Simulated median plantings were installed on selected portions of two Chicago expressways to determine whether such a means of providing roadway delineation would significantly reduce the frequency of vehicle encroachment on the median. A complete record of encroachments was obtained during the same portion of the previous year. There was a significant reduction in the frequency of encroachment on the medians of both expressways, with the greatest reductions occurring on or near curved alignment where the hazard of headlight glare from opposing vehicles had previously been greatest. However, no attempt was made to measure the relative magnitude of the several roadway delineation benefits that were assumed to have contributed to the observed reductions. The findings suggest the possibility of substantial improvement in the safety of divided highways through the development and use of median plantings appropriate to the needs of the driver under the various conditions imposed by roadway characteristics, driving conditions, and surrounding land use.
Abstract