| Popis: |
The one constant of North American railway heavy haul service is the quest for ever increasing axle loads. During the 1960’s, the maximum axle loads permitted in interchange increased from 23.9 tonnes (26.25 tons) to 29.9 tonnes (32.9 tons). This change resulted in an increase in rail wear and defect formation which, in turn, stimulated an increase in research and development activity to extend rail life in the heavier axle environment. Further the change to 29.9 tonne (32.9 ton) axle loads was made without a thorough examination of the increase in rail costs. To establish the costs associated with the operation of trains with heavy axle loads the Facility for Accelerated Service Testing, known as the FAST experiment, was begun on a 7.6 km (4.8 mi) track loop as a cooperative program between the Association of American Railroads and the Federal Railroad Administration at the Transportation Test Center near Pueblo, Colorado [1]. The FAST experiment and it successor, the Heavy Axle Load Program, have continued to quantify the system, including rail, costs encountered in operating trains with axle loads of 29.9 tonne (32.9 ton), and more recently, 35.8 tonne (39.375 ton) axle loads. Concurrently, major findings have been developed based on the operation of Australian iron mining railways which operate at axle loads up to 32.5 tonnes (35.7 tons) [2]. |
