Development of the QR Ballast Specification

The QR Ballast Specification has been continually developed to increase the service life of ballast and to stay abreast or ahead of increases in rail traffic volumes, maximum permissible axle loads and maximum train speeds. When the current version of the QR ballast specification was introduced in 1993, the maximum axle load limit on the QR network was 22.5 tonnes. In 2002 the maximum limit is 26.0 tonnes and increases to at least 30 tonnes are expected in the future. Ballast (like other track structure components) is expected to last longer and carry greater loads, and the progressive refinement of the QR ballast specification has been necessary to ensure this occurs. This paper covers the evolution of this ballast specification over the last decade. The proposed testing programs for determining future ballast test limits are also discussed.