CMF / CRF Details

CMF ID: 3139

Convert a Type I exit ramp to a Type II exit ramp

Description: Type I is a full width parallel from tangent that leads to either a tangent or flat exiting curve which includes a decelerating taper. The horizontal and vertical alignment of type I exit ramps were based on the selected design speed equal or less than the intersecting roadways. Type II is when the outer lane becomes a drop lane at the exit gore forming a lane reduction. A paved and striped area beyond the theoretical gore were present at this type of exit ramps to provide a maneuver and recovery area.

Prior Condition:  No Prior Condition(s)

Category: Interchange design

Study: Safety Evaluation of Truck-Related Crashes at Freeway Diverge Areas, Zhenyu Wang, Bin Cao, Weiping Deng, Jian John Lu, and Zhao Zhang, 2011

 
Star Quality Rating:4 Stars  [View score details]
Rating Points Total:115
Crash Modification Factor (CMF)
Value:1.21
Adjusted Standard Error:
Unadjusted Standard Error:0.1
Crash Reduction Factor (CRF)
Value:-21  (This value indicates an increase in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:10
Applicability
Crash Type:Truck related
Crash Severity:All
Roadway Types:Principal Arterial Other Freeways and Expressways
Street Type:
Minimum Number of Lanes:
Maximum Number of Lanes:
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:Not specified
Traffic Volume:
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:2005 to 2008
Municipality:
State:FL
Country:usa
Type of Methodology Used:Regression cross-section
Sample Size (crashes):4630 crashes
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jul 15, 2011
Comments: