The network’s track geometry standards were probably unsuitable for small-radius Broad-Gauge curves. A combination of track geometry irregularities had increased the probability of flange-climb at several locations on the small-radius Rushall curve.
The safety actions taken by MTM in combination with other actions pertaining to track maintenance should reduce risk associated with the safety issue.
Metro Trains Melbourne (MTM) has undertaken to review, and update as required, its network maintenance standards applied to small-radius curves and specifically maintenance tolerances on those geometric irregularities that increase the probability of flange-climb derailment.
The safety action taken by MTM in combination with other actions pertaining to track maintenance should reduce risk associated with the safety issue.
Modelling to update geometry tolerences
MTM is examining using modelling to simulate the risk of flange-climb derailment for different track geometry conditions on small-radius curves, and the potential for this modelling to support an informed revision of track geometry tolerances.
MTM has completed its review of track parameters on tight radius curves, and introduced tighter geometric standards for the maintenance of tight radius curves including maximum limits on the rate of change of gauge variation.
This was sufficient for the ATSB to close the safety issue at that point in time.
