Study Details

Study Title: Comparison of Safety Evaluation Approaches for Intersection Signalization in Florida

Authors: Wang and Abdel-Aty

Publication Date:JAN, 2014

Abstract: In this study, we evaluate the safety effectiveness of introducing traffic signals to stop controlled intersections. According to the Highway Safety Manual (HSM), various Crash Modification Factors (CMFs) have been identified to predict safety performance after updating a stop to a signal controlled intersection. Different CMFs may be expected for the same treatment under different circumstances. Therefore, one CMF may not be able to represent the safety performance under all settings. This paper presents CMFs for signalization and attempts to investigate the relationship between CMF and Annual Average Daily Traffic (AADT). CMFs are examined at different ranges of AADT. According to the 2009 Manual on Uniform Traffic Control Devices (MUTCD), signalizing a stop controlled intersection would be expected to have positive effects on the safety performance. This assumption needs to be proven under different intersection configurations. Our study focuses on grouping intersections into five AADT levels and comparing the safety performance of these levels. In addition, the effects on total crashes and severe crashes (fatal and injury crashes) are analyzed separately; two Safety Performance Functions (SPFs) are estimated, one for total and the other is for fatal and injury crashes. After calculating CMFs based on the Empirical Bayes (EB) method, the result points out that potential risk may occur when the AADT of the target intersections are between 20,000-25,000 vpd for total crashes and 20,000-35000 for fatal and injury (F+I) crashes. Therefore, based on this result, it is suggested that the MUTCD signalization warrant could consider AADT levels and other considerations when making the signalization decision.

Study Citation: Wang, J.H. and M.A. Abdel-Aty. "Comparison of Safety Evaluation Approaches for Intersection Signalization in Florida". Presented at the 93rd Annual Meeting of the Transportation Research Board, Paper No. 14-0374, Washington, D.C., (2014)

CMFs Associated With This Study

Category: Intersection traffic control

Countermeasure: Install a traffic signal

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.65634.42 StarsAllAllNot specifiedNot specified
0.60439.62 StarsAllK,A,B,CNot specifiedNot specified
0.50249.82 StarsAllAllNot specifiedNot specified
0.40259.82 StarsAllK,A,B,CNot specifiedNot specified
1.119-11.92 StarsAllAllNot specifiedNot specified
1.184-18.42 StarsAllK,A,B,CNot specifiedNot specified
0.76243 StarsAllAllNot specifiedNot specified
0.79120.92 StarsAllK,A,B,CNot specifiedNot specified
0.76823.23 StarsAllAllNot specifiedNot specified
0.68431.63 StarsAllK,A,B,CNot specifiedNot specified