CTRE is an Iowa State University center, administered by the Institute for Transportation.

Address: 2711 S. Loop Drive, Suite 4700, Ames, IA 50010-8664

Phone: 515-294-8103
FAX: 515-294-0467

Website: www.ctre.iastate.edu/

Iowa State University--Becoming the Best

Estimating Crash Modification Factors for Lane Departure Countermeasures in Kansas

Researcher(s)

Principal investigator:

Co-principal investigators:

Project status

Completed

Start date: 08/15/15
End date: 12/29/17

Publications

Report: Estimating Crash Modification Factors for Lane Departure Countermeasures in Kansas (1.74 mb pdf) December 2017

Related publications:

Sponsor(s)/partner(s)

Sponsor(s):

About the research

Abstract:

This project was conducted to estimate crash modification factors (CMFs) for lane departure countermeasures in Kansas. Cross-sectional, case-control, and before-and-after empirical Bayes (EB) methods were employed. Results showed that centerline rumble strips on rural two-lane road segments have crash-reduction effects on all lane departure and fatal and injury lane departure crashes on both tangent and curved road segments. Shoulder rumble strips were effective in reducing all lane departure and fatal and injury lane departure crashes on tangent road segments but showed less effectiveness on curved road segments. The combination of centerline and shoulder rumble strips showed significant safety effectiveness on both tangent and curved road segments.

Shoulder rumble strips on four-lane road segments also showed crash-reduction effects on all lane departure and fatal and injury lane departure crashes on both tangent and curved road segments. Cable median barriers showed a crash-reduction effect on all lane departure crashes, and fatal and injury lane departure crashes on four-lane divided road segments. Chevrons and post-mounted delineators also showed effectiveness on both all lane departure crashes and fatal and injury lane departure crashes. The safety edge treatment also showed a crash-reduction effect on all lane departure crashes and fatal and injury lane departure crashes.

Finally, all models were validated to check for accuracy. Models developed for the cross-sectional method were validated using mean square error and mean of the residuals. Case-control models were validated using the specificity, accuracy, and sensitivity of the models. The significance of the CMFs developed using the before-and-after EB method was realized using the method given in the Highway Safety Manual.