Important omitted spatial variables in safety models: Understanding contributing crash causes at intersections

Mitra, Sudeshna, Washington, Simon, & van Schalkwyk, Ida (2007) Important omitted spatial variables in safety models: Understanding contributing crash causes at intersections. In Meyer, M (Ed.) Transportation Research Board 86th Annual Meeting 2007 Compendium of Papers, Transportation Research Board of the National Academies, Washington, D.C., pp. 1-32.

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Advances in safety research—trying to improve the collective understanding of motor vehicle crash causation—rests upon the pursuit of numerous lines of inquiry. The research community has focused on analytical methods development (negative binomial specifications, simultaneous equations, etc.), on better experimental designs (before-after studies, comparison sites, etc.), on improving exposure measures, and on model specification improvements (additive terms, non-linear relations, etc.). One might think of different lines of inquiry in terms of ‘low lying fruit’—areas of inquiry that might provide significant improvements in understanding crash causation. It is the contention of this research that omitted variable bias caused by the exclusion of important variables is an important line of inquiry in safety research. In particular, spatially related variables are often difficult to collect and omitted from crash models—but offer significant ability to better understand contributing factors to crashes. This study—believed to represent a unique contribution to the safety literature—develops and examines the role of a sizeable set of spatial variables in intersection crash occurrence. In addition to commonly considered traffic and geometric variables, examined spatial factors include local influences of weather, sun glare, proximity to drinking establishments, and proximity to schools. The results indicate that inclusion of these factors results in significant improvement in model explanatory power, and the results also generally agree with expectation. The research illuminates the importance of spatial variables in safety research and also the negative consequences of their omissions.

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ID Code: 38167
Item Type: Conference Paper
Refereed: Yes
Keywords: Accident analysis, Accident causes, Accident prone locations, Cost effectiveness, Cyclists, Glare, Intersections, Mathematical models, Pedestrians, Schools, Spatial analysis
Subjects: Australian and New Zealand Standard Research Classification > BUILT ENVIRONMENT AND DESIGN (120000) > URBAN AND REGIONAL PLANNING (120500)
Divisions: Current > Research Centres > Centre for Accident Research & Road Safety - Qld (CARRS-Q)
Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Deposited On: 27 Oct 2010 01:09
Last Modified: 22 Jun 2017 23:40

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