CMF / CRF Details

CMF ID: 8335

Install an additional lane

Description: Use reducing lane and shoulder width to install additional lanes for urban freeway

Prior Condition:  Freeway with fewer lanes

Category: Roadway

Study: Operational and Safety Trade-offs: Reducing Freeway Lane and Shoulder Width to Permit an Additional Lane, Dixon et al., 2016

 
Star Quality Rating:3 Stars  [View score details]
Rating Points Total:80
Crash Modification Factor (CMF)
Value:0.75
Adjusted Standard Error:
Unadjusted Standard Error:0.095
Crash Reduction Factor (CRF)
Value:25  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:9.5
Applicability
Crash Type:All
Crash Severity:K (fatal),A (serious injury),B (minor injury),C (possible injury)
Roadway Types:Principal Arterial Other Freeways and Expressways
Street Type:
Minimum Number of Lanes:2
Maximum Number of Lanes:5
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:Divided by Median
Minimum Speed Limit:50
Maximum Speed Limit:
Speed Unit:mph
Speed Limit Comment:> = 50 mph
Area Type:Urban
Traffic Volume:Minimum of 200 to Maximum of 281450 Average Daily Traffic (ADT)
Average Traffic Volume:152163 Average Daily Traffic (ADT)
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:2010 to 2013
Municipality:Dallas, Houston, San Antonio
State:TX
Country:USA
Type of Methodology Used:Regression cross-section
Sample Size (crashes):407 crashes
Sample Size (sites):536 sites
Sample Size (site-years):2104 site-years
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jan 17, 2017
Comments:CMFs of adding one additional lane with 11.5 ft average lane width