Study Details

Study Title: Before-and-after safety study of roadways Where new medians have been added

Authors: Alluri et al.

Publication Date:DEC, 2012

Abstract: The main objective of the study was to evaluate the safety impact of median conversion from two-way left-turn lanes (TWLTLs) to raised medians in Florida. Based on segment length and data availability, 18 locations totaling 17.51 miles were selected for before-and-after analysis. Police reports of all the crashes before and after median conversion were reviewed to correct miscoded crash types and obtain additional detailed crash information. The safety performance of individual locations varied in terms of crash type and crash severity. Overall, the results showed a 30.3 percent reduction in the total crash rate after median conversion. Median conversion was particularly effective in reducing rear-end, angle, left-turn, and right-turn crash rates. Further review of three locations that performed particularly poorly revealed that the majority of crashes that occurred after conversion could not be attributed directly to raised medians.

Study Citation: Alluri, P., Gan, A., Haleem, K., Miranda, S., Echezabal, E., Diaz, A., Ding, S. "Before-and-after safety study of roadways Where new medians have been added." Florida Department of Transportation, (2012).

Related Citations: Allrui, P., A. Gan, and K. Haleem. Safety Impacts of Converting Two-Way Left-Turn Lanes to Raised Medians and Associated Design Concerns. Presented at the 93rd Annual Meeting of the Transportation Research Board, Washington, D.C., (2014).

Study Report: Download the Study Report Document


CMFs Associated With This Study

Category: Access management

Countermeasure: Provide a raised median

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.9782.21 StarVehicle/bicycleAllPrincipal Arterial OtherUrban and suburban
0.9633.71 StarOtherAllPrincipal Arterial OtherUrban and suburban
0.73526.52 StarsAllAllPrincipal Arterial OtherUrban and suburban
0.78321.72 StarsAllOPrincipal Arterial OtherUrban and suburban
0.69530.52 StarsAllA,B,CPrincipal Arterial OtherUrban and suburban
0.71628.41 StarAllKPrincipal Arterial OtherUrban and suburban
0.69530.52 StarsAllK,A,B,CPrincipal Arterial OtherUrban and suburban
0.68431.62 StarsDay timeAllPrincipal Arterial OtherUrban and suburban
0.62537.52 StarsNighttimeAllPrincipal Arterial OtherUrban and suburban
0.44455.62 StarsNighttimeAllPrincipal Arterial OtherUrban and suburban
0.9287.21 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
1.181-18.11 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.41858.22 StarsOtherAllPrincipal Arterial OtherUrban and suburban
0.52847.21 StarAllKPrincipal Arterial OtherUrban and suburban
0.9653.51 StarAllK,A,B,CPrincipal Arterial OtherUrban and suburban
0.9732.71 StarDay timeAllPrincipal Arterial OtherUrban and suburban
0.9980.21 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.50349.71 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.9821 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.44561 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.37762.32 StarsOtherAllPrincipal Arterial OtherUrban and suburban
0.47752.32 StarsHead onAllPrincipal Arterial OtherUrban and suburban
0.74225.82 StarsRear endAllPrincipal Arterial OtherUrban and suburban
0.55844.22 StarsAngleAllPrincipal Arterial OtherUrban and suburban
0.26273.82 StarsLeft turnAllPrincipal Arterial OtherUrban and suburban
0.52947.12 StarsRight turnAllPrincipal Arterial OtherUrban and suburban
0.9049.61 StarSideswipeAllPrincipal Arterial OtherUrban and suburban
0.59640.42 StarsVehicle/pedestrianAllPrincipal Arterial OtherUrban and suburban
1.006-0.61 StarVehicle/bicycleAllPrincipal Arterial OtherUrban and suburban
0.82717.32 StarsOtherAllPrincipal Arterial OtherUrban and suburban
0.62837.22 StarsAllAllPrincipal Arterial OtherUrban and suburban
0.68431.62 StarsAllOPrincipal Arterial OtherUrban and suburban
0.58422 StarsAllA,B,CPrincipal Arterial OtherUrban and suburban
0.79120.91 StarAllKPrincipal Arterial OtherUrban and suburban
0.58241.82 StarsAllK,A,B,CPrincipal Arterial OtherUrban and suburban
0.56443.62 StarsDay timeAllPrincipal Arterial OtherUrban and suburban
0.51248.82 StarsNighttimeAllPrincipal Arterial OtherUrban and suburban
0.41658.42 StarsNighttimeAllPrincipal Arterial OtherUrban and suburban
0.85914.12 StarsNighttimeAllPrincipal Arterial OtherUrban and suburban
0.9316.91 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.46553.52 StarsOtherAllPrincipal Arterial OtherUrban and suburban
0.27572.52 StarsHead onAllPrincipal Arterial OtherUrban and suburban
0.75624.42 StarsRear endAllPrincipal Arterial OtherUrban and suburban
0.46253.82 StarsAngleAllPrincipal Arterial OtherUrban and suburban
0.32667.42 StarsLeft turnAllPrincipal Arterial OtherUrban and suburban
0.9435.71 StarRight turnAllPrincipal Arterial OtherUrban and suburban
1.186-18.61 StarSideswipeAllPrincipal Arterial OtherUrban and suburban
1.237-23.71 StarVehicle/pedestrianAllPrincipal Arterial OtherUrban and suburban
1.031-3.11 StarVehicle/bicycleAllPrincipal Arterial OtherUrban and suburban
0.82517.51 StarOtherAllPrincipal Arterial OtherUrban and suburban
0.68231.82 StarsAllAllPrincipal Arterial OtherUrban and suburban
0.71228.82 StarsAllOPrincipal Arterial OtherUrban and suburban
0.64335.72 StarsAllA,B,CPrincipal Arterial OtherUrban and suburban
0.65434.62 StarsAllK,A,B,CPrincipal Arterial OtherUrban and suburban
0.63936.12 StarsDay timeAllPrincipal Arterial OtherUrban and suburban
1.65-651 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.55451 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.86713.31 StarNighttimeAllPrincipal Arterial OtherUrban and suburban
0.41258.82 StarsNighttimeAllPrincipal Arterial OtherUrban and suburban
0.58841.21 StarHead onAllPrincipal Arterial OtherUrban and suburban
0.88111.92 StarsRear endAllPrincipal Arterial OtherUrban and suburban
0.64735.32 StarsAngleAllPrincipal Arterial OtherUrban and suburban
0.34865.22 StarsLeft turnAllPrincipal Arterial OtherUrban and suburban
0.66333.72 StarsRight turnAllPrincipal Arterial OtherUrban and suburban
0.81818.22 StarsSideswipeAllPrincipal Arterial OtherUrban and suburban
0.70929.12 StarsVehicle/pedestrianAllPrincipal Arterial OtherUrban and suburban
0.74225.82 StarsAllOPrincipal Arterial OtherUrban and suburban
0.65934.12 StarsAllA,B,CPrincipal Arterial OtherUrban and suburban
0.77822.21 StarAllKPrincipal Arterial OtherUrban and suburban
0.66342 StarsAllK,A,B,CPrincipal Arterial OtherUrban and suburban
0.69730.32 StarsAllAllPrincipal Arterial OtherUrban and suburban
0.85214.81 StarHead onOPrincipal Arterial OtherUrban and suburban
0.29270.82 StarsHead onA,B,CPrincipal Arterial OtherUrban and suburban
01002 StarsHead onKPrincipal Arterial OtherUrban and suburban
0.26573.52 StarsHead onK,A,B,CPrincipal Arterial OtherUrban and suburban
0.51248.82 StarsHead onAllPrincipal Arterial OtherUrban and suburban
0.89610.42 StarsRear endOPrincipal Arterial OtherUrban and suburban
0.77722.32 StarsRear endA,B,CPrincipal Arterial OtherUrban and suburban
0.77622.42 StarsRear endK,A,B,CPrincipal Arterial OtherUrban and suburban
0.83172 StarsRear endAllPrincipal Arterial OtherUrban and suburban
0.54445.62 StarsAngleOPrincipal Arterial OtherUrban and suburban
0.64362 StarsAngleA,B,CPrincipal Arterial OtherUrban and suburban
0.9732.71 StarAngleKPrincipal Arterial OtherUrban and suburban
0.64135.92 StarsAngleK,A,B,CPrincipal Arterial OtherUrban and suburban
0.59540.52 StarsAngleAllPrincipal Arterial OtherUrban and suburban
0.39760.32 StarsLeft turnOPrincipal Arterial OtherUrban and suburban
0.29570.52 StarsLeft turnA,B,CPrincipal Arterial OtherUrban and suburban
0.24375.72 StarsLeft turnKPrincipal Arterial OtherUrban and suburban
0.29470.62 StarsLeft turnK,A,B,CPrincipal Arterial OtherUrban and suburban
0.32967.12 StarsLeft turnAllPrincipal Arterial OtherUrban and suburban
0.57142.92 StarsRight turnOPrincipal Arterial OtherUrban and suburban
0.9257.51 StarRight turnA,B,CPrincipal Arterial OtherUrban and suburban
0.9257.51 StarRight turnK,A,B,CPrincipal Arterial OtherUrban and suburban
0.66133.92 StarsRight turnAllPrincipal Arterial OtherUrban and suburban
0.85914.11 StarSideswipeOPrincipal Arterial OtherUrban and suburban
0.74325.71 StarSideswipeA,B,CPrincipal Arterial OtherUrban and suburban
0.74325.71 StarSideswipeK,A,B,CPrincipal Arterial OtherUrban and suburban
0.83172 StarsSideswipeAllPrincipal Arterial OtherUrban and suburban
0.48751.31 StarVehicle/pedestrianOPrincipal Arterial OtherUrban and suburban
0.66133.92 StarsVehicle/pedestrianA,B,CPrincipal Arterial OtherUrban and suburban
1.704-70.41 StarVehicle/pedestrianKPrincipal Arterial OtherUrban and suburban
0.73426.62 StarsVehicle/pedestrianK,A,B,CPrincipal Arterial OtherUrban and suburban
0.71128.92 StarsVehicle/pedestrianAllPrincipal Arterial OtherUrban and suburban
0.81118.91 StarVehicle/bicycleOPrincipal Arterial OtherUrban and suburban
1.018-1.81 StarVehicle/bicycleA,B,CPrincipal Arterial OtherUrban and suburban
0.48751.31 StarVehicle/bicycleKPrincipal Arterial OtherUrban and suburban
0.9732.71 StarVehicle/bicycleK,A,B,CPrincipal Arterial OtherUrban and suburban
0.9554.51 StarVehicle/bicycleAllPrincipal Arterial OtherUrban and suburban
1.173-17.32 StarsRear endAllPrincipal Arterial OtherUrban and suburban
0.73226.82 StarsAngleAllPrincipal Arterial OtherUrban and suburban
0.66433.62 StarsLeft turnAllPrincipal Arterial OtherUrban and suburban
0.9742.61 StarRight turnAllPrincipal Arterial OtherUrban and suburban
0.59740.32 StarsSideswipeAllPrincipal Arterial OtherUrban and suburban
1.37-371 StarVehicle/pedestrianAllPrincipal Arterial OtherUrban and suburban
0.70529.51 StarVehicle/bicycleAllPrincipal Arterial OtherUrban and suburban
1.028-2.81 StarOtherAllPrincipal Arterial OtherUrban and suburban
0.9534.71 StarAllAllPrincipal Arterial OtherUrban and suburban
0.9415.91 StarAllOPrincipal Arterial OtherUrban and suburban
0.9742.61 StarAllA,B,CPrincipal Arterial OtherUrban and suburban