National Academies Press: OpenBook

Improving Pedestrian Safety at Unsignalized Crossings (2006)

Chapter: Chapter 3 - Review of Pedestrian Crossing Treatments

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Suggested Citation:"Chapter 3 - Review of Pedestrian Crossing Treatments." National Academies of Sciences, Engineering, and Medicine. 2006. Improving Pedestrian Safety at Unsignalized Crossings. Washington, DC: The National Academies Press. doi: 10.17226/13962.
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Suggested Citation:"Chapter 3 - Review of Pedestrian Crossing Treatments." National Academies of Sciences, Engineering, and Medicine. 2006. Improving Pedestrian Safety at Unsignalized Crossings. Washington, DC: The National Academies Press. doi: 10.17226/13962.
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Suggested Citation:"Chapter 3 - Review of Pedestrian Crossing Treatments." National Academies of Sciences, Engineering, and Medicine. 2006. Improving Pedestrian Safety at Unsignalized Crossings. Washington, DC: The National Academies Press. doi: 10.17226/13962.
×
Page 18
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Suggested Citation:"Chapter 3 - Review of Pedestrian Crossing Treatments." National Academies of Sciences, Engineering, and Medicine. 2006. Improving Pedestrian Safety at Unsignalized Crossings. Washington, DC: The National Academies Press. doi: 10.17226/13962.
×
Page 19
Page 20
Suggested Citation:"Chapter 3 - Review of Pedestrian Crossing Treatments." National Academies of Sciences, Engineering, and Medicine. 2006. Improving Pedestrian Safety at Unsignalized Crossings. Washington, DC: The National Academies Press. doi: 10.17226/13962.
×
Page 20
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Suggested Citation:"Chapter 3 - Review of Pedestrian Crossing Treatments." National Academies of Sciences, Engineering, and Medicine. 2006. Improving Pedestrian Safety at Unsignalized Crossings. Washington, DC: The National Academies Press. doi: 10.17226/13962.
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Page 21

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16 Initial research efforts were to review available information on pedestrian crossing treatments and designs. Several recent publications provide a good overview on various crossing treatments, including the following: • 2001 ITE informational report on Alternative Treatments for At-Grade Pedestrian Crossings (26) and • 2002 FHWA report on Pedestrian Facilities Users Guide (27). The findings identified in this project from recent research are documented in the following appendixes: • Appendix C presents the literature review. • Information on current practices since the 2001 ITE report is included in Appendix D. • Each study in the literature review is discussed in Appendix E. • Appendix F discusses pedestrian crossing installation crite- ria used by entities in several countries. Criteria identified during this joint TCRP/NCHRP project is summarized at the end of the appendix. This chapter summarizes the major evaluation findings for various pedestrian crossing treatments at uncontrolled loca- tions and provides the research team’s interpretation of these findings. Combinations of Treatments Several evaluations have tested a combination of crossing treatments and found these treatments to be more effective when used together systematically. For example, a study in St. Petersburg, Florida, found that advanced yield lines, Yield Here to Pedestrian signs, and pedestrian prompting signs were most effective when used together (28). The research team believes that the safest and most effective pedestrian crossings often use several traffic control devices or design elements to meet the information and control needs of both motorists and pedestrians. For example, consider the following desirable characteris- tics for a pedestrian crossing: • The street crossing task is made simple and convenient for pedestrians. • The crossing location and any waiting or crossing pedes- trians have excellent visibility. • Vehicle speeds are slowed or controlled in the area of the pedestrian crossing. • Vehicle drivers are more aware of the presence of the crosswalk. • Vehicle drivers yield the right-of-way to legally crossing pedestrians. • Pedestrians use designated crossing locations and obey applicable state and local traffic laws. In a complex (e.g., multi-lane, high-speed, high-volume) street environment, it probably will be difficult to provide these characteristics with a single simple treatment, i.e., com- plex street environments may require several different treat- ments intended to serve different purposes. For example, one might consider these treatments on a multi-lane, high-vol- ume arterial street: • A median refuge island to make the street crossing easier and more convenient; • Advanced yield lines to improve the visibility of crossing pedestrians; • Removal of parking and installation of curb extensions to improve visibility; • Pedestrian-activated flashing beacons to warn motorists of crossing pedestrians; • Motorist signs to indicate that pedestrians have the legal right-of-way; C H A P T E R 3 Review of Pedestrian Crossing Treatments

• Pedestrian signs to encourage looking behavior, crosswalk compliance, and pushbutton activation; • In-pavement warning lights with advance signing to inform drivers of the crossing; and • “Countdown signals”with a pedestrian (Walk/Don’t Walk) signal if appropriate for the treatment (e.g., high-intensity activated crosswalk [HAWK] signal or other pedestrian traffic control signals). Streets with lower speeds or traffic volumes may not require multiple treatments to be safe and effective. In these less complex street environments, single treatments may be just as safe and effective as multiple treatments. Traffic Signal and Red Beacon Displays Pedestrian devices that include a red signal indication vary. These devices include traffic signals and displays with solid or flashing red beacons. There is limited experience with inter- section pedestrian signals (commonly known as “half signals”) because their current operation is limited to a few cities (e.g., Seattle and Portland). They are also used in some provinces of Canada (British Columbia being the most notable). For vehicle control, these pedestrian signals typically use a traditional traffic signal head on the major street and a Stop sign on the minor street (if applicable). Midblock pedestrian signals are used in Europe (as well as Canada and the United States), where they are referred to as pedestrian crossovers (Toronto) or pelicans or puffins (Europe). Pedestrian move- ments across the major street are controlled by traditional pedestrian Walk/Don’t Walk signals for red signal indication devices. The signal display sequences for these pedestrian signals vary among installations. Half signals in the city of Seattle dwell in steady green and then cycle to steady yellow and then steady red when activated by a pedestrian. The HAWK signals in Tucson (see Figure 7) are modeled after emergency vehicle beacons and are dark until activated by a pedestrian; then they cycle through flashing yellow, steady yellow, steady red, and then flashing red. Half signals in the Vancouver area of British Columbia dwell in flashing green and, on activation, steady green (for some installations), steady yellow, and then steady red. The midblock pedestrian signal in Los Angeles shows a green arrow, cycles to a steady yellow, and then cycles to steady red during the walk interval. During the flashing Don’t Walk interval, drivers see a flashing red indication and, after stopping, may proceed if the crosswalk is not occupied. Despite differences in signal operation, the pedestrian or half signals have been documented as successful in encourag- ing motorists to yield to pedestrians along high-volume and/or high-speed streets. For example, several studies (28-30), including the study done for this TCRP/NCHRP project (see Appendix L), have documented driver yielding in the 90 to 100 percent range. The steady red signal indication provides a clear regulatory message that typically receives a more uniform control response than warning signs or flash- ing beacons. Critics of the concept have suggested that vehi- cle crashes will increase because of signalization on the major street or conflicting control messages from the signal and Stop sign. However, crash analyses in the city of Seattle have documented that, with consistent operation, the half signals can actually reduce vehicle-vehicle crashes and pedestrian- vehicle conflicts (31-34). Inconsistent and somewhat confus- ing operation (e.g., flashing green) of half signals in British Columbia has generated poor compliance with Stop signs on the minor street (35). In summary, devices with a red signal indication show promise as a pedestrian-crossing treatment for high-volume, high-speed arterial streets. The field studies conducted in this project indicated that these red signal or beacon devices were most effective at prompting motorist yielding (all sites had motorist compliance greater than 90 percent) on high- volume, high-speed streets. It may be necessary to determine the most effective signal indication display sequence, as well as the traffic conditions that would accommodate the use of minor street Stop sign control and major street signal control. Flashing Beacons The use of flashing beacons for pedestrian crossings is prevalent in the United States (see Figure 8). In some instances, there are concerns that the overuse of flashing bea- cons or the continuous flashing at specific locations has 17 Figure 7. HAWK signal in Tucson, Arizona.

diluted their effectiveness in warning motorists of conditions. Flashing beacons have been installed in numerous ways: • At the pedestrian crossing, both overhead and side mounted; • In advance of the pedestrian crossing, both overhead and side mounted; • In conjunction with or integral within other warning signs; and • In the roadway pavement itself (see next section on in- roadway warning lights). The operations for flashing amber beacons may also vary, including the following: • Continuous flash mode; • Pedestrian activated using manual pushbuttons; • Passive pedestrian detection using automated sensors (e.g., microwave or video); and • Different flash rates, sequences, or strobe effects. The experience with flashing beacons has been mixed, as would be expected when they have been installed in numerous different ways. Several studies have shown that intermittent (typically activated using a manual pushbutton or automated sensor) flashing beacons provide a more effective response from motorists than continuously flashing beacons (36, 37). These beacons do not flash constantly; thus, when they are flashing, motorists can be reasonably sure that a pedestrian is crossing the street. With pedestrian activation, special signing may be necessary to ensure that pedestrians consistently use the pushbutton activation. Alternatively, automated pedestrian detection has been used with some success, but typically requires extra effort in installation and maintenance. Overhead flashing beacons appear to have the best visibility to motorists, particularly when used both at and in advance of the pedestrian crossing.Many installations have used both over- head and side-mounted beacons. The effectiveness of the flash- ing beacons in general, however, may be limited on high-speed or high-volume arterial streets. For example, overhead flashing beacons have produced driver yielding behavior that ranges from 30 to 76 percent,with the median values falling in the mid- 50 percent range (26, 36-38). The evaluations did not contain enough information to attribute high or low driver yielding val- ues to specific road characteristics. The field studies conducted in this TCRP/NCHRP project found a similarly wide range of motorist yielding values (25 to 73 percent), with the average value for all flashing beacons at 58 percent. The analysis of site conditions and traffic variables also found that traffic speeds, traffic volumes, and number of lanes have a statistically signifi- cant effect on driver yielding behavior on arterial streets. In-Roadway Warning Lights As a specific design case of flashing beacons, in-roadway warning light installations have proliferated in their 10 years of existence. Their use originated in California and Washington State but has spread to numerous other places in the United States (see Figure 9). In-roadway warning lights are mounted in the pavement near the crosswalk markings such that they typi- cally protrude above the pavement less than 0.5 in (1.3 cm). As with flashing beacons, the experience with in-roadway warning lights has been mostly positive, with a few negative results. Many early and some current equipment designs for the in-roadway warning lights have been problematic. Some of the problems encountered are as follows: • Snow plows have damaged the flashing light enclosures, • Light lenses have become dirty from road grit and have required regular cleaning, and • Automated pedestrian detection has not operated effectively. 18 Figure 8. Pedestrian-activated overhead flashing beacon. Figure 9. In-roadway warning lights and supplemental signs and beacons in Austin, Texas.

Many of the early problems have been resolved through the past 10 years of experience, but some cities continue to be cautious in specifying more in-roadway warning lights until they have long-term experience. Some cities have noted their preference for overhead flashing beacons instead of in-road- way lights because of poor visibility issues when traffic is queued in front of the in-roadway lights (37, 39). Another concern is that in very bright sunlight, the flashing lights are difficult for drivers to see. For most of the installations, in-roadway warning lights have increased driver yielding to the 50 to 90 percent range (38, 40-44). Additionally, the in-roadway warning lights typ- ically increase the distance that motorists first brake for a pedestrian crossing, indicating that motorists recognize the pedestrian crossing and the need to yield sooner (40-43). These results have been even more dramatic at night when the in-roadway warning lights are highly visible. For a few instal- lations, driver yielding decreased or did not increase above 30 percent (38, 45). The research team hypothesizes that these installations were most likely inappropriate and other cross- ing treatments would have been more effective. The research team did not include in-roadway warning lights in this TCRP/NCHRP project’s field studies because of the abun- dance of evaluation results in the literature. Motorist Warning Signs and Pavement Markings Motorist warning signs and pavement markings used as pedestrian crossing treatments can take many shapes and forms; examples are as follows: • Animated or roving eyes, • Advance yield or stop lines, • Crossing flags carried by pedestrians (see Figure 10), • Yield to Pedestrian and Stop Here for Pedestrian signs, and • Internally illuminated crosswalk signs. The experience with these types of warning signs and pavement markings has generally been modest, with a few treatments showing more promise than others. The strength of the message that these traffic control devices sends to motorists is mostly considered a warning (i.e.,“watch out for pedestrians” or “avoid pedestrians”). In many cases, the research team hypothesizes that motorists receive these warning messages and consider yielding or stopping for pedestrians as a courtesy and not the law (it is the law in many states). The research team further hypothesizes that motorists are less willing to extend this “courtesy” to pedes- trians on high-speed, high-volume roadways because they think (1) they are being delayed unnecessarily and (2) these high-speed, high-volume roadways are the domain of auto- mobiles and not pedestrians. As indicated, several of the crossing treatments show more promise than others. Advance yield lines place the traditional stop or yield line 30 to 50 ft (9.1 to 15.2 m) in advance of the crosswalk and are often accompanied by Yield Here to Pedes- trian signs. Advance yield lines address the issue of multiple threat crashes on multi-lane roadways, where one vehicle may stop for a crossing pedestrian but inadvertently screens the pedestrian from the view of vehicles in other lanes. Several studies have documented that advance yield lines decrease pedestrian-vehicle conflicts and increase driver yielding at greater distances from the crosswalk (28, 46-48). In-street pedestrian crossing signs and high-visibility signs and markings were two types of treatments included in this TCRP/NCHRP project’s study sites. The field studies indicated that in-street signs had relatively high motorist yielding (ranged from 82 to 91 percent, for an average of 87 percent); however, all three study sites were on two-lane streets with posted speed limits of 25 or 30 mph (40 or 48 km/h). The results for high-visibility signs and markings also demon- strated the effects of higher posted speed limits. One site with high-visibility signs and markings and a posted speed limit of 25 mph (40 km/h) had a motorist yielding value of 61 percent. 19 Figure 10. Pedestrian crossing flags in Salt Lake City, Utah.

However, the other two study sites with high-visibility signs and markings and a posted speed limit of 35 mph (55 km/h) had motorist yielding values of 10 and 24 percent, for an aver- age of 17 percent. Several cities (e.g., Salt Lake City, Utah; Kirkland, Wash- ington; and Berkeley, California) use fluorescent orange flags that are carried by crossing pedestrians. The research team found no formal studies in the literature on the effectiveness of crossing flags; however, anecdotal information has indi- cated that these crossing flags are effective in improving driver yielding behavior. The flags in Salt Lake City are used mostly on streets near the downtown area that have speed limits of 30 mph (48 km/h) or less. Several of these streets, however, are multi-lane, high-volume arterials. Field studies conducted in this TCRP/NCHRP project found pedestrian crossing flags in Salt Lake City and Kirkland to be moderately effective. The study sites with crossing flags had motorist yielding rates that ranged from 46 to 79 percent, with an average of 65 percent compliance. Several of the study sites had four or more lanes with speed limits of 30 mph (48 km/h) or 35 mph (55 km/h). Crosswalk Pavement Markings Until recently, a San Diego study from the early 70s has served as the authoritative reference on marked crosswalks (49). The San Diego study indicated that nearly six times as many crashes occurred in marked crosswalks as in unmarked crosswalks. After accounting for pedestrian usage, the crash ratio was reduced to about two to three times as many crashes in marked crosswalks as in unmarked crosswalks. Some engi- neers interpreted these results to mean that they should install fewer crosswalks (i.e., not mark crosswalks) for pedestrian crossings than more (e.g., install treatments such as flashing beacons, advanced yield lines, and median refuge islands, in addition to pavement markings). In a 2002 study by the Highway Safety Research Center (HSRC), the authors found the crash experience of marked versus unmarked crosswalks at 1,000 locations in 16 states comparable with the San Diego results (50). After adjusting for various traffic and pedestrian characteristics, the authors found that the risk of a pedestrian-vehicle crash was 3.6 times greater at uncontrolled intersections with a marked crosswalk than with an unmarked crosswalk. However, the authors took the study results one step further by producing a matrix that indicates under what conditions (i.e., geometry, speed, and traffic volume) marked crosswalks alone are insufficient and other pedestrian crossing improvements are needed. Thus the 2002 HSRC study does not leave interpretation of the results open but instead suggests more crossing improve- ments in certain multi-lane, high-volume, high-speed road- way environments. Other studies have confirmed the higher crash rates at marked versus unmarked crosswalks (51, 52). A study of 104 locations in Los Angeles indicated that removing marked crosswalks reduced the total number of vehicle-pedestrian crashes at the formerly marked crosswalks as well as nearby unmarked crosswalks (51, 52). This result suggested that pedestrian-vehicle crashes were not simply being moved to nearby unmarked crosswalks when marked crosswalks were removed. Two studies have suggested that speeds are lower at loca- tions with crosswalk pavement markings (53, 54). However, the documented speed reductions were so small (e.g., 0.2 to 2 mph [0.32 to 3.2 km/h]) as to be practically negligible. These studies also found that blatantly aggressive pedestrian behav- ior did not increase with installation of pavement marking; however, the studies did not address basic looking behavior that would indicate a decrease in pedestrian attentiveness while crossing at marked versus unmarked crosswalks. Roadway Design Elements Several other design elements are considered effective at pedestrian crossings, including median refuge islands, curb extensions, and adequate nighttime lighting. In many cases, these design elements are used in conjunction with other crossing treatments as described above. For example, median refuge islands are considered very effective for pedestrian crossings on multi-lane streets. The 2002 HSRC crosswalk study found that multi-lane streets with median refuge islands had pedestrian crash rates two to four times lower than multi-lane streets without median refuge islands (50). The field studies from this TCRP/NCHRP project indicated a wide range of motorist yielding at study sites with median refuge islands and marked crosswalks. For six sites, the motorist yielding ranged from 7 to 75 percent, with an aver- age of 34 percent. As with other pedestrian crossing treat- ments, the number of through lanes and posted speed limit were statistically significant in explaining the wide range of effectiveness (as measured by motorist yielding). Curb exten- sions improve the visibility of pedestrians waiting to cross, as well as decrease their exposure by decreasing the crossing dis- tance and time. Adequate nighttime lighting better illumi- nates crossing pedestrians as well as the crossing itself. Summary Numerous engineering treatments and design elements can be used to improve pedestrian crossings along high-volume, high-speed roadways. In a literature review, the research team found that a combination of crossing treatments is likely to be more effective in meeting the information and control needs of pedestrians and motorists. For example, the following might be 20

appropriate along a high-volume, multi-lane arterial street: median refuge island, advanced yield lines, curb extensions with parking restrictions nearby, overhead flashing beacons, and high-visibility motorist and pedestrian signs. The litera- ture review revealed that several experimental traffic control devices that display red signal or beacon indications were effec- tive at prompting motorist compliance and increasing pedes- trian safety. Evaluations of other traffic control devices that provide a warning (e.g., signs and flashing beacons or lights) had wide ranges of effectiveness, with wider, busier streets having lower motorist compliance with marked crosswalks. The field studies conducted for this TCRP/NCHRP project supported the main findings from the literature review, in that red signal or beacon devices were more effective than all other devices evaluated, with motorist compliance values between 90 and 100 percent at all study sites. With other warning devices, the research team found a wide range of motorist compliance values. Further, the analysis found that the number of lanes and posted speed limit were statistically significant in explaining part of this wide range in treatment effectiveness. 21

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TRB's Transit Cooperative Research Program (TCRP) and National Cooperative Highway Research Program have jointly produced and published Improving Pedestrian Safety at Unsignalized Crossings. The product, which can be referred to as TCRP Report 112 or NCHRP Report 562, examines selected engineering treatments to improve safety for pedestrians crossing high-volume and high-speed roadways at unsignalized locations. The report presents the edited final report and Appendix A. TCRP Web-Only Document 30/NCHRP Web-Only Document 91 (Pedestrian Safety at Unsignalized Crossings: Appendices B to O) contains the remaining appendixes of the contractor's final report.

A summary of TCRP Report 112/NCHRP Report 562 as published in the July-August 2007 issue of the TR News is available online.

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