CMF / CRF Details

CMF ID: 322

Install a traffic signal (major road speed limit at least 40 mph)

Description: Install a traffic signal (major road speed limit at least 40 mph)

Prior Condition: No Prior Condition(s)

Category: Intersection traffic control

Study: Safety Effects of Left-Turn Phasing Schemes at High-Speed Intersections, Davis and Aul, 2007

 
Star Quality Rating: 3 Stars
Crash Modification Factor (CMF)
Value: 0.95
Adjusted Standard Error: 0.09
Unadjusted Standard Error: 0.08
Crash Reduction Factor (CRF)
Value: 5   (This value indicates a decrease in crashes)
Adjusted Standard Error: 9
Unadjusted Standard Error: 8
Applicability
Crash Type: All
Crash Severity: All
Roadway Types: Not Specified
Number of Lanes:
Road Division Type:
Speed Limit:
Area Type: Urban
Traffic Volume:
Average Traffic Volume:
Time of Day:
If countermeasure is intersection-based
Intersection Type: Roadway/roadway (not interchange related)
Intersection Geometry: 4-leg
Traffic Control: Stop-controlled
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:
Country:
Type of Methodology Used: Before/after using empirical Bayes or full Bayes
Other Details
Included in Highway Safety Manual? Yes. HSM lists this CMF in bold font to indicate that it has the highest reliability since it has an adjusted standard error of 0.1 or less. However, it also includes an asterisk (*) to indicate that the CMF value itself is within the range 0.90 to 1.10, but that the confidence interval defined by the CMF ± two times the standard error may contain the value 1.0. This is important to note since a treatment with such an CMF could potentially result in (a) a reduction in crashes (safety benefit), (b) no change, or (c) an increase in crashes (safety disbenefit). HSM recommends that this CMF should be used with caution.
Date Added to Clearinghouse: Dec-01-2009
Comments: Countermeasure name changed to match HSM