CMF / CRF Details

CMF ID: 4017

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:60
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value:68  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type:All
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):56 crashes before, 22 crashes after
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Jun 04, 2012
Comments:This CMF is for non-PDO incapacitating injury, non-incapacitating injury, and fatality crashes from Table 4.9 (p. 53). Since “possible injury” is not listed under crash severity in the CMF Clearinghouse, this CMF entry will have the same severities selected as ID 4010 which is for total non-PDO crashes (i.e., fatal, serious injury, and minor injury). The absence of “possible injury” from the crash severity list, therefore, may cause some confusion among Clearinghouse users. 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 4-5 (p. 48) 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