When marginal-quality rock is encountered in Southeast Alaska, the rock often does not provide adequate support for truck haul. The road surface tends to rut and the rock continually breaks down after heavy repeated wheel loads combined with wet conditions. This process reduces the gravel to fine silt and clay-sized particles that will not support construction vehicles. The traditional solution has been to blade this material off the road and haul additional higher-quality rock to support the traffic. This procedure results in higher costs and additional stream sediment. By using radial tires with lowered tire pressures, the road surface became more compact with repeated wheel loads. This result has produced large savings, exceeding $500,000 on one project, and this concept is expected to provide future contract savings for road building and logging activities.

High-quality, durable rock is available for most road contracts in Southeast Alaska, but in some areas only poor-to marginalquality rock borrow materials are available for road construction. This fact can result in a road surface too weak to support truck haul, especially in the wet climate and soft, highly organic. subgrade conditions encountered on the Tongass National Forest. Immediately after placement, the marginal-quality rock breaks down with repeated applications of heavy construction traffic, resulting in deep ruts within the wheel path. The conventional solution typically involves blading the decomposed aggregate slurry off the roadway, and importing better-quality materials from a distant source. This solution increases construction costs significantly and also increases the amount of potential stream sediment delivery. An alternative solution is described that was used on a timber access road construction project, the Toncan timber sale, that used reduced constant tire pressure and radial tires. Although conditions described here are representative of southeast Alaska, they may also apply to other areas where poor-to marginal-quality road surfacing material, combined with high rainfall, are encountered.