CMF / CRF Details
Convert diamond interchange to Diverging Diamond Interchange (DDI) or Double Crossover Diamond (DCD)
Countermeasure ID: 6890
Description: Convert a diamond interchange to a Diverging Diamond Interchange (DDI) or a Double Crossover Diamond (DCD)
Prior Condition: Conventional diamond interchange
Category: Interchange design
Study: Safety Evaluation of Diverging Diamond Interchanges in Missouri, Edara et al., 2015
Study Type: Project Report
| Star Quality Rating: |  [View score details] |
| Rating Points Total: | |
| Crash Modification Factor (CMF) | |
|---|---|
| Value: | 0.649 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.037 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 35.1 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 3.7 |
| Applicability | |
|---|---|
| Crash Type: | All |
| Crash Severity: | O (property damage only) |
| Roadway Types: | All |
| Street Type: | |
| Minimum Number of Lanes: | 3 |
| Maximum Number of Lanes: | |
| Number of Lanes Direction: | Both Directions |
| Number of Lanes Comment: | Multi Lane |
| Crash Weather: | Not specified |
| Road Division Type: | |
| Minimum Speed Limit: | 60 |
| Maximum Speed Limit: | 65 |
| Speed Unit: | mph |
| Speed Limit Comment: | 60 - 65 mph on Freeway / 35 - 40 mph on Crossroad |
| Area Type: | Not specified |
| Traffic Volume: | |
| Average Traffic Volume: | |
| Time of Day: | All |
| If countermeasure is intersection-based | |
| Intersection Type: | Other |
| Intersection Geometry: | No values chosen. |
| Traffic Control: | Other |
| Major Road Traffic Volume: | Minimum of 32604 to Maximum of 151923 Annual Average Daily Traffic (AADT) |
| Minor Road Traffic Volume: | Minimum of 16087 to Maximum of 29275 Annual Average Daily Traffic (AADT) |
| Average Major Road Volume : | 72987 Annual Average Daily Traffic (AADT) |
| Average Minor Road Volume : | 23948 Annual Average Daily Traffic (AADT) |
| Development Details | |
|---|---|
| Date Range of Data Used: | 2005 to 2013 |
| Municipality: | |
| State: | MO |
| Country: | USA |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Sample Size (crashes): | 1079 crashes before, 506 crashes after |
| Sample Size (sites): | 6 sites before, 6 sites after |
| Sample Size (site-years): | 21 site-years before, 14.83 site-years after |
