CMF / CRF Details
CMF ID: 5553
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) | |
|---|---|
| Value: | 0.748 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.012 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 25.2 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 1.17 |
| Applicability | |
|---|---|
| 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 | |
|---|---|
| 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 |
