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20 However, the other two study sites with high-visibility signs Other studies have confirmed the higher crash rates at and markings and a posted speed limit of 35 mph (55 km/h) marked versus unmarked crosswalks (51, 52). A study of 104 had motorist yielding values of 10 and 24 percent, for an aver- locations in Los Angeles indicated that removing marked age of 17 percent. crosswalks reduced the total number of vehicle-pedestrian Several cities (e.g., Salt Lake City, Utah; Kirkland, Wash- crashes at the formerly marked crosswalks as well as nearby ington; and Berkeley, California) use fluorescent orange flags unmarked crosswalks (51, 52). This result suggested that that are carried by crossing pedestrians. The research team pedestrian-vehicle crashes were not simply being moved to found no formal studies in the literature on the effectiveness nearby unmarked crosswalks when marked crosswalks were of crossing flags; however, anecdotal information has indi- removed. cated that these crossing flags are effective in improving Two studies have suggested that speeds are lower at loca- driver yielding behavior. The flags in Salt Lake City are used tions with crosswalk pavement markings (53, 54). However, mostly on streets near the downtown area that have speed the documented speed reductions were so small (e.g., 0.2 to limits of 30 mph (48 km/h) or less. Several of these streets, 2 mph [0.32 to 3.2 km/h]) as to be practically negligible. These however, are multi-lane, high-volume arterials. Field studies studies also found that blatantly aggressive pedestrian behav- conducted in this TCRP/NCHRP project found pedestrian ior did not increase with installation of pavement marking; crossing flags in Salt Lake City and Kirkland to be moderately however, the studies did not address basic looking behavior effective. The study sites with crossing flags had motorist that would indicate a decrease in pedestrian attentiveness yielding rates that ranged from 46 to 79 percent, with while crossing at marked versus unmarked crosswalks. an average of 65 percent compliance. Several of the study sites had four or more lanes with speed limits of 30 mph Roadway Design Elements (48 km/h) or 35 mph (55 km/h). Several other design elements are considered effective at pedestrian crossings, including median refuge islands, curb Crosswalk Pavement Markings extensions, and adequate nighttime lighting. In many cases, Until recently, a San Diego study from the early 70s has these design elements are used in conjunction with other served as the authoritative reference on marked crosswalks crossing treatments as described above. For example, median (49). The San Diego study indicated that nearly six times as refuge islands are considered very effective for pedestrian many crashes occurred in marked crosswalks as in unmarked crossings on multi-lane streets. The 2002 HSRC crosswalk crosswalks. After accounting for pedestrian usage, the crash study found that multi-lane streets with median refuge ratio was reduced to about two to three times as many crashes islands had pedestrian crash rates two to four times lower in marked crosswalks as in unmarked crosswalks. Some engi- than multi-lane streets without median refuge islands (50). neers interpreted these results to mean that they should install The field studies from this TCRP/NCHRP project indicated a fewer crosswalks (i.e., not mark crosswalks) for pedestrian wide range of motorist yielding at study sites with median crossings than more (e.g., install treatments such as flashing refuge islands and marked crosswalks. For six sites, the beacons, advanced yield lines, and median refuge islands, in motorist yielding ranged from 7 to 75 percent, with an aver- addition to pavement markings). age of 34 percent. As with other pedestrian crossing treat- In a 2002 study by the Highway Safety Research Center ments, the number of through lanes and posted speed limit (HSRC), the authors found the crash experience of marked were statistically significant in explaining the wide range of versus unmarked crosswalks at 1,000 locations in 16 states effectiveness (as measured by motorist yielding). Curb exten- comparable with the San Diego results (50). After adjusting sions improve the visibility of pedestrians waiting to cross, as for various traffic and pedestrian characteristics, the authors well as decrease their exposure by decreasing the crossing dis- found that the risk of a pedestrian-vehicle crash was 3.6 times tance and time. Adequate nighttime lighting better illumi- greater at uncontrolled intersections with a marked crosswalk nates crossing pedestrians as well as the crossing itself. than with an unmarked crosswalk. However, the authors took the study results one step further by producing a matrix that Summary indicates under what conditions (i.e., geometry, speed, and traffic volume) marked crosswalks alone are insufficient Numerous engineering treatments and design elements can and other pedestrian crossing improvements are needed. be used to improve pedestrian crossings along high-volume, Thus the 2002 HSRC study does not leave interpretation of high-speed roadways. In a literature review, the research team the results open but instead suggests more crossing improve- found that a combination of crossing treatments is likely to be ments in certain multi-lane, high-volume, high-speed road- more effective in meeting the information and control needs of way environments. pedestrians and motorists. For example, the following might be
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21 appropriate along a high-volume, multi-lane arterial street: having lower motorist compliance with marked crosswalks. median refuge island, advanced yield lines, curb extensions The field studies conducted for this TCRP/NCHRP project with parking restrictions nearby, overhead flashing beacons, supported the main findings from the literature review, in that and high-visibility motorist and pedestrian signs. The litera- red signal or beacon devices were more effective than all other ture review revealed that several experimental traffic control devices evaluated, with motorist compliance values between 90 devices that display red signal or beacon indications were effec- and 100 percent at all study sites. With other warning devices, tive at prompting motorist compliance and increasing pedes- the research team found a wide range of motorist compliance trian safety. Evaluations of other traffic control devices that values. Further, the analysis found that the number of lanes and provide a warning (e.g., signs and flashing beacons or lights) posted speed limit were statistically significant in explaining had wide ranges of effectiveness, with wider, busier streets part of this wide range in treatment effectiveness.