CMF / CRF Details

CMF ID: 4226

Decrease inside paved shoulder width from 4ft to 2ft (outside paved shoulder width = 10ft)

Description: Interchange influence area on urban four-lane freeway with a 2-ft inside paved shoulder and a 10-ft outside paved shoulder with warning device.

Prior Condition: 4-ft paved inside shoulder and 10-ft paved outside shoulder within interchange influence area

Category: Shoulder treatments

Study: Developing Crash Modification Factors for Interchange Influence Areas on Urban Four-Lane Freeways Using Multivariate Adaptive Regression Splines, Haleem, Gan, and Lu, 2012

Star Quality Rating: 3 Stars   [View score details]
Rating Points Total: 105
Crash Modification Factor (CMF)
Value: 0.668
Adjusted Standard Error:
Unadjusted Standard Error: 0.1
Crash Reduction Factor (CRF)
Value: 33.2   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 10
Crash Type: All
Crash Severity: All
Roadway Types: Principal Arterial Other Freeways and Expressways
Street Type:
Minimum Number of Lanes: 4
Maximum Number of Lanes: 4
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather: Not specified
Road Division Type: Divided by Median
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type: Urban
Traffic Volume:
Average Traffic Volume:
Time of Day: Not specified
If countermeasure is intersection-based
Intersection Type:
Intersection Geometry:
Traffic Control:
Major Road Traffic Volume:
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used: 2005 to 2008
State: FL
Country: United States
Type of Methodology Used: Regression cross-section
Sample Size (crashes): 12078 crashes
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-01-2012
Comments: Applies only to interchange influence areas. Countermeasure name changed in Jan 2014 to be more consistent with other CMFs from same study.