Between 2004 and 2006, the number of signalling failures, signalling downtime and the number of trains delayed as a result of signal failures all fell. RailCorp’s on-time running performance improved over the same period. The fall in failures is a clear indication of improved performance. Changes in the definition of on-time and to the timetable during 2005 and 2006 however make it difficult to determine whether improvements in response downtime and signalling delays are due to a true performance improvement. To build upon this strong base, RailCorp needs to determine with more confidence the number and duration of signalling failures the network can tolerate without impacting on service levels.