The Age: Metro moves to plug leaks in City Loop tunnels. Melissa Fyfe (April 25, 2012)
The tunnel walls of Melbourne’s City Loop will be injected with sealant in an attempt to stem serious water leaks and halt concrete erosion in the underground rail system.
The move follows a walk-through tunnel inspection by Alan Osborne, the man in charge of safety on the state’s rail system. Mr Osborne inspected the water leakage and concrete erosion in February, after The Age revealed the loop’s serious structural problems that had been ignored by successive state governments and train operators.
”There’s no doubt there’s a fair amount of leakage coming through,” said Mr Osborne, safety director at Public Transport Safety Victoria.
”It is a very corrosive environment. They just have to get the water stopped, basically.”
Metro will begin tackling the problem with a trial in June, when holes will be drilled into the tunnel walls and sealant pressure-injected into them.
The work will be funded by taxpayers from Metro’s maintenance budget. Metro and the government could not say yesterday how much the work would cost – it depended, they said, on how the trial went – but Mr Osborne estimated it would cost between $10 million and $15 million.
He said he was confident the measures would fix the problem. The acidic water leaking through the walls was causing two safety risks, Mr Osborne said. The water was corroding the electrical lines that power the trains. If they snapped, the trains would stop and passengers would have to evacuate. He said the water was also corroding the pads that bolt down the track sleepers, causing risks to the track’s stability.
Metro spokeswoman Geraldine Mitchell said the trial would take place in June, when other works were planned within the tunnel. ”It was Metro’s idea to trial this methodology based on advice from an independent tunnel expert who we engaged,” she said. ”This particular methodology has proven to be successful in other road and rail tunnels across Europe.”
Tom Sargant, Public Transport Victoria’s director of technical services, said the government would work with Metro to ensure it achieved ”a successful and cost-effective solution” to the water leakage and corrosion problems.
Mr Osborne told The Age he was satisfied with the tunnel’s passenger walkway – which has been criticised as being too narrow in the event of an emergency – and access to emergency exits. ”I actually think what we’ve got is better than many rail systems around the world,” he said.
Mr Osborne said he wanted Metro to bring its maintenance of the 30-year-old City Loop into its mainstream maintenance and safety systems.
”The tunnel itself has been maintained but it is showing its age a little bit.”
In September last year, The Age’s investigation into City Loop safety revealed drawings of fire-protected areas of underground stations had been lost, a CSIRO study of the smoke extraction fans found some were performing to a capacity of only 25 per cent, and that if a driver was incapacitated, there was no means of directing passengers to evacuate during a tunnel emergency.
The Age also reported that train drivers had noticed record levels of water seeping through the walls, along the tracks and on the emergency walkways. But at the time, Metro had said the water was not a safety risk.