Study Details
Study Title: Development Of Crash Modification Factors For The Application Of The Safetyedge Treatment On Two-Lane Rural Roads
Authors: Donnell et al.
Publication Date:MAR, 2017
Abstract: This study estimated Crash Modification Factors (CMFs) for the SafetyEdgeSM paving technique on two-lane rural highways in Ohio, Iowa, and North Carolina. The SafetyEdgeSM provides a tapered roadway edge so that vehicles, on first incidence of experiencing a run-off-road event, can recover their trajectory more easily than more common pavement edges. The average angle of the SafetyEdgeSM was 31.8 degrees in Ohio, 29.7 degrees in Iowa, and 30.0 degrees in North Carolina. An empirical Bayes observational before-after evaluation found that the SafetyEdgeSM treatment was associated with statistically significant reductions in fatal and injury (FI), run-off-road (ROR), opposite direction (OPPDIR) including head-on and sideswipe, and drop-off-related crashes. A Crash Modification Function was calibrated to capture this relationship simultaneously with the variation of the CMF with other factors. An economic evaluation found that the SafetyEdgeSM paving technique is cost-effective, with the benefit-cost ratios ranging from 330 to 1,652 for ROR crashes, and from 409 to 2,044 for FI crashes. Finally, a pavement edge field data collection effort found that the reference group and SafetyEdgeSM treatment sites in North Carolina and Ohio often contained compacted backfill material, indicating traffic had not been exposed to the pavement edge, or shoulder maintenance had been performed recently. This is a good indication that the SafetyEdgeSM shape can hold backfill as well as the traditional shaped pavement edge. In Iowa, the field data collection effort showed that the backfill material was below the paved roadway surface, but the SafetyEdgeSM appeared to maintain its shape over time.
Study Citation: Donnell, E., C. Lyon, B. Persaud, F. Gross, and K. Eccles. "Development of Crash Modification Factors for the Application of the SafetyEdgeSM on Two-Lane Rural Roads". Federal Highway Administration, Washington, D.C. (March 2017).
CMFs Associated With This Study
Category: Shoulder treatments
Countermeasure: Install safety edge treatment
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.917 | 8.3 | | Run off road | All | Principal Arterial Other | Rural |
0.692 | 30.8 | | Run off road | All | Principal Arterial Other | Rural |
0.938 | 6.2 | | All | All | Principal Arterial Other | Rural |
1.07 | -7 | | All | All | Principal Arterial Other | Rural |
0.989 | 1.1 | | All | All | Principal Arterial Other | Rural |
0.842 | 15.8 | | All | K,A,B | Principal Arterial Other | Rural |
0.602 | 39.8 | | All | K,A,B | Principal Arterial Other | Rural |
0.986 | 1.4 | | All | K,A,B | Principal Arterial Other | Rural |
0.972 | 2.8 | | All | K,A,B | Principal Arterial Other | Rural |
0.343 | 65.7 | | All | K,A,B | Principal Arterial Other | Rural |
0.892 | 10.8 | | All | K,A,B | Principal Arterial Other | Rural |
0.724 | 27.6 | | Run off road | All | Principal Arterial Other | Rural |
1.016 | -1.6 | | Run off road | All | Principal Arterial Other | Rural |
0.969 | 3.1 | | Run off road | All | Principal Arterial Other | Rural |
0.764 | 23.6 | | Run off road | All | Principal Arterial Other | Rural |
0.115 | 88.5 | | Run off road | All | Principal Arterial Other | Rural |
0.79 | 21 | | Run off road | All | Principal Arterial Other | Rural |
0.68 | 32 | | Head on | All | Principal Arterial Other | Rural |
0.458 | 54.2 | | Head on | All | Principal Arterial Other | Rural |
0.751 | 24.9 | | Head on | All | Principal Arterial Other | Rural |
0.355 | 64.5 | | Head on | All | Principal Arterial Other | Rural |
0.813 | 18.7 | | Head on | All | Principal Arterial Other | Rural |
0.681 | 31.9 | | Other | All | Principal Arterial Other | Rural |
0.628 | 37.2 | | Other | All | Principal Arterial Other | Rural |
0.726 | 27.4 | | Other | All | Principal Arterial Other | Rural |
0.655 | 34.5 | | Other | All | Principal Arterial Other | Rural |
1.009 | -0.9 | | Run off road | All | Principal Arterial Other | Rural |
0.651 | 34.9 | | Run off road | All | Principal Arterial Other | Rural |
0.981 | 1.9 | | Run off road | All | Principal Arterial Other | Rural |
0.777 | 22.3 | | Run off road | All | Principal Arterial Other | Rural |
0.866 | 13.4 | | Run off road | All | Principal Arterial Other | Rural |
0.764 | 23.6 | | Run off road | All | Principal Arterial Other | Rural |
0.881 | 11.9 | | Run off road | All | Principal Arterial Other | Rural |
0.643 | 35.7 | | Run off road | All | Principal Arterial Other | Rural |
0.759 | 24.1 | | Run off road | All | Principal Arterial Other | Rural |
0.836 | 16.4 | | Run off road | All | Principal Arterial Other | Rural |
0.818 | 18.2 | | Run off road | All | Principal Arterial Other | Rural |
0.695 | 30.5 | | Run off road | All | Principal Arterial Other | Rural |