Study Details

Study Title: Evaluating the Need for Surface Treatments to Reduce Crash Frequency on Horizontal Curves

Authors: Pratt et al.

Publication Date: MAY, 2014

Abstract: The application of high-friction surface treatments at appropriate horizontal curve locations throughout the state has the potential to improve driver performance and reduce the number of crashes experienced at horizontal curves. These treatments must be implemented judiciously due to their cost, but have the potential to improve safety at lower cost than geometric improvements like curve straightening, and with greater effectiveness than control-device treatments like installing delineators or Chevrons. An analysis framework has been developed to assess the need for surface treatments at curves based on the concept of margin of safety analysis. Models have been developed to predict vehicle speeds throughout a curve, and calibrated using data from Texas curve sites. Safety prediction models have also been developed to quantify the relationship between skid number and curve crash frequency. This information can be applied to evaluate the safety performance of a curve of interest and estimate the potential safety benefit of installing a high-friction surface treatment.

Study Citation: Pratt, M.P, S. R. Geedipally, A. M. Pike, P. J. Carlson, A. M .Celoza, and D. Lord. " Evaluating the Need for Surface Treatments to Reduce Crash Frequency on Horizontal Curves." Report No. FHWA/TX-14/0-6714-1. Texas Department of Transportation. Austin, Texas. (May 2014)

Study Report: Download the Study Report Document


CMFs Associated With This Study

Category: Alignment

Countermeasure: Change horizontal curve radius from straight tangent to radius of R feet (at speed limit of V in mph)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation 3 Stars All K,A,B,C Principal Arterial Interstate
CMF Equation 3 Stars Run off road K,A,B,C Principal Arterial Interstate
CMF Equation 3 Stars All K,A,B,C Principal Arterial Interstate
CMF Equation 2 Stars Wet road K,A,B,C Principal Arterial Interstate
CMF Equation 3 Stars Run off road K,A,B,C Principal Arterial Interstate
CMF Equation 2 Stars Run off road,Wet road K,A,B,C Principal Arterial Interstate
CMF Equation 3 Stars All K,A,B,C Principal Arterial Interstate
CMF Equation 3 Stars Wet road K,A,B,C Principal Arterial Interstate
CMF Equation 3 Stars Run off road K,A,B,C Principal Arterial Interstate
CMF Equation 2 Stars Run off road,Wet road K,A,B,C Principal Arterial Interstate

Category:Roadway

Countermeasure: Change lane width from 12 ft to LW (in feet)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation 3 Stars All K,A,B,C All
CMF Equation 3 Stars Wet road K,A,B,C All
CMF Equation 3 Stars Run off road K,A,B,C All
CMF Equation 3 Stars Run off road,Wet road K,A,B,C All
CMF Equation 3 Stars All K,A,B,C All
CMF Equation 2 Stars Run off road K,A,B,C All
CMF Equation 3 Stars Run off road K,A,B,C All
CMF Equation 2 Stars Run off road,Wet road K,A,B,C All

Countermeasure: Change pavement friction from 40 to SK (in friction number)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation 3 Stars All K,A,B,C All Not specified
CMF Equation 3 Stars Wet road K,A,B,C All Not specified
CMF Equation 3 Stars Run off road K,A,B,C All Not specified
CMF Equation 3 Stars Run off road,Wet road K,A,B,C All Not specified
CMF Equation 3 Stars All K,A,B,C All
CMF Equation 2 Stars Wet road K,A,B,C All
CMF Equation 2 Stars Run off road K,A,B,C All
CMF Equation 2 Stars Run off road,Wet road K,A,B,C All
CMF Equation 3 Stars All K,A,B,C All
CMF Equation 3 Stars Wet road K,A,B,C All
CMF Equation 3 Stars Run off road K,A,B,C All
CMF Equation 3 Stars Run off road,Wet road K,A,B,C All

Category:Shoulder treatments

Countermeasure: Change shoulder width from 8 ft to SW (in feet)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
CMF Equation 3 Stars All K,A,B,C All
CMF Equation 3 Stars Run off road K,A,B,C All
CMF Equation 3 Stars All K,A,B,C All
CMF Equation 3 Stars Wet road K,A,B,C All
CMF Equation 3 Stars Run off road K,A,B,C All
CMF Equation 2 Stars Run off road,Wet road K,A,B,C All

The information contained in the Crash Modification Factors (CMF) Clearinghouse is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in the CMF Clearinghouse. The information contained in the CMF Clearinghouse does not constitute a standard, specification, or regulation, nor is it a substitute for sound engineering judgment.