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<br />CHAPTER 2. DATA COLLECTION AND ANALYSIS METHODOLOGY <br /> <br />For the purpose of assessing pedestrian safety, an ideal study design would involve removing all <br />crosswalks in several test cities, then randomly assigning sites for crosswalk markings and to serve as <br />unmarked control sites. However, due to liability considerations, it would be impossible to get the level <br />of cooperation needed from the cities to conduct such a study. Also, such random assignment of <br />crosswalk marking locations would result in many crosswalks not being marked at the most appropriate <br />locations. <br /> <br />Given such real-world constraints, a treatment and matched comparison site methodology was used to <br />quantify the pedestrian crash risk in marked and unmarked crosswalks. This study design allowed for <br />selection of a large sample of sites in cities throughout the United States where marked crosswalks and <br />similar unmarked comparison sites were available. At intersections, the unmarked crosswalk comparison <br />site was typically the opposite leg of the same intersection as the selected marked crosswalk site. For <br />each marked midblock crosswalk, a nearby midblock crossing location was chosen as the comparison site <br />on the same street (usually a block or two away) where pedestrians were observed to cross. (Even though <br />an unmarked midblock crossing is not technically or legally a crosswalk, it was a suitable comparison site <br />for a midblock crosswalk). The selection of a matched comparison site for each crosswalk site (typically <br />on the same route and very near the crosswalk site) helped to control for the effects of vehicle speeds, <br />traffic mix, and a variety of other traffic and roadway features. <br /> <br />A before-after study design was considered impractical because of regression-to-the-mean problems, <br />limited sample sizes of new crosswalk installations, and other factors. A total of 1,000 marked crosswalk <br />sites and 1,000 matched unmarked (comparison) crossing sites in 30 cities across the United States (see <br />figure 11) were selected for analysis. In this study, no attempt was made to actually paint any of the <br />1,000 unmarked crosswalks to determine any crash effects in a before and after study. Instead, a separate <br />(companion) study was conducted to monitor the effects of marking crosswalks on pedestrian and <br />motorist behaviors. These study results are discussed in chapter 3 of this report. <br /># <br /># <br />## <br /># <br /># <br />## <br /># <br /># <br />### <br />## <br />## <br />#### <br />## <br />### <br />## <br />Tempe <br />Topeka <br />Durham <br />Tucson <br />Austin <br />Seattle <br />Madison <br />Oakland <br />Raleigh <br />Orlando <br />Portland <br />Glendale <br />Milwaukee <br />Cambridge <br />Cleveland Baltimore <br />St. Louis <br />Pittsburgh <br />Cincinnati <br />Scottsdale <br />Fort Worth <br />NewOrleans <br />Gainesville <br />Winter Park <br />SanFrancisco <br />Salt Lake City <br />Phoenix <br />KansasCity <br /> <br />Figure 11. Cities and States used for study sample. <br /> 13