Study Details
Study Title: Safety Evaluation of Discontinuing Late Night Flash Operations at Signalized Intersections
Authors: Lan and Srinivasan
Publication Date:JAN, 2013
Abstract: This study examined the safety impacts of converting late nighttime flash (LNF) to normal phasing operation at signalized intersections using the empirical Bayes (EB), the univariate Full Bayesian (FB), and multivariate FB before-after methods. Data were obtained from the North Carolina Department of Transportation for 61 treatment sites and 395 reference intersections that remained on LNF operation from 2000 to 2007. The results from the EB method are almost identical to those of the univariate FB. The FB method offered more flexibility in selecting the functional form of expected crashes at similar sites (similar to the SPF in the EB), and addressing uncertainty in the data. Compared to the univariate FB, the multivariate FB using the multivariate poisson lognormal model (MVPLN) provided better results based on much lower deviance information criterion (DIC) values. The MVPLN model was favored and the recommended CRFs are 48% (plus or minus 6%), 53% (plus or minus 8%), and 57% (plus or minus 7%) for nighttime total, injury and fatal, and frontal impact crashes, respectively.
Study Citation: Lan, B. and Srinivasan R. "Safety Evaluation of Discontinuing Late Night Flash Operations at Signalized Intersections" Presented at the Transportation Research Board 92nd Annual Meeting, Paper No. 13-0988, January 13-17, 2013, Washington, DC.
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Intersection traffic control
Countermeasure: Replace Night-Time Flash with Steady Operation
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 0.52 | 48 |  | All | All | All | All |
| 0.47 | 53 | | All | K,A,B,C | All | All |
| 0.43 | 57 | | Angle,Head on,Left turn,Sideswipe | All | All | All |
