01590402

Component

Transportation planners and traffic engineers are increasingly turning to crash reduction factors to evaluate changes in road geometric and design features in order to reduce crashes. Crash reduction factors are typically estimated based on segmenting a highway, to associated crashes with geometric features; this allows statistical methods to be applied to the data. Concurrently there is a stream of research that relies on spatial units of analysis to examine crashes; these typically use broad features of the road network combined with socio-economic and demographic factors that are associated with crashes. In this paper, the authors examine whether omission of these other factors in a link-based geometric results in omitted variable bias. The results suggest that there is no change in coefficient signs, but that there is a reduction in the magnitude of estimates. The sign of spatial variables, however, is quite different when combined into a link-based model. The authors also find substantial variability in coefficient estimates, and discuss the implications of these results for the use of crash reduction factors.

This paper was sponsored by TRB committee ANB20 Standing Committee on Safety Data, Analysis and Evaluation.

01584066

16-4150

English

19p

2016

Transportation Research Board 95th Annual Meeting

Web

References (35) ; Tables

Crash characteristics; Geometric segments; Highway design; Highway safety; Risk management; Spatial analysis

Highways; Safety and Human Factors; I82: Accidents and Transport Infrastructure; I85: Safety Devices used in Transport Infrastructure

Transportation Research Board Annual Meeting 2016 Paper #16-4150

TRIS, TRB, ATRI

Jan 12 2016 5:50PM