This report documents research efforts that were undertaken to design, install, and test noise abatement devices for use on off- highway haul trucks operating in surface mines. The objective of the program was to reduce the environmental noise from haul trucks. The noise reduction devices that were developed utilized existing technology and were tested on a 50-ton haul truck. The work emphasized the reduction of noise emitted from the engine compartment, which included the use of side shields, sound absorbing material, improved radiator shroud design, and a modulating clutch fan. Noise tests were conducted using modified SAE test procedures for measuring sound levels around a stationary and moving machine, and inside the operator compartment. Test results showed a maximum of 4 dba reduction measured 16 ft from the truck. Interior cab noise was reduced 6 dba with the windows and vents closed.