CMF / CRF Details

CMF ID: 7972

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: 0.505
Adjusted Standard Error:
Unadjusted Standard Error: 0.062
Crash Reduction Factor (CRF)
Value: 49.5   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 6.2
Applicability
Crash Type: Rear end
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
Traffic Control: Stop-controlled
Major Road Traffic Volume: Minimum of 2981 to Maximum of 18248 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume: Minimum of 1852 to Maximum of 13880 Annual Average Daily Traffic (AADT)
Average Major Road Volume : 10169 Annual Average Daily Traffic (AADT)
Average Minor Road Volume : 5970 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): 153 crashes before, 105 crashes after
Sample Size (sites): 19 sites before, 19 sites after
Sample Size (site-years): 95 site-years before, 91 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.