Brake failures on large trucks descending steep grades in the mountains of North Carolina have annually accounted for a large amount of fatalities, injuries and property damage. On February 1, 1974, the North Carolina Division of Highways opened a runaway truck escape ramp on a 5 mile, 6-8 percent grade section of U.S. 70 between Ridgecrest and Old Fort, N.C. After the opening of this escape ramp, it was found that the ramp was used so frequently that an additional back-up ramp was constructed just downhill from the first ramp and made operational on December 15, 1975.

The ramps are constructed of sand and are approximately 350 feet in length, rising in elevation from 0-10 feet above the roadway so as to present the truck with a level (0 percent grade) runway. The runway is approximately 30 feet wide at the mouth and widens to approximately 45 feet at the far end. The surface has been shaped into irregular surface mounds approximately 3 feet high on 15-foot centers.

An accident study has shown the escape ramps to be highly effective. In addition, a photographic surveillance study of actual truck involvements using two movie cameras with wide angle lenses was recently undertaken. A study of these filmed involvements will aid engineers in determining the most effective design characteristics of future escape ramps. This paper will describe North Carolina's experience with these truck ramps.