CMF / CRF Details

CMF ID: 8982

Install oversized chevron signs

Description: Curve warning treatment with oversized chevron signs

Prior Condition: smaller 12x18in or 24x30in signs

Category: Signs

Study: Safety Evaluation of Two Curve Warning Treatments: In-Lane Curve Warning Pavement Markings and Oversized Chevron Signs, Lyon et al., 2017

 
Star Quality Rating: 4 Stars   [View score details]
Rating Points Total: 130
Crash Modification Factor (CMF)
Value: 0.56
Adjusted Standard Error:
Unadjusted Standard Error: 0.184
Crash Reduction Factor (CRF)
Value: 44   (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error: 18.4
Applicability
Crash Type: Nighttime
Crash Severity: All
Roadway Types: Not specified
Number of Lanes:
Road Division Type:
Speed Limit:
Area Type: Not specified
Traffic Volume: Minimum of 173 to Maximum of 27235 Annual Average Daily Traffic (AADT)
Average Traffic Volume:
Time of Day: Night
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: IA, KS, MO
Country: USA
Type of Methodology Used: 2
Sample Size (sites): 45 sites before, 45 sites after
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Nov-17-2017
Comments: Presence of advisory speed signs The number of crashes in the after period were not reported in this study, however, they have been recorded as 300 to give 10 points as a beneift of doubt for one or more of the following: (1) number of miles/sites in the reference/treatment group, (2) number of crashes in the references/treatment group, (3) reporting AADTs for the aggregate dataset but not for the disaggragate dataset used for CMF development.