MSHA's Haul Road Inspection Handbook (PH99-I-4) includes haul road width recommendations. First identify the width of the widest vehicle that will use that road. For example, this one is 12 feet wide. If we want a one lane road we begin with 12 feet for that lane. Now to make that lane safe we would add half of the width of the truck, in this example 6 feet, for an open area on each side of the 12-foot lane. This results in a 24-foot-wide lane. So the recommended width for one lane of traffic is two times the width of the widest vehicle traveling that road.