Introduction Of Heavy Axle Loads By The North American Rail Industry, 1990 To 2012

Abstract

The Association of American Railroads initiated the Heavy Axle Load (HAL) Research Program in 1988 in order to “provide guidance to the North American railroad industry about whether to increase axle loads and to determine the most economic payload consistent with safety(1). The research, which is still on-going, has demonstrated the technical feasibility and economic desirability of increasing axle loads and the ability of technology to mitigate the adverse effects of heavier loads. As a result of the initial phases of the HAL Research Program, the industry decided in 1991 to accept cars with 286,000 lb. gross vehicle weight (GVW) in interchange service. Since then, more than 90% of all bulk equipment acquired has been rated for 286k GVW. Today, nearly 100% of coal traffic and approximately 30-40% of general freight moves in 286k loads. Annual benefits of HAL operations to railroads, suppliers, and their customers now exceed $1 billion. Benefits include reduced capital and operating expenditures for bulk equipment, increases in net tons per train mile, better fuel efficiency, and increases in line capacity. Further benefits are now being realized by the introduction of shorter cars that retain the 286k GVW limit, while gaining most of the cost and capacity benefits of heavier cars. Technological improvements resulting from the HAL research program have been critical in enabling the industry to reduce costs of 286k operations. Some of the most important advances have been the use of better metallurgy, grinding and lubrication to control rail fatigue and extend rail life. Other technological innovations have extended the design and the life of turnouts and wheels. Bridge costs did not increase as much as was expected, in part because of technological developments and in part because of a better understanding of the ability of track and structures to withstand HAL loads. This paper begins by reviewing the motivation for and the results of the initial HAL research, including a summary of the expected costs and benefits of HAL implementation. It then documents the rate of implementation by showing the increases in average tons per carload for bulk commodities between 1990 and 2012. The greatest benefits have been achieved for coal, as this is the dominant bulk commodity handled by rain and the average tons per carload increased from less than 100 to more than 115 over this period. Estimates of benefits and engineering costs are based upon the framework established in the economic analyses of Phases I and II of the HAL Research Program and the results of subsequent studies related to HAL implementation.