The scheduled ultrasonic tests conducted in November 2013 on the 80 lb/yd rail between Northgate and Alice Springs had been ineffective in detecting and quantifying the significant defects present at 1036.541 km and 975.244 km locations.
The ATSB is satisfied that the action taken by Genesee & Wyoming Australia addresses this safety issue.
GWA advised that the continuous detailed ultrasonic inspection frequency of 80 lb/yd rail has been increased to a minimum of four inspections per year and a programme to replace all 80 lb/yd rail is being evaluated.
Following the derailment, GWA applied additional initiatives (reflected in the following statement) designed to mitigate risk associated with train operations over the lighter weight rail.
Since the derailment we have decreased the speed to 40km/h for passenger services and 50km/h for freight services over the entire 80lb/yd rail length. We have also increased track patrols and run the 80lb/yd section six times a week. This ensures that we inspect in front of every passenger service and a majority of our freight services.
The ATSB recognises that slower train speeds over the 80 lb/yd rail will reduce the dynamic forces transferred through the rail, in doing so, lessening the risk of rail failure. In addition, the quadrupling of detailed ultrasonic inspections and the increase to six track patrol inspections per week is more likely to identify rail fracture precursory defects.
