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~Y ~.. • • 87 IMPROVED HAUL ROAD BERM DESIGN By Gregory G. Miller,l Gary L. Stecklein,2 and John J. Labra3 INTRODUCTION Parts 55 and 77 of the Code of Federal Regulations, Title 30--Mineral Resources, require that "berms or guards be provided on the outer bank of elevated roadways" at metal and nonmetal open pit mines and at surface coal mines to prevent haulage vehicles from running off the haul road. The proper design and construction of haul road berms are not known, other than the current rule-of-thumb recommendation that berms be built as high as the axle height of the largest haulage truck using the haul road. However, interviews with mine personnel indicate that berms built to this height are ineffective in stop- ping runaway vehicles. A wide variety of restraint systems ate available. These systems are edge- of-road berms, guardrails, boulders, concrete barriers, median berms, and es- cape lanes. Mine operators overwhelming- ly prefer berms constructed of waste ma- terial because they feel that they are the least costly system since the waste material has to be transported along the haul road anyway. While the cost of the berm material may be negligible, addi- tional costs are incurred owing to con- struction time and additional road width necessary to carry the berm. To determine the proper design of safe haul road restraint systems, research was conducted by Southwest Research Insti- tute4 for the Bureau of Mines on design requirements for edge-of-road berms, guardrails, boulders, concrete barriers, median berms, and escape lanes. LOCATION OF RESTRAINT SYSTEMS Restraint systems such as berms should be used on all elevated roadways to pre- vent vehicles from going over the road edge embankment. The design requirements are dependent on the maximum possible runaway vehicle approach conditions. It is obvious that certain locations along the roadway such as downgrades and sharp turns must have restraint systems, but since mechanical failure, adverse weath- er, or human error can cause accidents, flat elevated roadways also must have them. METHODS OF VEHICLE-BARRIER INTERACTION ANALYSIS To determine Che effectiveness of vari- ous restraint systems, the following ap- proach was used: 1. Geometric-scale model simulations. 2. Full-scale field tests. 3. Computer simulation. The runaway vehicle approach conditions of 30 mph and a 30° impact were consid- ered maximum. While the speeds of most runaway haulage vehicles are lower, a berm designed to withstand these impact Mechanical engineer, Spokane Research Center, Bureau of Mines, Spokane, WA. 2Mechanical engineer, Southwest Re- search Institute, San Antonio, TX. 3Computer analyst, Southwest Research Institute, San Antonio, TX. 4Stecklein, G. L., and J. Labra. Haul- road Berm and Guardrail Design Study and Demonstration. Volume I (contract H0282028, Southwest Res. Inst.). BuMines OFR 188-82, 1981, 186 pp.; NTIS PB 83- 137091.