Study Details
Study Title: Estimating Crash Modification Factors Using Cross-Sectional and Case-Control Methods for Rumble Strips and Paved Shoulders
Authors: Galgamuwa and Dissanayake
Publication Date:JAN, 2017
Abstract: This paper describes the application of case-control and cross-sectional methods to develop crash modification factors (CMFs) for lane departure countermeasures in two-lane rural undivided road segments in Kansas. Four commonly used countermeasures, namely 2-ft paved shoulders, centerline rumble strips, shoulder rumble strips, and shoulder & centerline rumble strips have been considered. CMFs were calculated for all severity and fatal & injury lane departure crashes. Generalized linear regression assuming a negative binomial error structure and logistic regression were used in developing models for cross-sectional and case-control methods respectively. Mean residuals and mean squared error (MSE) were used to validate the models developed for cross-sectional method. Classification tables were used to validate the models developed for case-control method. Cross-sectional method shows that all the countermeasures considered in this study were effective in reducing all severity and fatal & injury lane departure crashes. However, the range of CMF includes 1, for the shoulder rumble strips on curved road segments for all crash severities, which indicates that it has some crash increasing effect. The case-control study also shows that all the countermeasures have a crash reduction effect except shoulder rumble strips on curved road segments for all crash severities. Even though similar results were obtained from both methods, CMFs developed using the cross-sectional method demonstrated a narrower range than the case-control method indicating that the results from the cross-sectional method can be considered as more accurate and reliable than those from case control method.
Study Citation: Galgamuwa, U., and S. Dissanayake. "Estimating Crash Modification Factors Using Cross-Sectional and Case-Control Methods for Rumble Strips and Paved Shoulders". Presented at the 96th Annual Meeting of the Transportation Research Board, Paper No. 17-01474, Washington, D.C., (2017).
CMFs Associated With This Study
Category: Roadway
Countermeasure: Install centerline and shoulder rumble strips
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.86 | 14 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.94 | 6 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
0.89 | 11 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.87 | 13 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
Countermeasure: Install centerline rumble strips on horizontal curves
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.94 | 6 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.95 | 5 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
Countermeasure: Install centerline rumble strips on tangent sections
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.96 | 4 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.96 | 4 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
Category:Shoulder treatments
Countermeasure: Install shoulder rumble strips (horizontal curves)
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.95 | 5 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.94 | 6 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
Countermeasure: Install shoulder rumble strips (tangents)
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.94 | 6 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.95 | 5 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
Countermeasure: Provide 2-ft paved shoulders (both sides)
CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.88 | 12 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.94 | 6 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |
0.89 | 11 | | Head on,Run off road,Sideswipe | All | Not specified | Rural |
0.93 | 7 | | Head on,Run off road,Sideswipe | K,A,B,C | Not specified | Rural |