Enhancing freight railways for 30 tonne axle loads

An effective approach to decrease railway transportation costs is to invest in higher axle load and higher speed. Following a query from the Swedish iron-ore mining company LKAB, the railway infrastructure authorities of Banverket in Sweden and Jernbaneverket in Norway initiated a study of consequences and costs for an upgrading of axle loads from 25 to 30 tonnes (t) on Malmbanan and Ofotbanen. The influence of increased axle loads and improved bogie design on track structure degradation and costs for maintenance and reinvestments has been investigated. Full-scale field measurements of wheel-rail contact forces for the present iron-ore wagons with 25 t axle loads and for two types of prototype wagon with axle loads of 30 t have been performed. Computer simulations of dynamic wagon-track interaction and literature studies also provided information used in the estimation of track degradation rates. The total cost for upgrading the infrastructure to take 30 t axle loads was found to be lower than anticipated. As a consequence, five prototype wagons dimensioned for 30 t axle loads and radial self-steering bogies of the Scheffel HS type have been ordered and were delivered in early 1999 for tests on Malmbanan-Ofotbanen.