CMF / CRF Details
CMF ID: 2928
Decreasing posted speed limit on expressways
Description: Decreasing posted speed limit (from 100 km/h (62 mph) to 80 km/h (50 mph)) on expressways
Prior Condition: Expressway with posted speed limit of 100 km/h (with one exception posted at 80 km/h)
Category: Speed management
Study: A fully Bayesian multivariate approach to before-after safety evaluation, Park et al. (2010), 2010
| Star Quality Rating: |  [View score details] |
| Rating Points Total: | 110 |
| Crash Modification Factor (CMF) | |
|---|---|
| Value: | 0.8553 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 0.0792 |
| Crash Reduction Factor (CRF) | |
|---|---|
| Value: | 14.4 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | 7.92 |
| Applicability | |
|---|---|
| Crash Type: | All |
| Crash Severity: | All |
| Roadway Types: | Principal Arterial Other Freeways and Expressways |
| Street Type: | |
| Minimum Number of Lanes: | |
| Maximum Number of Lanes: | |
| Number of Lanes Direction: | |
| Number of Lanes Comment: | |
| Crash Weather: | Not specified |
| Road Division Type: | Divided by Median |
| Minimum Speed Limit: | 100 |
| Maximum Speed Limit: | 100 |
| Speed Unit: | km/h |
| Speed Limit Comment: | 100 km/h reduced to 80 km/h |
| Area Type: | Not specified |
| Traffic Volume: | Minimum of 3100 to Maximum of 50300 |
| 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: | 1994 to 2006 |
| Municipality: | |
| State: | notusa |
| Country: | Korea |
| Type of Methodology Used: | Before/after using empirical Bayes or full Bayes |
| Sample Size (site-years): | 150 site-years before, 246 site-years after |
| Other Details | |
|---|---|
| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Mar 21, 2011 |
| Comments: | |
