Potentially dangerous cracks have been found on 18 Metro rail carriages, forcing the state government to spend millions on replacement parts for Melbourne's ageing Comeng fleet.
Metro has begun repair work on 18 carriages where cracks have been identified, although it believes any patch-up job is likely to be temporary. The cracks are also likely to affect more of Melbourne's train fleet, Metro said in an internal document, potentially cutting short the damaged carriages' service life.
The cracks are confined to the bogies of some of Metro's Comeng trains, which began to come into service in 1981. The trains are due to be taken out of service in 2024.
Bogies are part of the load-bearing structure beneath a train carriage, so any severe cracking is a threat to passenger safety and could potentially derail a train.
In January, V/Line pulled 22 of its older carriages out of service for repairs due to cracked bogies. It took until June for the first of them to be returned to service.
A leading rail engineer said passenger safety would depend on how closely Metro monitored the cracking. ''It's very unlikely to end up in anything catastrophic,'' he said. ''It's always possible, but it really goes to the strength of Metro's surveillance, how closely they're inspecting them.''
The cracking in Metro's trains was identified late last year, according to an internal report written in March. It warns that although the damage is confined to just 18 trains, it is likely to spread.
''Given the nature of the failure, the cracks can be expected to spread across the population of LHB bogies,'' the document states. ''A weld repair procedure has been developed. Welded repairs are at best likely to be a stop-gap measure as the area around the weld will be affected by heat, creating conditions for further failures. Whether we can get through to the proposed end of life of these trains  is problematical.''
Any carriage with a crack more than 80 millimetres long will be taken out of service for repair, and any bogie with a crack greater than 120 millimetres is recommended to be scrapped, the document says.
The problem is being caused in part by the condition of the tracks on the metropolitan rail network.
Transport Minister Terry Mulder said the cracking was confined to 30 six-carriage Comeng trains with disc brakes and fabricated bogies. Four bogies have already been replaced, he said.
''Public Transport Victoria is finalising discussions with Alstom to supply 100 replacement bogies along with options for up to 75 more at a total cost of more than $5 million,'' he said. ''This will extend the life of these Comeng trains if necessary, although the Coalition government has already ordered or placed in service 15 new six-carriage suburban trains and will continue to consider the renewal of Melbourne's train fleet.''
Given that we can't even seem to phase out the remaining Hitachi, we are going to have a major train shortfall in the medium-term. Note the article states the issues are with trains with disc brakes; these are the second series of Comeng.