The main objective of this 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. Several median and roadway design features were evaluated. Of the four types of median openings, uni-directional median opening on a four-lane facility was the safest and full median opening with left-turn bays on both directions on a six-lane facility was the least safe. Further, compared to four-lane facilities, crash rates at median openings on six-lane facilities were consistently higher. Median conversion was found to result in a greater overall safety benefit for six-lane facilities compared to four-lane facilities. Specific safety issues of raised medians examined in this study included vehicles directly hitting the median curb, median crossover crashes, and pedestrian crashes. Of the 2,436 crashes that occurred at the 18 locations after median conversion, 48 (2.0 percent) involved vehicles directly hitting the median curb, and 38 (1.6 percent) involved vehicles crossing over the median. Of the 46 pedestrian crashes that occurred after median conversion, none were hit while standing on the raised median. Another main objective of this study was to document the experience of businesses on corridors that were recently converted from TWLTLs to raised medians and their involvement in the public information process. On-site interviews of businesses at ten roadway segments were conducted and responses from 151 businesses were included in the analysis. A majority of the responding businesses preferred TWLTLs to raised medians for better access and ease of truck deliveries. Two-thirds of the responding businesses thought that raised medians were safer than TWLTLs. Of the 151 businesses, 40 indicated that they were informed of public hearings on the raised median construction projects. Of these, only 13 indicated that they attended at least one public hearing (Author/publisher)
Abstract