CMF / CRF Details

CMF ID: 7968

Install a traffic signal and left turn lanes

Description: Install a traffic signal and left turn lanes

Prior Condition: Intersections with a stop sign on minor roads

Category: Intersection traffic control

Study: Safety Evaluation of Signal Installation With and Without Left Turn Lanes on Two Lane Roads in Rural and Suburban Areas, Srinivasan et al., 2014

 
Star Quality Rating: 4 Stars   [View score details]
Crash Modification Factor (CMF)
Value: 0.561
Adjusted Standard Error:
Unadjusted Standard Error: 0.024
Crash Reduction Factor (CRF)
Value: 43.9   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 2.4
Applicability
Crash Type: All
Crash Severity: All
Roadway Types: Not specified
Number of Lanes: 2
Road Division Type:
Speed Limit:
Area Type: All
Traffic Volume:
Average Traffic Volume:
Time of Day: All
If countermeasure is intersection-based
Intersection Type: Not specified
Intersection Geometry: 3-leg,4-leg
Traffic Control: Stop-controlled
Major Road Traffic Volume: Minimum of 1360 to Maximum of 18248 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume: Minimum of 1036 to Maximum of 13880 Annual Average Daily Traffic (AADT)
Average Major Road Volume : 11896 Annual Average Daily Traffic (AADT)
Average Minor Road Volume : 6249 Annual Average Daily Traffic (AADT)
Development Details
Date Range of Data Used: 1992 to 2012
Municipality:
State: NC
Country:
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Sample Size (crashes): 1469 crashes before, 840 crashes after
Sample Size (sites): 67 sites before, 67 sites after
Sample Size (site-years): 333 site-years before, 319 site-years after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-10-2016
Comments: The CMF was developed for both rural and suburban areas.