State Highway Engineer

Raised pavement markers have been installed on approximately 1,500 miles of highways during the past five years. Installations have included supplements to lanelines and edgelines, replacement of lanelines with raised markers, and in gore area delineation. In addition, use of markers as a traffic control measure at lane drops (Research Report No. 384) was the subject of a study in which the effectiveness of reducing erratic movements was shown. Another study (Report No. 425) dealt with the operational applicability of raised markers and their effectiveness with respect to brightness "'1d durability. This study, to evaluate raised markers at high-hazard locations, was conducted in cooperation with the Federal Highway Administration in accordance with Basic Agreement DOT-FH-11-9279 (copy included in the Appendix). A series of horizontal curves on US 68 in Mercer County and a narrow bridge over the Kentucky River on KY 627, near Boonesboro, were the sites of the instalhitions. Visual observations, speed data, encroachment data, and accident data were used to evaluate effectiveness. Because pressure sensitive, markers failed to adhere to the pavement and because of snowplow damage, five installations were made at the two sites between October 1977 and August 1978. Considerable emphasis was placed on documentation of the markers during various light and weather conditions. Results provided sufficient data to support recommendations for delineation at similar sites on th