Study Details
Study Title: Safety Evaluation of the Safety Edge Treatment
Authors: Graham et al.
Publication Date:MAR, 2011
Abstract: Between periods of maintenance, pavement-edge drop-offs can form along the edge of highways. When a driver runs off the roadway, such drop-offs can hinder reentry and may lead to driver overcorrection, loss of control, or overturning on the roadway or roadside. The safety edge is a treatment that is implemented in conjunction with pavement resurfacing and is intended to help minimize drop-off-related crashes. This report examines the safety effects, costs, and benefits of this low-cost treatment for two-lane and multilane rural highways. The safety research was conducted as an observational before-after evaluation of treated sites using the empirical Bayes method. The economic appraisal consisted of a benefit-cost analysis. The safety evaluation found that the safety edge treatment appears to have a small positive crash reduction effect. The best effectiveness measure for the safety edge treatment was a 5.7 percent reduction in total crashes on rural two-lane highways. However, this result was not statistically significant. The economic analysis showed that the treatment is very inexpensive and that its application is highly cost-effective for a broad range of conditions on two-lane highways. Inconsistent results were found for rural multilane highways due to a small data sample.
Study Citation: Graham, J.L., Richard, K.R. , O'Laughlin, M.K., Harwood, D.W., "Safety Evaluation of the Safety Edge Treatment" Report No. FHWA-HRT-11-024, Federal Highway Administration, Washington, DC. (2011)
Study Report: Download the Study Report Document
CMFs Associated With This Study
Category: Shoulder treatments
Countermeasure: Install safety edge treatment
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 0.948 | 5.16 |  | Run off road | O | Principal Arterial Other | Rural |
| 0.798 | 20.225 | | Run off road | O | Principal Arterial Other | Rural |
| 0.885 | 11.524 | | Run off road | O | Principal Arterial Other | Rural |
| 1.035 | -3.538 | | Run off road | O | Principal Arterial Other | Rural |
| 1.312 | -31.229 | | Run off road | O | Principal Arterial Other | Rural |
| 1.129 | -12.878 | | Run off road | O | Principal Arterial Other | Rural |
| 0.926 | 7.374 | | Run off road | O | Principal Arterial Other | Rural |
| 0.84 | 16.029 |  | Run off road | O | Principal Arterial Other | Rural |
| 0.898 | 10.162 | | Run off road | O | Principal Arterial Other | Rural |
| 0.897 | 10.293 | | Other | All | Principal Arterial Other | Rural |
| 0.909 | 9.13 | | Other | All | Principal Arterial Other | Rural |
| 0.934 | 6.603 | | Other | All | Principal Arterial Other | Rural |
| 0.912 | 8.759 | | Other | All | Principal Arterial Other | Rural |
| 1.796 | -79.564 | | Other | All | Principal Arterial Other | Rural |
| 1.197 | -19.733 | | Other | All | Principal Arterial Other | Rural |
| 0.874 | 12.586 | | Other | All | Principal Arterial Other | Rural |
| 0.955 | 4.455 | | Other | All | Principal Arterial Other | Rural |
| 0.944 | 5.587 | | Other | All | Principal Arterial Other | Rural |
| 0.849 | 15.135 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 1.184 | -18.357 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 1.052 | -5.202 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 0.575 | 42.488 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 0.615 | 38.503 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 0.63 | 36.972 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 0.784 | 21.596 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 1.052 | -5.23 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 0.953 | 4.676 | | Other | K,A,B,C | Principal Arterial Other | Rural |
| 0.975 | 2.55 | | Other | O | Principal Arterial Other | Rural |
| 0.794 | 20.631 | | Other | O | Principal Arterial Other | Rural |
| 0.892 | 10.829 | | Other | O | Principal Arterial Other | Rural |
| 1.026 | -2.553 | | Other | O | Principal Arterial Other | Rural |
| 2.317 | -131.652 | | Other | O | Principal Arterial Other | Rural |
| 1.41 | -40.967 | | Other | O | Principal Arterial Other | Rural |
| 0.947 | 5.319 | | Other | O | Principal Arterial Other | Rural |
| 0.921 | 7.89 | | Other | O | Principal Arterial Other | Rural |
| 0.956 | 4.435 | | Other | O | Principal Arterial Other | Rural |
| 0.923 | 7.732 | | All | All | Principal Arterial Other | Rural |
| 0.886 | 11.361 | | All | All | Principal Arterial Other | Rural |
| 0.932 | 6.817 | | All | All | Principal Arterial Other | Rural |
| 0.845 | 15.524 | | All | All | Principal Arterial Other | Rural |
| 1.269 | -26.942 | | All | All | Principal Arterial Other | Rural |
| 1.002 | -0.235 | | All | All | Principal Arterial Other | Rural |
| 0.905 | 9.485 | | All | All | Principal Arterial Other | Rural |
| 0.935 | 6.516 | | All | All | Principal Arterial Other | Rural |
| 0.943 | 5.674 | | All | All | Principal Arterial Other | Rural |
| 0.89 | 10.959 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 1.156 | -15.555 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 1.06 | -5.982 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 0.55 | 44.993 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 0.565 | 43.548 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 0.591 | 40.939 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 0.835 | 16.528 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 1.064 | -6.361 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 0.983 | 1.667 | | All | K,A,B,C | Principal Arterial Other | Rural |
| 0.974 | 2.554 | | All | O | Principal Arterial Other | Rural |
| 0.757 | 24.281 | | All | O | Principal Arterial Other | Rural |
| 0.868 | 13.201 | | All | O | Principal Arterial Other | Rural |
| 0.934 | 6.579 | | All | O | Principal Arterial Other | Rural |
| 1.509 | -50.902 | | All | O | Principal Arterial Other | Rural |
| 1.129 | -12.894 | | All | O | Principal Arterial Other | Rural |
| 0.962 | 3.845 | | All | O | Principal Arterial Other | Rural |
| 0.872 | 12.795 | | All | O | Principal Arterial Other | Rural |
| 0.929 | 7.1 | | All | O | Principal Arterial Other | Rural |
| 0.863 | 13.721 | | Run off road | All | Principal Arterial Other | Rural |
| 0.909 | 9.08 | | Run off road | All | Principal Arterial Other | Rural |
| 0.921 | 7.872 | | Run off road | All | Principal Arterial Other | Rural |
| 0.918 | 8.183 | | Run off road | All | Principal Arterial Other | Rural |
| 1.469 | -46.895 | | Run off road | All | Principal Arterial Other | Rural |
| 1.135 | -13.484 | | Run off road | All | Principal Arterial Other | Rural |
| 0.858 | 14.177 | | Run off road | All | Principal Arterial Other | Rural |
| 0.952 | 4.786 | | Run off road | All | Principal Arterial Other | Rural |
| 0.937 | 6.315 | | Run off road | All | Principal Arterial Other | Rural |
| 0.808 | 19.175 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 1.181 | -18.058 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 1.036 | -3.609 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 0.537 | 46.332 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 1.125 | -12.464 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 0.836 | 16.402 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 0.769 | 23.123 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 1.2 | -20.037 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
| 1.026 | -2.622 | | Run off road | K,A,B,C | Principal Arterial Other | Rural |
