CMF / CRF Details

CMF ID: 2797

Install positive offset left turn lanes

Description: Install offset left turn lanes to improve sight distance

Prior Condition:  No Prior Condition(s)

Category: Intersection geometry

Study: NCHRP Report 650 - Median Intersection Design for Rural High-Speed Divided Highways, Maze et al., 2010

 
Star Quality Rating:1 Star  [View score details]
Rating Points Total:20
Crash Modification Factor (CMF)
Value:0.67
Adjusted Standard Error:
Unadjusted Standard Error:0.2
Crash Reduction Factor (CRF)
Value:33  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:20.1
Applicability
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:55
Maximum Speed Limit:55
Speed Unit:mph
Speed Limit Comment:
Area Type:Rural
Traffic Volume:
Average Traffic Volume:
Time of Day:All
If countermeasure is intersection-based
Intersection Type:Roadway/roadway (not interchange related)
Intersection Geometry:4-leg
Traffic Control:Stop-controlled
Major Road Traffic Volume:Minimum of 27400 to Maximum of 33100 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume:
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used:1999 to 2006
Municipality:New Hanover County
State:NC
Country:USA
Type of Methodology Used:Simple before/after
Sample Size (crashes):26 crashes before, 20 crashes after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Mar 21, 2011
Comments:For 1 site. The intersection just south of the site was signalized during the before period. That signal opens gaps in traffic and may have contributed to a drop in some crash types.