CMF / CRF Details

CMF ID: 5404

Upgrade narrow unpaved shoulder (< 5 ft) to wide unpaved shoulder (> 5 ft)

Description: Upgrade narrow unpaved shoulder ( < 5 ft) to wide unpaved shoulder ( > 5 ft)

Prior Condition: Narrow unpaved shoulder ( < 5 ft)

Category: Shoulder treatments

Study: Evaluation of Safety Effectiveness of Composite Shoulders, Wide Unpaved Shoulders, and Wide Paved Shoulders in Kansas, Zeng et al., 2013

Star Quality Rating: 3 Stars   [View score details]
Rating Points Total: 90
Crash Modification Factor (CMF)
Value: 0.21
Adjusted Standard Error:
Unadjusted Standard Error: 0.038
Crash Reduction Factor (CRF)
Value: 79   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 3.8
Crash Type: Head on,Run off road,Sideswipe
Crash Severity: All
Roadway Types: Major Collector
Street Type:
Minimum Number of Lanes: 2
Maximum Number of Lanes: 2
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather: Not specified
Road Division Type: Undivided
Minimum Speed Limit:
Maximum Speed Limit:
Speed Unit:
Speed Limit Comment:
Area Type: Rural
Traffic Volume: Minimum of 65 to Maximum of 4950 Annual Average Daily Traffic (AADT)
Average Traffic Volume:
Time of Day: All
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: 2000 to 2009
State: KS
Country: USA
Type of Methodology Used: Regression cross-section
Sample Size (crashes): 430 crashes
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Jan-09-2014
Comments: The cross sectional model compares narrow unpaved shoulders to wide unpaved shoulders. There are more crashes included in the sample, specifically associated with the category "wide paved shoulders," that wasn't included in the summary statistics.