CMF / CRF Details

CMF ID: 11067

Install left-in left-out (LILO) treatment

Description: Left-in left-out (LILO) treatments are typically applied on arterial roadways with medians and consist of a channelizing island in the median which helps direct vehicles turning left both on to and out of minor streets or driveways. Additionally, the treatment contains an exclusive left turn lane for vehicles turning left on to minor streets/driveways and left turn refuge with varying acceleration lane lengths for vehicles turning left out of minor streets/driveways (these left-turning vehicles then merge with major street traffic).

Prior Condition:  No Prior Condition(s)

Category: Access management

Study: Analysis of the Safety Impacts of the Left-In Left-Out Median Opening Treatment at Intersections/Driveways, Russo et al., 2021

Star Quality Rating:3 Stars  [View score details]
Rating Points Total:85
Crash Modification Factor (CMF)
Adjusted Standard Error:
Unadjusted Standard Error:0.216
Crash Reduction Factor (CRF)
Value:15.4  (This value indicates a decrease in crashes)
Adjusted Standard Error:
Unadjusted Standard Error:21.6
Crash Type:All
Crash Severity:K (fatal),A (serious injury),B (minor injury)
Roadway Types:Not specified
Street Type:
Minimum Number of Lanes:4
Maximum Number of Lanes:8
Number of Lanes Direction:
Number of Lanes Comment:
Crash Weather:Not specified
Road Division Type:Divided by Median
Minimum Speed Limit:30
Maximum Speed Limit:50
Speed Unit:mph
Speed Limit Comment:
Area Type:Urban and suburban
Traffic Volume:
Average Traffic Volume:
Time of Day:Not specified
If countermeasure is intersection-based
Intersection Type:Roadway/roadway (not interchange related)
Intersection Geometry:3-leg,4-leg
Traffic Control:Stop-controlled
Major Road Traffic Volume:Minimum of 7722 to Maximum of 46584 Annual Average Daily Traffic (AADT)
Minor Road Traffic Volume:Minimum of 64 to Maximum of 2509 Annual Average Daily Traffic (AADT)
Average Major Road Volume :
Average Minor Road Volume :
Development Details
Date Range of Data Used:2014 to 2019
Type of Methodology Used:
Other Details
Included in Highway Safety Manual?No
Date Added to Clearinghouse:Mar 16, 2022