CMF / CRF Details

CMF ID: 3140

Convert a Type I exit ramp to a Type III 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 III includes two exit lanes while a large percentage of traffic volume on the freeway beyond the painted nose would leave at this particular exit. An auxiliary lane to develop the full capacity of two lane exit was developed for 1500 feet. The entire operations in this type of exit ramps took place over a significant length of the freeway in most cases.

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:0.79
Adjusted Standard Error:
Unadjusted Standard Error:0.07
Crash Reduction Factor (CRF)
Value:21  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:7
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: