CMF / CRF Details

CMF ID: 7973

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: 0.892
Adjusted Standard Error:
Unadjusted Standard Error: 0.08
Crash Reduction Factor (CRF)
Value: 10.8   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 8
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: 4-leg
Traffic Control: Stop-controlled
Major Road Traffic Volume: Minimum of 1360 to Maximum of 15500 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume: Minimum of 1036 to Maximum of 8884 Annual Average Daily Traffic (AADT)
Average Major Road Volume : 8555 Annual Average Daily Traffic (AADT)
Average Minor Road Volume : 3997 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): 226 crashes before, 208 crashes after
Sample Size (sites): 48 sites before, 48 sites after
Sample Size (site-years): 238 site-years before, 228 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.