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<br />CHAPTER 3. STUDY RESULTS
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<br />SIGNIFICANT VARIABLES
<br />
<br />Poisson and negative binomial regression models were fit to pedestrian crash data from marked and
<br />unmarked crosswalks. These analyses showed that several factors in addition to crosswalk markings were
<br />associated with pedestrian crashes. Traffic and roadway factors found to be related to a greater frequency
<br />of pedestrian crashes included higher pedestrian volumes, higher traffic ADT, and a greater number of
<br />lanes (i.e., multilane roads with three or more lanes had higher pedestrian crash rates than two-lane
<br />roads). For this study, a center two-way left-turn lane was considered to be a travel lane and not a
<br />median.
<br />
<br />Surprisingly, after controlling for other factors (e.g., pedestrian volume, traffic volume, number of lanes,
<br />median type), speed limit was not significantly related to pedestrian crash frequency. Certainly, one
<br />would expect that higher vehicle speed would be associated with an increased probability of a pedestrian
<br />crash (all else being equal). However, the lack of association between speed limit and pedestrian crashes
<br />found in this analysis may be due to the fact that there was not much variation in the range of vehicle
<br />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
<br />km/h (25 to 35 mi/h). Another possible explanation, as hypothesized by Garder, is that pedestrians may
<br />be more careful when crossing streets with higher speed limits; that is, they may avoid short gaps on high-
<br />speed roads, which may minimize the effect of vehicle speed on pedestrian crash rates.(30) In terms of
<br />speed and crash severity, the analysis showed that speed limits of 56.3 km/h (35 mi/h) and greater were
<br />associated with a higher percentage of fatal and type A (serious or incapacitating) injuries (43 percent)
<br />compared to sites having lower speed limits (23 percent of the crashes resulting in fatal or type A
<br />injuries).
<br />
<br />The presence of a raised median or raised crossing island was associated with a significantly lower
<br />pedestrian crash rate at multilane sites with both marked and unmarked crosswalks. These results were in
<br />basic agreement with a major study by Bowman and Vecellio(31) and also a study by Garder(32) that found
<br />safety benefits for pedestrians due to raised medians and refuge islands, respectively. Furthermore, on
<br />multilane roads, medians that were painted (but not raised) and center two-way left-turn lanes did not
<br />offer significant safety benefits to pedestrians, compared to multilane roads with no median at all.
<br />
<br />There did appear to be some regional effect. Marked and unmarked crosswalks in western U.S. cities had
<br />a significantly higher pedestrian crash rate than eastern U.S. cities (after controlling for pedestrian
<br />exposure, number of lanes, median type, and other site conditions). The reason(s) for these regional
<br />differences in pedestrian crash rate is not known, although it could be related to regional differences in
<br />driver and pedestrian behavior, higher vehicle speeds in western cities, differences in pedestrian-related
<br />laws or enforcement levels, variations in roadway design features, and/or other factors. However, this
<br />effect was only marginally significant in the final crash prediction model, and excluding it from the model
<br />had little effect on the model results.
<br />
<br />All of the variables related to pedestrian crashes (i.e., pedestrian volume, traffic ADT, number of lanes,
<br />existence of median and median type, and region of the country) then were included in the models for
<br />determining the effects of marked and unmarked sites. Factors having no significant effect on pedestrian
<br />crash rate included: area (e.g., residential, central business district (CBD)), location (i.e., intersection
<br />versus midblock), speed limit, traffic operation (one-way or two-way), condition of crosswalk marking
<br />(excellent, good, fair, or poor), and crosswalk marking pattern (e.g., parallel lines, ladder type, zebra
<br />stripes). One may expect that crosswalk marking condition may not necessarily be related to pedestrian
<br />crash rate, since the condition of the markings may have varied over the 5-year analysis period, and the
<br />condition of the markings was observed only once. Furthermore, in some regions, the crosswalk
<br />markings may be less visible during or after rain or snow storms. It is also recognized, however, that
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