Study Details
Study Title: Effect of Horizontal Curves on Urban Arterial Crashes
Authors: Banihashemi
Publication Date: 2016
Abstract: The Highway Safety Manual (HSM) crash prediction models estimate the expected number of crashes for different facility types. Models in Part C Chapter 12 of the first edition of the HSM include crash prediction models for divided and undivided urban arterials. Each of the HSM crash prediction models for highway segments is comprised of a "Safety Performance Function," a function of AADT and segment length, plus, a series of "Crash Modification Factors" (CMFs). The SPF estimates the expected number of crashes for the site if the site features are of base condition. The effects of the other features of the site, if their values are different from base condition, are carried out through use of CMFs. The existing models for urban arterials do not have any CMF for horizontal curvature. The goal of this research is to investigate if the horizontal alignment has any significant effect on crashes on any of these types of facilities and if so, to develop a CMF for this feature. Washington State cross sectional data from the Highway Safety Information System (HSIS) lab was used in this research. Data from 2007 t o 2009 was used to conduct the investigation. The 2010 data was used to validate the results. As the results showed, the horizontal curvature has significant safety effect on two-lane undivided urban arterials and using a CMF for horizontal curvature in the crash prediction model of this type of facility improves the prediction of crashes significantly, for both tangent and curve segments.
Study Citation: Banihashemi, M., "Effect of Horizontal Curves on Urban Arterial Crashes." Presented at the 95th Annual Meeting of the Transportation Research Board, Washington, D.C., (2016).
Related Citations: Banihashemi, Mohamadreza, Effect of horizontal curves on urban arterial crashes, Accident Analysis & Prevention, Volume 95, Pages 20-26, ISSN 0001-4575, (2016), http://dx.doi.org/10.1016/j.aap.2016.06.014.
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Alignment
Countermeasure: Change horizontal alignment
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
 |  | All | All | Principal Arterial Other | Urban |
