affect pedestrian level of service if the measures increase the number of motorists who stop and yield to pedestrians. Furthermore, a greater likelihood of motorist stopping can also setup more multiple threat crashes on multilane roads. Future studies using focus groups of pedestrians and questionnaires completed by pedestrians in the field could shed light on such measures.

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