Lane departure has been shown to be a major cause of serious traffic crashes. Installing a rumble strip on the shoulders of two lane roads provide drivers with an audible warning that they are leaving their lane of travel. Painting the edge line on the rumble strip has the possible benefit of providing more wet, nighttime delineation through the portion of the edge line painted on the sloped portion of the groove. The objectives of this study were to: a) monitor the initial installations of rumble stripes and b) evaluate the results of rumble stripe installations.

Ten rural, two-lane road locations were selected by the Kentucky Transportation Cabinet across the state for the initial installations. A total of 67.7 miles were included with the installations completed in the summer of 2009. The locations were selected after a review of crash records.

The rumble strip had a width of 12 inches and a length of 7 to 7.5 inches. The depth was between ½ and 5/8 inch. The rumble strips were placed on 12 inch centers. The four inch wide white edge line was placed in the leftmost edge of the rumble strip adjacent to the travel lane.

The total pavement width (including the width of the paved shoulder) varied at the locations from a minimum of 22 feet to a maximum of 27 feet. In some instances the rumble strip was placed at the edge of the pavement while there was pavement outside the rumble strip at other locations. There was a problem encountered at only one of the ten locations. The issue related to a narrow lane width which resulted from placing the rumble strip with 18 inches of pavement outside the rumble strip. There were positive comments at all the other locations.

The crash data show that the most common type of crash before the installations was a single vehicle type of crash. This is the type of crash that shoulder rumble stripes are designed to reduce. There was a very small percentage of opposite direction type of crash.

The results of the current evaluation support additional installations of rumble stripes. The crash history at the original installations will be monitored. Recommendations relating to the installation procedure were made to consider for future rumble stripe installations.

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, nor the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names or trade names is for identification purposes only and is not to be considered an endorsement.