CMF / CRF Details
CMF ID: 5554
Converting four-lane roadways to three-lane roadways with center turn lane (road diet)
Description: Conversion of road segments from a four-lane to a three-lane cross-section with two-way left-turn lanes (also known as road diets).
Prior Condition: 4 lane roadway
Category: Roadway
Study: Iowa's Experience with Road Diet Measures - Use of Bayesian Approach to Assess Impacts on Crash Frequencies and Crash Rates, Pawlovich et al., 2006
Star Quality Rating: | [View score details] |
Rating Points Total: | 120 |
Crash Modification Factor (CMF) | |
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Value: | 0.812 |
Adjusted Standard Error: | |
Unadjusted Standard Error: | 0.005 |
Crash Reduction Factor (CRF) | |
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Value: | 18.8 (This value indicates a decrease in crashes) |
Adjusted Standard Error: | |
Unadjusted Standard Error: | 0.54 |
Applicability | |
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Crash Type: | All |
Crash Severity: | All |
Roadway Types: | Not specified |
Street Type: | |
Minimum Number of Lanes: | 4 |
Maximum Number of Lanes: | 4 |
Number of Lanes Direction: | |
Number of Lanes Comment: | |
Crash Weather: | Not specified |
Road Division Type: | Undivided |
Minimum Speed Limit: | |
Maximum Speed Limit: | |
Speed Unit: | |
Speed Limit Comment: | |
Area Type: | Urban |
Traffic Volume: | Minimum of 2030 to Maximum of 15350 Annual Average Daily Traffic (AADT) |
Average Traffic Volume: | |
Time of Day: | All |
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 | |
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Date Range of Data Used: | 1982 to 2004 |
Municipality: | |
State: | IA |
Country: | USA |
Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |