Study Details
Study Title: Development of Crash Modification Factors for Bicycle Lane Additions While Reducing Lane and Shoulder Widths
Authors:
Publication Date: 2021
Abstract: This project evaluated bicycle lane additions when reducing lane and shoulder width as a safety improvement strategy (safety intervention). Crash modification factors (CMFs) and benefit-to-cost ratios (B/C) were estimated for total, fatal and injury, and property-damage-only (PDO) crashes. Studied facilities included urban two-lane and four-lane arterials, collectors, and local roads in Washington and Texas. The study design was cross-sectional, including sites without bicycle lanes but with similar characteristics to sites with bicycle lanes. The research team applied propensity score methods both on data collection and in statistical analyses to improve the balance between treated and comparison sites. The results for Washington suggested reductions for fatal and injury (0.772 CMF, statistically insignificant) and PDO crashes (0.885 CMF, statistically insignificant) but the small sample size resulted in large uncertainties for these estimates.
The results for Texas were consistent with the directions and magnitudes of the Washington analysis. In contrast, the larger dataset from Texas yielded CMF estimates with statistical significance at the 95 percent confidence level. From the Texas analysis this research found statistically significant CMFs for total and for PDO crashes ranged between 0.435 and 0.734, depending on facility type and bicycle volumes. All CMFs for fatal and injury crashes were statistically insignificant (CMFs ranging between 0.643 and 1.28 depending on facility type) as well as some CMFs for total crashes (ranging from 0.558 and 0.975, all statistically insignificant). The B/C ratio estimated for Texas two-lane undivided urban collectors and local streets was 16.61, assuming the average daily bicycle traffic does not increase after the installation of bicycle lanes.
Study Citation: Avelar, R., K. Dixon, S. Ashraf, A, Jhamb, and B. Dadashova. "Development of Crash Modification Factors for Bicycle Lane Additions While Reducing Lane and Shoulder Widths" Report No. FHWA-HRT-21-013. Federal Highway Administration, Office of Safety Research and Development. McLean, Virginia. (2021).
Related Citations: Tech Brief. "Development of Crash Modification Factors for Bicycle Lane Additions While Reducing Lane and Shoulder Widths" Report No. FHWA-HRT-21-012. Federal Highway Administration, Office of Safety Research and Development. McLean, Virginia. (2021).
CMFs Associated With This Study
Category: Bicyclists
Countermeasure: Install bicycle lanes
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|
| 0.7859 | 21.41 |  | All | All | All | Urban |
