CRASH MODIFICATION FACTORS CLEARINGHOUSE

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
			All	K,A,B,C	Principal Arterial Interstate

Run off road

K,A,B,C

Principal Arterial Interstate

All

K,A,B,C

Principal Arterial Interstate

Wet road

K,A,B,C

Principal Arterial Interstate

Run off road

K,A,B,C

Principal Arterial Interstate

Run off road,Wet road

K,A,B,C

Principal Arterial Interstate

All

K,A,B,C

Principal Arterial Interstate

Wet road

K,A,B,C

Principal Arterial Interstate

Run off road

K,A,B,C

Principal Arterial Interstate

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
			All	K,A,B,C	All

Wet road

K,A,B,C

All

Run off road

K,A,B,C

All

Run off road,Wet road

K,A,B,C

All

All

K,A,B,C

All

Run off road

K,A,B,C

All

Run off road

K,A,B,C

All

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
			All	K,A,B,C	All	Not specified

Wet road

K,A,B,C

All

Not specified

Run off road

K,A,B,C

All

Not specified

Run off road,Wet road

K,A,B,C

All

Not specified

All

K,A,B,C

All

Wet road

K,A,B,C

All

Run off road

K,A,B,C

All

Run off road,Wet road

K,A,B,C

All

All

K,A,B,C

All

Wet road

K,A,B,C

All

Run off road

K,A,B,C

All

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
			All	K,A,B,C	All

Run off road

K,A,B,C

All

All

K,A,B,C

All

Wet road

K,A,B,C

All

Run off road

K,A,B,C

All

Run off road,Wet road

K,A,B,C

All

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For more information, contact Matt Hinshaw at matthew.hinshaw@dot.gov