Study Details

Study Title: Safety Evaluation of Cross-Sectional Elements of Freeway Managed Lanes

Authors: Avelar and Fitzpatrick

Publication Date: 2018

Abstract: This paper investigated the safety implications of managed-lane cross-sectional elements. The objective of the Federal Highway Administration project was to investigate the relationship between crashes and buffer-separated manage lane dimensions. The results from several previous research studies have demonstrated that reductions in freeway lane width or shoulder width are associated with more crashes. A narrower managed-lane envelope width (i.e., left shoulder, managed lane, and buffer width combined) is also associated with more freeway crashes for crashes of all severity levels and for fatal and injury crashes as well. Wider envelopes are associated a reduction of 2.8 percent (in Texas) or 2.0 percent (in California) in total freeway crashes (all severities) for each additional foot of envelope width. In California, wider envelopes are associated with a reduction of 4.4 percent in managed-lane-related crashes (fatal and injury severity levels) for each additional foot of envelope width. The analysis was conducted on non-weaving managed-lane segments that included a single managed lane separated from the general-purpose lanes with a flush buffer area. The dataset included crashes on 128.0 miles in California (all 128.0 miles with flush buffers) and 60.4 miles in Texas (41.7 miles with pylon buffers and 18.7 miles with flush buffers). The California sites included freeways with three or four general-purpose lanes while the Texas freeways had three to five general-purpose lanes.

Study Citation: Avelar, R., and K. Fitzpatrick. "Safety Evaluation of Cross-Sectional Elements of Freeway Managed Lanes". Presented at the 97th Annual Meeting of the Transportation Research Board, Paper No. 18-00323, Washington, D.C., (2018).

Related Citations: Fitzpatrick, K., and R. Avelar. "Safety Implications of Managed Lane Cross Sectional Elements. Report No. FHWA-HOP-16-076. Federal Highway Administration. Washington, D.C. (December 2016).

Study Report: Download the Study Report Document

CMFs Associated With This Study

Category: Roadway

Countermeasure: Widen managed lane envelope

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.9824 StarsAllAllNot specifiedUrban and suburban
0.9823 StarsAllAllNot specifiedUrban and suburban
0.9564.43 StarsOtherK,A,B,CNot specifiedUrban and suburban