CMF / CRF Details

CMF ID: 4012

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

Study: Safety and Economic Impacts of Converting Two-way Frontage Roads to One-way: Methodology and Findings, Eisele et al., 2011

Star Quality Rating:2 Stars  [View score details]
Rating Points Total:35
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value:94  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type:Angle,Head on,Left turn
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
Type of Methodology Used:Simple before/after
Sample Size (crashes):40 crashes before, 2 crashes after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jun 04, 2012
Comments:This CMF is for non-PDO angle and opposite-direction crashes involving a left-turning vehicle 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