Study Details

Study Title: Safety effects of wider edge lines on rural, two-lane highways

Authors: Park et al.

Publication Date:SEP, 2012

Abstract: Although it is generally expected that wider lines will have a positive effect on vehicle safety, there have not been any convincing evidence based on the crash data analysis, partly because of the lack of relevant data. In this paper, the safety effect of wider edge lines was examined by analyzing crash frequency data for road segments with and without wider edge lines. The data from three states, Kansas, Michigan, and Illinois, have been analyzed. Because of different nature of data from each state, a different statistical analysis approach was employed for each state: an empirical Bayes, before-after analysis of Kansas data, an interrupted time series design and generalized linear segmented regression analysis of Michigan data, and a cross sectional analysis of Illinois data. Although it is well-known that causation is hard to establish based on observational studies, the results from three extensive statistical analyses all point to the same findings. The consistent findings lend support to the positive safety effects of wider edge lines installed on rural, two-lane highways.

Study Citation: Park, E.S., P.J. Carlson, R.J. Porter, and C.K. Anderson. "Safety effects of wider edge lines on rural, two-lane highways". Accident Analysis and Prevention Vol. 48, (2012) pp. 317-325. Interim results (not included in the CMF Clearinghouse) were published in a TTI report (Miles, D.M., Carlson, P.J., Eurek, R., Re, J., and Park, E.S., "Evaluation of Potential Benefits of Wider and Brighter Edge Line Pavement Markings." FHWA/TX-10/0-5862-1 Texas Transportation Institute, Texas Department of Transportation, July 2010.) Additionally, these findings will be published (TBD) in a final report for FHWA.


CMFs Associated With This Study

Category: Delineation

Countermeasure: Install wider edgelines (4 in to 5 in)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.62337.73 StarsAllK,A,B,CNot specifiedRural
0.76123.93 StarsAllONot specifiedRural
0.70929.13 StarsDay timeAllNot specifiedRural
0.70129.93 StarsNighttimeAllNot specifiedRural
0.64363 StarsDay timeK,A,B,CNot specifiedRural
0.65334.73 StarsWet roadAllNot specifiedRural
0.65834.23 StarsNighttimeK,A,B,CNot specifiedRural
0.69930.13 StarsAllAllNot specifiedRural
0.64335.73 StarsNighttime,Wet roadAllNot specifiedRural
0.63373 StarsSingle vehicleAllNot specifiedRural
0.67232.83 StarsSingle vehicle,Wet roadAllNot specifiedRural
0.70529.53 StarsNighttime,Single vehicleAllNot specifiedRural
0.57842.23 StarsSingle vehicleK,A,B,CNot specifiedRural
0.75924.13 StarsOtherAllNot specifiedRural
0.70529.53 StarsFixed objectAllNot specifiedRural
0.63736.33 StarsNighttime,Single vehicleK,A,B,CNot specifiedRural

Countermeasure: Install wider edgelines (4 in to 6 in)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.73274 StarsSingle vehicleAllNot specifiedRural
0.63236.83 StarsSingle vehicleK,A,B,CNot specifiedRural
0.81618.43 StarsNighttime,Single vehicleAllNot specifiedRural
0.81318.73 StarsNighttime,Single vehicleK,A,B,CNot specifiedRural
0.81193 StarsFixed objectAllNot specifiedRural
0.58541.53 StarsDay timeK,A,B,CNot specifiedRural
0.82517.54 StarsAllAllNot specifiedRural
0.63536.54 StarsAllK,A,B,CNot specifiedRural
0.87712.34 StarsAllONot specifiedRural
0.71428.64 StarsDay timeAllNot specifiedRural
0.9623.83 StarsNighttimeAllNot specifiedRural
0.87312.73 StarsNighttimeK,A,B,CNot specifiedRural
0.77122.93 StarsWet roadAllNot specifiedRural
0.80619.43 StarsAllAllNot specifiedRural
0.83916.13 StarsAllK,A,B,CNot specifiedRural
0.80419.63 StarsAllONot specifiedRural
0.75724.33 StarsNighttime,Wet roadAllNot specifiedRural
0.81218.83 StarsNighttimeAllNot specifiedRural
0.77233 StarsDay timeK,A,B,CNot specifiedRural
1.058-5.83 StarsNighttimeK,A,B,CNot specifiedRural
0.37462.63 StarsWet roadAllNot specifiedRural
0.88123 StarsDay timeAllNot specifiedRural
0.81318.73 StarsSingle vehicleAllNot specifiedRural
0.34165.93 StarsSingle vehicle,Wet roadAllNot specifiedRural
0.82183 StarsNighttime,Single vehicleAllNot specifiedRural
1.019-1.93 StarsSingle vehicleK,A,B,CNot specifiedRural
0.20879.23 StarsNighttime,Wet roadAllNot specifiedRural