#02 - Cross Walk Discussion - Laserfiche WebLink

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5 marked and unmarked crosswalks. However, pedestrian volume was three times as high on the marked crosswalks as on the unmarked crosswalks. Herms stated: “Evidence indicates that the poor crash record of marked crosswalks is not due to the crosswalk being marked as much as it is a reflection on the pedestrian’s attitude and lack of caution when using the marked crosswalk.”(3) The Herms study, however, does not say what evidence the author had in mind regarding incautious pedestrian behavior. No behavioral data was presented. Other authors have advanced similar assertions with regard to pedestrian behavior in marked crosswalks. One of the issues involved in this crosswalk controversy relates to questions on the warrants used in San Diego, CA, to determine where to paint crosswalks. Specifically, the warrant directive for San Diego (January 15, 1962), established a point system calling for painting crosswalks when: (1) traffic gaps were fewer rather than more numerous; (2) pedestrian volume was high; (3) speed was moderate (not low, not high); and (4) other prevailing factors were present, such as previous crashes. Thus, it is possible that crosswalks may have been more likely to be painted in San Diego, CA, where the conditions were most ripe for pedestrian collisions (compared to sites which were unmarked). This could at least partly explain the increase in pedestrian crashes at marked crosswalks in the Herms study. Furthermore, the city of San Diego did not eliminate the use of marked crosswalks at uncontrolled locations based on the results of this study. The study recommended against the indiscriminate use of markings at uncontrolled locations. It should be mentioned that the Herms study did not distinguish whether the results would have differed, for example, for two-lane versus multilane roads, or for low-volume versus high-volume roads. Gibby et al. later revisited the issue.(5) Their report contains a thorough review of the literature and also includes an analysis of pedestrian crashes at 380 highway intersections in California. These intersections were picked after a detailed, multistep selection process in which more than 10,000 intersections were initially considered, and all but 380 were excluded. Their results showed that pedestrian crash rates at these 380 unsignalized intersections were 2 or 3 times higher in marked than in unmarked crosswalks when expressed as crash rates per unit pedestrian-vehicle volume. This study had the advantage of including a relatively large sample of intersections in cities throughout California, which may have minimized any data bias resulting from crosswalk marking criteria. However, it should be mentioned that, as with the Herms study, the Gibby study also did not determine how the results (between marked and unmarked crosswalks) might have differed for two-lane versus multilane roads, and/or for roads with low average daily traffic (ADT) compared to high ADT. Other studies have been conducted to address this issue. Gurnett described a project to remove painted stripes from some crosswalks following a bad crash experience.(6) This was a before-after study of three locations that were selected for crosswalk removal because they had a recent bad crash record. After removing the crosswalks, crashes decreased. Such results do not show the effect of removing the paint, but are very likely the result of the well-known statistical phenomenon of regression to the mean. It is also not clear whether pedestrian crossing volumes may have dropped after the marked crosswalks were removed.(6) Another study of marked crosswalks at unsignalized intersections was reported by the Los Angeles, CA, County Road Department in July 1967.(7) The county reported results of a before-after study of 89 intersections. Painted crosswalks were added at each site, but the basis for selecting those sites was not mentioned. Pedestrian crashes increased from 4 during the before period to 15 in the after period. The before-after design in this study is preferable to a treatment-control model in this instance, and better takes the selection effect into account. All sites that showed crash increases were intersections with an ADT rate above 10,900. Thus, at sites with a lower ADT rate, no change in pedestrian crashes was seen. Also, rear-end collisions increased from 31 to 58 after marked crosswalks were added. The report stated that rear-end collisions increased as traffic volume increased. Nevertheless, the study showed more