Study Details

Study Title: Safety Impact of Cable Barriers on Rural Interstates

Authors: Villwock et al.

Publication Date:JAN, 2009

Abstract: High-tensioned cable barriers have only recently been introduced in the United States as a median barrier option, primarily as a result of state agencies looking for a cost-effective means with which to mitigate or eliminate cross-median crashes. Few studies, however, provide a means with which to estimate the frequency and severity of a roadway segment with cable barriers. A combination of a before-and-after analysis with negative binomial and logistic regression was applied to data obtained from eight states to investigate the impact of cable barriers on the frequency and severity of crashes on a roadway segment. Three types of crashes were investigated for both the frequency and severity of crashes: single vehicle, multiple-vehicle same-direction, and multiple-vehicle opposite-direction, also called cross-median or cross-over crashes. These three crash categories were considered separately with the assumption (confirmed with the results) that they are affected by the presence of the median barrier differently. The results indicate that an installation of cable barriers, both low and high-tensioned, eliminates more than 90% of multiple vehicle opposite direction crashes. The before-and-after analysis showed that this median treatment results in an increase in single vehicle crashes by about 80% and a weak if any effect on the frequency of multiple vehicle-same direction crashes. Considering severity, the proportion of severe crashes, in general, decreases by 8% with the installation of a low tensioned cable barrier. The effect of high-tensioned cables on severity measured with the proportion of injury and fatal crashes seems to be negligible.

Study Citation: Villwock, N., N. Blond, and A.P. Tarko, "Safety Impact of Cable Barriers on Rural Interstates." TRB 88th Annual Meeting Compendium of Papers CD-ROM. Washington, D.C., (2009).


CMFs Associated With This Study

Category: Roadside

Countermeasure: Install cable median barrier (high tension)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
1.72-723 StarsFixed object,Run off road,Single vehicleAllPrincipal Arterial InterstateRural
1.08-83 StarsRear end,SideswipeAllPrincipal Arterial InterstateRural
0.04963 StarsCross median,Frontal and opposing direction sideswipe,Head onAllPrincipal Arterial InterstateRural

Countermeasure: Install cable median barrier (low or high tension on curve)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.06944 StarsCross median,Frontal and opposing direction sideswipe,Head onAllPrincipal Arterial InterstateRural

Countermeasure: Install cable median barrier (low or high tension on tangent)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
01003 StarsCross median,Frontal and opposing direction sideswipe,Head onAllPrincipal Arterial InterstateRural

Countermeasure: Install cable median barrier (low or high tension)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
1.83-833 StarsFixed object,Run off road,Single vehicleAllPrincipal Arterial InterstateRural
0.86143 StarsRear end,SideswipeAllPrincipal Arterial InterstateRural
0.09913 StarsCross median,Frontal and opposing direction sideswipe,Head onAllPrincipal Arterial InterstateRural

Countermeasure: Install cable median barrier (low tension)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.75253 StarsFixed object,Run off road,Single vehicleAllPrincipal Arterial InterstateRural
1.87-873 StarsFixed object,Run off road,Single vehicleAllPrincipal Arterial InterstateRural
0.74263 StarsRear end,SideswipeAllPrincipal Arterial InterstateRural
0.78223 StarsRear end,SideswipeAllPrincipal Arterial InterstateNot specified