CMF / CRF Details

CMF ID: 8319

Convert diamond interchange to Diverging Diamond Interchange (DDI) or Double Crossover Diamond (DCD)

Description: Convert a diamond interchange to a Diverging Diamond Interchange (DDI) or a Double Crossover Diamond (DCD)

Prior Condition:  Diamond interchange

Category: Interchange design

Study: Safety Evaluation of Seven of the Earliest Diverging Diamond Interchanges Installed in the US, Hummer et al., 2016

 
Star Quality Rating:2 Stars  [View score details]
Rating Points Total:45
Crash Modification Factor (CMF)
Value:0.76
Adjusted Standard Error:
Unadjusted Standard Error:0.08
Crash Reduction Factor (CRF)
Value:24  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:8
Applicability
Crash Type:Single vehicle
Crash Severity:All
Roadway Types:Principal Arterial Other Freeways and Expressways
Street Type:
Minimum Number of Lanes:3
Maximum Number of Lanes:6
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:Divided by Median
Minimum Speed Limit:35
Maximum Speed Limit:45
Speed Unit:mph
Speed Limit Comment:
Area Type:Suburban
Traffic Volume:
Average Traffic Volume:30664 Annual Average Daily Traffic (AADT)
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:
Municipality:
State:KY,MO,NY,TN
Country:USA
Type of Methodology Used:Simple before/after
Sample Size (crashes):242 crashes before, 122 crashes after
Sample Size (sites):7 sites before, 7 sites after
Sample Size (site-years):28.85 site-years before, 19.03 site-years after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jan 17, 2017
Comments:The volume here is the crossover volume.