Study Details
Study Title: Safety Evaluation of Converting Traffic Signals from Incandescent to LED Bulbs
Authors: Srinivasan et al.
Publication Date: JAN, 2013
Abstract: Data from 282 signalized intersections in Charlotte were used to examine the safety effect of converting the signals to composite light emitting diode (LED) bulbs. An empirical Bayes before-after method was used for the evaluation. Since this was a "blanket" installation by the city of Charlotte, a comparison group of stop controlled intersections were used to account for possible trends during the study period. Crash modification factors were estimated for 3 and 4 leg intersections for 8 different crash types including crashes during dawn, dusk, and dark conditions. For 3 leg intersections, all the CMFs were higher than 1.0 indicating a possible increase in crashes due to LEDs. However, none of these CMFs were statistically different from 1.0 at the 0.05 significance level. For 4 leg intersections, the CMFs associated with rear-end crashes were lower than 1.0 and statistically significant at the 0.05 level, indicating a reduction in these crash types due to the LEDs. There was substantial difference among the sites in terms of the effect of the LEDs. The reasons for these differences are not known at this time. Future research could investigate whether LEDs are more or less beneficial depending on the characteristics of the intersection including type of area, sight distance, traffic volume, and phasing scheme.
Study Citation: Srinivasan, R.; Carter, D.; Smith, S.; and Lan B. "Safety Evaluation of Converting Traffic Signals from Incandescent to LED Bulbs" Presented at the Transportation Research Board 92nd Annual Meeting, Paper No. 13-1373, Washington, D.C. (January 2013).
Related Citations: Srinivasan, R.; Carter, D.; Smith, S.; and Lan B. "Safety Evaluation of Converting Traffic Signals from Incandescent to Light-Emitting Diodes", Federal Highway Administration, Highway Safety Information System Summary Report, FHWA-HRT-13-070, HRDS-20/08-13(750)E (August 2013).
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Intersection traffic control
Countermeasure: Replace Incandescent Traffic Signal Bulbs with Light Emitting Diodes (LEDs)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|
| 1.042 | -4.2 |  | All | All | Not specified | Urban |
| 1.17 | -17 | | All | K,A,B,C | Not specified | Urban |
| 1.016 | -1.6 | | Angle,Head on,Left turn | All | Not specified | Urban |
| 1.078 | -7.8 | | Angle,Head on,Left turn | All | Not specified | Urban |
| 1.091 | -9.1 |  | Angle,Head on,Left turn | All | Not specified | Urban |
| 0.959 | 4.1 | | Angle,Head on,Left turn | All | Not specified | Urban |
