Run-Off-Road Collisions: Appendix 1

Description of Pennsylvania DOT Strategies For Reducing ROR Harm

Emphasis Area
Run-Off-Road Crashes

Strategy Number and Name
Multiple strategies including bicycle-tolerable rumble strips, edgeline rumble strips, innovative curve markings, and delineation of hazardous trees and utility poles on two-lane roads.

Agency and Jurisdiction
Pennsylvania DOT.

Problem(s) Identified
Increased rates and frequencies of run-off-road crashes on two-lane roads.

Goals and Objectives Established
Reduce these crash rates, while continuing to better serve other users such as bicyclists.

• Bicycle-tolerable rumble strips—Working for the Pennsylvania DOT, the Pennsylvania Transportation Institute conducted research on alternative designs to alert motorists while being disruptive to the bicyclist. The resulting design, which is used on shoulders at least 6 feet wide, is a 3/8-inch-deep cut that is 5 inches wide and 16 inches in length. For 55 mph and higher speed limits, there is a 7-inch space between cuts. For speed limits of less than 55 mph, there is a 6-inch space between cuts. The rumble strips begin 6 inches off the edge of the travel lane. (See typical drawing below.)
• Edgeline rumble strips on two-lane roads with 4-foot shoulders—Pennsylvania is trying experimental installations of rumble strips on the edgeline, rather than further out on the shoulder. (If the edgeline is on the longitudinal pavement joint, the rumble strips are located inside rather than on the joint.) These are milled–in continuous "bicycle-tolerable" cuts which are 7 inches apart, 5 inches wide and 3/8-inch deep. They are approximate 6 inches in length (i.e., 2 inches greater than the centerline width).
• Slow/arrow curve warning treatment to reduce speeds at hazardous curves—This experimental treatment consists of the word "SLOW" in 8-foot-high white letters, a white 8-foot-high left curve arrow, and an 18-inch-wide white line perpendicular to the road at the beginning and end of the text/symbol.
• "Object Delineation" (Delineation of hazardous trees and utility poles)— Pennsylvania DOT is delineating potentially hazardous objects in an experimental program targeted to locations with high ROR utility-pole and tree-related crash frequencies (particularly at night) where it was not feasible to remove or relocate the object either due to budget constraints or to the object being on private property. The tree or utility pole is marked with a 4-inch round of reflective tape. One round is used on each tree and each utility pole, except for poles at intersections where two rounds are used.

Summary of Implementation Effort

• Bicycle-tolerable rumble strips—These are being implemented at selected locations in the summer 2001.
• Edgeline rumble strips—These are being installed on several sections of two-lane road with 4-foot shoulders in at least two districts.
• Working with the Insurance Institute for Highway Safety, Pennsylvania DOT installed an experimental warning design on the pavement at six curves. (The same treatment had been installed earlier at one site in Northern Virginia.) In 2001, the marking was to be implemented at 200 sites statewide. The treatment is now being tested in 11 districts in over 50 counties.

Summary of Results

• Bicycle-tolerable rumble strips—Current installation, with no results at this time.
• Edgeline rumble strips— Pennsylvania DOT has chosen locations (high hazard sites) and began to install these in two pilot districts the spring and summer 2001.
• Slow/arrow curve-warning treatment—At the six curves where it was implemented, a before/after study of effects on vehicle speeds showed that these pavement markings had little effect on the average speed and the 85th percentile speed. However, the 95th percentile speed was reduced significantly.
• "Object Delineation"—This treatment has only recently been implemented and has not been evaluated at this time. Thus, it is clearly an experimental treatment.

Mike Baglio, Pennsylvania DOT Bureau of Highway Safety, 717-705-1706.

EXHIBIT 1. Typical Drawing Detail for Bicycle Tolerable Shoulder Rumble Strips for Non-Interstate and Non-Expressway Use on Roadways (Source: Pennsylvania DOT)