Safety Performance Of Combinations Of Traffic And Roadway Cross-Sectional Design Elements At Straight And Curved Segments
Keywords
Crash modification factors; Cross-sectional method; Generalized nonlinear models; Shoulder and lane widths; Traffic volume
Abstract
This study develops various crash modification factors (CMFs) for combinations of traffic and roadway cross-sectional elements at noncurved (i.e., straight) and curved roadway sections using the cross-sectional method. Generally, a CMF estimates the expected changes in crash frequency after a single specific treatment is implemented on a roadway. The results indicate that increasing lane width, increasing shoulder width, and their combination are safety effective in reducing crash frequency in general. In particular, it was found that crash frequency decreases as the lane width increases until 3.51 m (11.5 ft) width and it increases as the lane width exceeds 3.51 m. The crash rates start to decrease again after 3.81 m (12.5 ft). The results also indicate that the developed nonlinearizing link function derived nonlinear relationship between crash rates and lane width, and this relationship was clearly reflected in the generalized nonlinear models (GNMs). Moreover, there is a significant interaction impact between lane and shoulder widths at segments with a horizontal curve whereas the interaction term is not significant at noncurved segments. It was also found that the CMFs for increasing lane and shoulder widths are decreasing as annual average daily traffic (AADT) level increases. Based on the findings from this study, it is recommended to apply the proposed methodology of utilizing the GNMs with interaction terms in the cross-sectional method to (1) estimate more accurate CMFs for single treatments and combinations of treatments and (2) reflect the nonlinearity of crash predictors and interaction impacts among variables.
Publication Date
6-1-2017
Publication Title
Journal of Transportation Engineering
Volume
143
Issue
6
Document Type
Article
Personal Identifier
scopus
DOI Link
https://doi.org/10.1061/JTEPBS.0000033
Copyright Status
Unknown
Socpus ID
85017501859 (Scopus)
Source API URL
https://api.elsevier.com/content/abstract/scopus_id/85017501859
STARS Citation
Park, Juneyoung and Abdel-Aty, Mohamed, "Safety Performance Of Combinations Of Traffic And Roadway Cross-Sectional Design Elements At Straight And Curved Segments" (2017). Scopus Export 2015-2019. 4862.
https://stars.library.ucf.edu/scopus2015/4862