Abstract

Safety improvements are often controversial subjects, especially when the subject is highways. Judgments must be made weighing lives and injuries against the hard realities of financing the construction and maintenance of highway systems. Median crossovers on rural and urban freeways and expressways are controversial design features. State police and maintenance forces claim that median crossovers are necessary and essential for their work and that more frequent location of crossovers is desirable. Engineers involved with highway safety maintain that crossovers create accidents, are not necessary, and should be eliminated. When working on an accident study evaluating median type, it became obvious that at times median crossovers were causing frequent accidents, especially in some locations and certain situations.

Crossovers are locations on controlled access roadways where emergency and maintenance vehicles can cross the median to change their direction of travel. However, the motoring public also finds crossovers convenient for their use, even though the maneuver is illegal. This creates an accident producing situation. Accidents at median crossovers involving U-turning vehicles accounted for up to 25 percent of the total accidents on several road sections during some years investigated in this study. For a four year period involving the majority of toll roads and interstate roads in Kentucky, an average of five percent of all accidents were caused by vehicles using median crossovers.

The purpose of this study was to analyze existing crossover locations, usage, and accidents so as to develop criteria on the necessity for and the location of median crossovers. Primarily, three sources of information were used. An inventory of existing crossover locations was obtained to determine the prevailing philosophy, if any, on crossover locations. Secondly, a comprehensive analysis of U-turn accidents at median crossovers was performed. The accident analysis included special study of roads where U-turn accidents were most prevalent. To evaluate crossover usage, interviews were conducted with district highway engineers and questionnaires were given to all state police who patrol interstate or toll roads in Kentucky. The questionnaire also provided an opportunity for the state police to express their opinions concerning the location and necessity for crossovers.

Report Date

6-1-1969

Report Number

No. 278

Digital Object Identifier

http://dx.doi.org/10.13023/KTC.RR.1969.278

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