CMF / CRF Details

CMF ID: 10755

Install TWLTL (two-way left turn lane) on four lane road

Description: Converting 4-lane road to 4-lane plus one two-way turning lane.

Prior Condition: Undivided roadway

Category: Roadway

Study: Context-based Crash Modification Factors for Medians on Rural Four-Lane Roadways: A Bayesian Approach, Li et al., 2021

Star Quality Rating: 2 Stars   [View score details]
Rating Points Total: 50
Crash Modification Factor (CMF)
Value: Equation
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Reduction Factor (CRF)
Value: Equation
Adjusted Standard Error:
Unadjusted Standard Error:
Crash Type: All
Crash Severity: All
Roadway Types: Principal Arterial Other
Street Type:
Minimum Number of Lanes: 4
Maximum Number of Lanes: 4
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather: Not specified
Road Division Type: Undivided
Minimum Speed Limit: 55
Maximum Speed Limit: 65
Speed Unit: mph
Speed Limit Comment:
Area Type: Rural
Traffic Volume: Minimum of 3000 to Maximum of 24000 Annual Average Daily Traffic (AADT)
Average Traffic Volume: 8457 Annual Average Daily Traffic (AADT)
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: 2013 to 2018
State: GA
Type of Methodology Used:
Other Details
Included in Highway Safety Manual? No
Date Added to Clearinghouse: Jul-01-2021
Comments: Applies to the addition of a two-way left-turn lane (TWLTL) to a four-lane undivided highway.