CMF / CRF Details
CMF ID: 4014
Convert frontage road from two-way operation to one-way operation
Description:
Convert frontage road from two-way operation to one-way operation
Prior Condition: frontage road with two-way operation
Category: Access management
| Crash Modification Factor (CMF) |
|---|
| Value: | 0.27 |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | |
| Crash Reduction Factor (CRF) |
|---|
| Value: | 73 (This value indicates a decrease in crashes) |
| Adjusted Standard Error: | |
| Unadjusted Standard Error: | |
| Applicability |
|---|
| Crash Type: | Rear end |
| Crash Severity: | K (fatal),A (serious injury),B (minor injury),C (possible injury) |
| Roadway Types: | Not Specified |
| 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: | |
| Minimum Speed Limit: | |
| Maximum Speed Limit: | |
| Speed Unit: | |
| Speed Limit Comment: | |
| Area Type: | Not specified |
| Traffic Volume: | |
| Average Traffic Volume: | 2996 Average Daily Traffic (ADT) |
| 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: | 1998 to 2007 |
| Municipality: | |
| State: | TX |
| Country: | U.S.A. |
| Type of Methodology Used: | Simple before/after |
| Sample Size (crashes): | 55 crashes before, 20 crashes after |
| Other Details |
|---|
| Included in Highway Safety Manual? | No |
| Date Added to Clearinghouse: | Jun 04, 2012 |
| Comments: | This CMF is for non-PDO rear-end crashes from Table 4.9 (p. 53). The CMF standard error was computed using the confidence interval given in Table 4.9 (p. 53): (CMF upper limit-CMF lower limit)/(2*1.96). The crash data consisted of records from 1998 to 2007 but excluded records from 2002 (p. 24). The study method was before-after with comparison group. Since this is not available on the list for study methodology, simple before-after was selected. The before and after sample sizes were computed using Table 4-3 (p. 46) which lists the annual crash frequency in the before and after periods and Table 3-4 (p. 36) which lists the duration of the before and after periods. The average ADT for the before and after period for each treatment site is given in Table 4-7 (p. 49); however, the overall average ADT for the treatment group is not provided. To compute the overall average ADT for the treatment group, a weighted average was taken using the treatment site average ADTs and the treatment site before and after period lengths listed in Table 3-4 (p. 36): 44*2200+60*1800+43*1800+60*2200+36*4600+60*5500+36*2600+60*3200/(44+60+43+60+36+60+36+60)=2996 |
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