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(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
---|
0.978 | 2.2 | | Vehicle/bicycle | All | Principal Arterial Other | Urban and suburban |
0.963 | 3.7 | | Other | All | Principal Arterial Other | Urban and suburban |
0.735 | 26.5 | | All | All | Principal Arterial Other | Urban and suburban |
0.783 | 21.7 | | All | O | Principal Arterial Other | Urban and suburban |
0.695 | 30.5 | | All | A,B,C | Principal Arterial Other | Urban and suburban |
0.716 | 28.4 | | All | K | Principal Arterial Other | Urban and suburban |
0.695 | 30.5 | | All | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.684 | 31.6 | | Day time | All | Principal Arterial Other | Urban and suburban |
0.625 | 37.5 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.444 | 55.6 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.928 | 7.2 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
1.181 | -18.1 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.418 | 58.2 | | Other | All | Principal Arterial Other | Urban and suburban |
0.528 | 47.2 | | All | K | Principal Arterial Other | Urban and suburban |
0.965 | 3.5 | | All | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.973 | 2.7 | | Day time | All | Principal Arterial Other | Urban and suburban |
0.998 | 0.2 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.503 | 49.7 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.98 | 2 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.44 | 56 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.377 | 62.3 | | Other | All | Principal Arterial Other | Urban and suburban |
0.477 | 52.3 | | Head on | All | Principal Arterial Other | Urban and suburban |
0.742 | 25.8 | | Rear end | All | Principal Arterial Other | Urban and suburban |
0.558 | 44.2 | | Angle | All | Principal Arterial Other | Urban and suburban |
0.262 | 73.8 | | Left turn | All | Principal Arterial Other | Urban and suburban |
0.529 | 47.1 | | Right turn | All | Principal Arterial Other | Urban and suburban |
0.904 | 9.6 | | Sideswipe | All | Principal Arterial Other | Urban and suburban |
0.596 | 40.4 | | Vehicle/pedestrian | All | Principal Arterial Other | Urban and suburban |
1.006 | -0.6 | | Vehicle/bicycle | All | Principal Arterial Other | Urban and suburban |
0.827 | 17.3 | | Other | All | Principal Arterial Other | Urban and suburban |
0.628 | 37.2 | | All | All | Principal Arterial Other | Urban and suburban |
0.684 | 31.6 | | All | O | Principal Arterial Other | Urban and suburban |
0.58 | 42 | | All | A,B,C | Principal Arterial Other | Urban and suburban |
0.791 | 20.9 | | All | K | Principal Arterial Other | Urban and suburban |
0.582 | 41.8 | | All | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.564 | 43.6 | | Day time | All | Principal Arterial Other | Urban and suburban |
0.512 | 48.8 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.416 | 58.4 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.859 | 14.1 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.931 | 6.9 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.465 | 53.5 | | Other | All | Principal Arterial Other | Urban and suburban |
0.275 | 72.5 | | Head on | All | Principal Arterial Other | Urban and suburban |
0.756 | 24.4 | | Rear end | All | Principal Arterial Other | Urban and suburban |
0.462 | 53.8 | | Angle | All | Principal Arterial Other | Urban and suburban |
0.326 | 67.4 | | Left turn | All | Principal Arterial Other | Urban and suburban |
0.943 | 5.7 | | Right turn | All | Principal Arterial Other | Urban and suburban |
1.186 | -18.6 | | Sideswipe | All | Principal Arterial Other | Urban and suburban |
1.237 | -23.7 | | Vehicle/pedestrian | All | Principal Arterial Other | Urban and suburban |
1.031 | -3.1 | | Vehicle/bicycle | All | Principal Arterial Other | Urban and suburban |
0.825 | 17.5 | | Other | All | Principal Arterial Other | Urban and suburban |
0.682 | 31.8 | | All | All | Principal Arterial Other | Urban and suburban |
0.712 | 28.8 | | All | O | Principal Arterial Other | Urban and suburban |
0.643 | 35.7 | | All | A,B,C | Principal Arterial Other | Urban and suburban |
0.654 | 34.6 | | All | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.639 | 36.1 | | Day time | All | Principal Arterial Other | Urban and suburban |
1.65 | -65 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.55 | 45 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.867 | 13.3 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.412 | 58.8 | | Nighttime | All | Principal Arterial Other | Urban and suburban |
0.588 | 41.2 | | Head on | All | Principal Arterial Other | Urban and suburban |
0.881 | 11.9 | | Rear end | All | Principal Arterial Other | Urban and suburban |
0.647 | 35.3 | | Angle | All | Principal Arterial Other | Urban and suburban |
0.348 | 65.2 | | Left turn | All | Principal Arterial Other | Urban and suburban |
0.663 | 33.7 | | Right turn | All | Principal Arterial Other | Urban and suburban |
0.818 | 18.2 | | Sideswipe | All | Principal Arterial Other | Urban and suburban |
0.709 | 29.1 | | Vehicle/pedestrian | All | Principal Arterial Other | Urban and suburban |
0.742 | 25.8 | | All | O | Principal Arterial Other | Urban and suburban |
0.659 | 34.1 | | All | A,B,C | Principal Arterial Other | Urban and suburban |
0.778 | 22.2 | | All | K | Principal Arterial Other | Urban and suburban |
0.66 | 34 | | All | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.697 | 30.3 | | All | All | Principal Arterial Other | Urban and suburban |
0.852 | 14.8 | | Head on | O | Principal Arterial Other | Urban and suburban |
0.292 | 70.8 | | Head on | A,B,C | Principal Arterial Other | Urban and suburban |
0 | 100 | | Head on | K | Principal Arterial Other | Urban and suburban |
0.265 | 73.5 | | Head on | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.512 | 48.8 | | Head on | All | Principal Arterial Other | Urban and suburban |
0.896 | 10.4 | | Rear end | O | Principal Arterial Other | Urban and suburban |
0.777 | 22.3 | | Rear end | A,B,C | Principal Arterial Other | Urban and suburban |
0.776 | 22.4 | | Rear end | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.83 | 17 | | Rear end | All | Principal Arterial Other | Urban and suburban |
0.544 | 45.6 | | Angle | O | Principal Arterial Other | Urban and suburban |
0.64 | 36 | | Angle | A,B,C | Principal Arterial Other | Urban and suburban |
0.973 | 2.7 | | Angle | K | Principal Arterial Other | Urban and suburban |
0.641 | 35.9 | | Angle | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.595 | 40.5 | | Angle | All | Principal Arterial Other | Urban and suburban |
0.397 | 60.3 | | Left turn | O | Principal Arterial Other | Urban and suburban |
0.295 | 70.5 | | Left turn | A,B,C | Principal Arterial Other | Urban and suburban |
0.243 | 75.7 | | Left turn | K | Principal Arterial Other | Urban and suburban |
0.294 | 70.6 | | Left turn | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.329 | 67.1 | | Left turn | All | Principal Arterial Other | Urban and suburban |
0.571 | 42.9 | | Right turn | O | Principal Arterial Other | Urban and suburban |
0.925 | 7.5 | | Right turn | A,B,C | Principal Arterial Other | Urban and suburban |
0.925 | 7.5 | | Right turn | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.661 | 33.9 | | Right turn | All | Principal Arterial Other | Urban and suburban |
0.859 | 14.1 | | Sideswipe | O | Principal Arterial Other | Urban and suburban |
0.743 | 25.7 | | Sideswipe | A,B,C | Principal Arterial Other | Urban and suburban |
0.743 | 25.7 | | Sideswipe | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.83 | 17 | | Sideswipe | All | Principal Arterial Other | Urban and suburban |
0.487 | 51.3 | | Vehicle/pedestrian | O | Principal Arterial Other | Urban and suburban |
0.661 | 33.9 | | Vehicle/pedestrian | A,B,C | Principal Arterial Other | Urban and suburban |
1.704 | -70.4 | | Vehicle/pedestrian | K | Principal Arterial Other | Urban and suburban |
0.734 | 26.6 | | Vehicle/pedestrian | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.711 | 28.9 | | Vehicle/pedestrian | All | Principal Arterial Other | Urban and suburban |
0.811 | 18.9 | | Vehicle/bicycle | O | Principal Arterial Other | Urban and suburban |
1.018 | -1.8 | | Vehicle/bicycle | A,B,C | Principal Arterial Other | Urban and suburban |
0.487 | 51.3 | | Vehicle/bicycle | K | Principal Arterial Other | Urban and suburban |
0.973 | 2.7 | | Vehicle/bicycle | K,A,B,C | Principal Arterial Other | Urban and suburban |
0.955 | 4.5 | | Vehicle/bicycle | All | Principal Arterial Other | Urban and suburban |
1.173 | -17.3 | | Rear end | All | Principal Arterial Other | Urban and suburban |
0.732 | 26.8 | | Angle | All | Principal Arterial Other | Urban and suburban |
0.664 | 33.6 | | Left turn | All | Principal Arterial Other | Urban and suburban |
0.974 | 2.6 | | Right turn | All | Principal Arterial Other | Urban and suburban |
0.597 | 40.3 | | Sideswipe | All | Principal Arterial Other | Urban and suburban |
1.37 | -37 | | Vehicle/pedestrian | All | Principal Arterial Other | Urban and suburban |
0.705 | 29.5 | | Vehicle/bicycle | All | Principal Arterial Other | Urban and suburban |
1.028 | -2.8 | | Other | All | Principal Arterial Other | Urban and suburban |
0.953 | 4.7 | | All | All | Principal Arterial Other | Urban and suburban |
0.941 | 5.9 | | All | O | Principal Arterial Other | Urban and suburban |
0.974 | 2.6 | | All | A,B,C | Principal Arterial Other | Urban and suburban |