title: Safety network screening for municipalities with incomplete traffic volume data.
abstract: Safety network screening is used to identify road locations, such as intersections and roadway segments that exhibit an unusually high number of expected collisions or an abnormally high proportion of a certain configuration of collisions. Current state-of-the-art network screening methods rely on safety performance functions (SPFs) that require traffic volume as an input, but many cities in North America, including the city of Saskatoon, do not collect traffic volume for every intersection and segment within the city limits. Lack of traffic volume data severely restricts the applicability of a SPF-based network screening method. The binomial and beta-binomial tests, however, are formal collision diagnosis tests that can be used as a supplementary tool for screening roadway networks that include roadway segments for which traffic volume data are not available. However, previous studies have applied these two collision diagnosis tests without explicitly defining the particular circumstances that indicate which test is preferable. This study introduces a formal statistical test known as the "C(α) test" to determine when there is a need to apply the beta-binomial test instead of the binomial test to screen a roadway network. The study targeted major arterial uncontrolled access segments in Saskatoon using five years (2005-2009) of collision data for the two most frequent collision configurations: (1) rear end, and (2) side swipe same direction collisions. ArcGIS was used to develop collision maps that visually display the screening results. The collision maps are designed to facilitate the governing agencies' decision-making processes when selecting appropriate safety countermeasures to reduce target collision configurations at screened locations.
authors.affiliation: Department of Civil and Geological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9, Canada. peter.park@usask.ca
authors.forename: Peter Y
authors.initials: PY
authors.lastname: Park
authors.forename: Rajib
authors.initials: R
authors.lastname: Sahaji
mesh_terms: D000063:Accidents, Traffic / Q000517:prevention & control* / Q000706:statistics & numerical data; D016208:Databases, Factual; D040362:Geographic Information Systems; D006801:Humans; D008377:Maps as Topic; D015233:Models, Statistical; D012449:Safety; D012525:Saskatchewan; D014505:Urban Population