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MSHA Standards for a Road Haul

Haul roads are the backbone of any surface mining endeavor. Trucks use these roads to haul equipment, supplies and product to and from the mining site. The Mining Safety and Health Administration (MSHA) regulates the construction and use of these roads in U.S. mines to ensure safety for workers and for the general public that come into contact with the trucks using these roads.

  1. Sight Distance

    • Sight distance refers to the distance in front of the truck that the driver can see unassisted. The haul road must be designed so that the driver can safely stop and avoid obstacles. In bad weather and at night, the sight distance is decreased, requiring drivers to slow to accommodate the reduced sight distance. This distance is determined by how far the headlights provide illumination, roughly 250 to 350 feet. Sight distance at intersections is determined by the speed limit and grade on the road in all directions. In passing zones, the haul road is required to have a long sight distance along a minimal grade.

    Stopping Distance

    • Several factors affect stopping distance including driver perception, reaction time and the braking mechanism on the vehicle. Estimates to determine acceptable stopping distance are based on grade of the road and speed of the vehicle, and must take into account a 1 second response time on behalf of the driver. When following another vehicle, the driver must maintain at least a 200 foot distance on a level road or a 400 foot distance on a graded road. A good rule of thumb is to maintain at least two vehicle lengths' distance. The MSHA requires that all brakes on a vehicle using a haul road be maintained and any defects corrected immediately.

    Grades

    • The grade of the haul road must be compatible with the braking mechanism of the vehicles utilizing the road and should take into consideration the braking distance required by these vehicles. The percentage of grade is equal to the number of vertical feet that the road rises over a distance of 100 feet. The grade should be measured at every constant and varying segment of the road.

    Speed

    • The speed allowed on a haul road should be constant for as much of the road as possible and for all vehicles. The speed limit should decrease on downgrades, curves and areas where the sight distance may be impaired. The MSHA takes into account grade, visibility, road conditions, road width and congestion when evaluating the speed at which vehicles travel on the haul road.

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