Metro took the unprecedented step of cancelling trains in advance so passengers who regularly catch those trains could make other plans, it said. Metro spokeswoman Larisa Tait said the speed restrictions would also cause some delays. Flashback to 2009, when Connex workers used water to cool buckled tracks at Jolimont. "We are not expecting all services to run on time tomorrow," Ms Tait said. "We anticipate that some services will run late due to the speed restrictions in place, as trains can only travel at 80km/h on parts of the network where they usually travel at 110km/h." The heat-related cancellations in Melbourne contrast with Perth's recent experience, in which not a single train was cancelled due to the heat, despite a string of days above 40 degrees.

Transperth spokesman David Hynes said no trains were cancelled. "Perth is less affected than other states because the bottom line is we have a better rail network, although it's smaller," Mr Hynes said. "We have concrete sleepers throughout our entire network, whereas Sydney and Melbourne are still mostly wooden sleepers which are more prey to heat." Peter Newman, Professor of Sustainability at Curtin University in Western Australia, said extremely hot days would become more frequent in Melbourne due to climate change, and the city needed to modernise its rail network to cope. Doing so was not complex, it just required investment, said Professor Newman, who is also on the advisory board of Infrastructure Australia. "Perth had no cancellations because the rail has been built to cope with these extremes," he said. "It's just a simple engineering task." Metro said it had a large program in place to make the network more resilient to heat. This included "restressing" the tracks to prevent them buckling, ensuring track ballast was at the correct depth and compactness, and cleaning out train air-conditioners. It had also replaced more than 50,000 wooden sleepers this year.

Yet its decision to cancel 48 services could trigger compensation claims from some passengers at the end of the month, should Metro miss its monthly reliability target. Public Transport Victoria said it would treat them as ordinary cancellations. Metro must run 98 per cent of trains under its contract with the government. "On an average weekday, we run approximately 2280 services, meaning the number of cancelled trains equates to 0.7 per cent tomorrow and 1.4 per cent on Friday," Ms Tait said. A transport engineer with good technical knowledge of Melbourne's system said ageing and inadequate traction power, which powers trains along the lines, was also to blame for chronic delays on hot days. Metro had this week deliberately "thinned out" its timetable in response, he said. Loading "The equipment that is used in the substations is very old," he said. "There is a progressive upgrade but the equipment gets hot and becomes less reliable and you find that there is less ability for a particular line section to accommodate a certain number of trains."

Tony Morton, the Public Transport Users Association president, said Metro was less culpable for the cancelled services than successive state governments that had failed to properly maintain and renew the system.