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96 <br />70 <br />60 <br /> <br />Soil test bed <br />Scale vehicle <br />~d <br />L <br />~ 50 <br />} <br />F <br />U 40 <br />O <br />J <br />W <br />> 30 <br />U <br />Q <br />a 20 <br />10 <br />0 <br />Entry ramp <br />' KEY <br />Sandy material <br />• Theoretical-100-pct load <br />• Model tests-120-pct load ~ <br />• Model tests-60-pct load <br />• Model tests-0-pct load <br />Ascent angle (8 )= 20° <br />Soil depth (d)= 2x(axle height) <br />Load= Vehicle carrying load <br />Vehicle base carrying load <br />10 20 30 40 50 60 70 80 90 100110 120130 <br />VEHICLE STOPPING DISTANCE, ft <br />FIGURE 5. - Stopping distances for an 85-ton haulage vehicle on an escape lane impacting at <br />carious velocities on a 20-pct positive grade. <br />SUMMARY <br />Edge-of-road berms, guardrails, boul- <br />ders, concrete barriers, median berms, <br />and escape lanes were evaluated for their <br />ability to redirect, restrain, or roll <br />over onto the roadway a runaway haulage <br />vehicle. Geometric-scale model simula- <br />tions, full-scale field tests, and com- <br />puter simulations were used, where possi- <br />ble, to evaluate each restraint system <br />design at vehicle approach conditions of <br />30 mph, 30° impact, and carrying a full <br />payload. <br />The results of this study indicate that <br />the construction requirements of berms <br />can be directly related to the size of <br />the largest vehicle to be restrained, and <br />the composition and state of compaction <br />of the berm material. For significantly <br />compacted berms, it is recommended that <br />