Vandals have cut almost 400 cables near Sandown Park station, bringing trains to a halt on part of the Cranbourne and Pakenham train lines.
Metro Trains chief executive Raymond O’Flaherty said offenders had in their “senseless” actions cut all signaling and other communications equipment at 1am on 1 March.
“I was taken aback by the extent of this brazen attack on our rail system.”
Eighty buses will replace trains between Oakleigh and Dandenong until “later this evening”, Mr O’Flaherty said.
Commuters should allow up for to 60 minutes extra.
PTV has suggested alternatives such as trying to avoid the congested afternoon peak.
Other alternatives are to catch the Glen Waverley line train with Route 902 buses to Springvale and Dandenong, or couple the Frankston line train with the Route 828 bus to Dandenong or Route 791 to Cranbourne.
The day before, passenger numbers in the Dandenong corridor soared by 30 per cent as workers returned in force to the CBD.
An extra 50 passenger trains were also servicing the lines from this week, running every 10 minutes in the morning and afternoon peaks.
“It’s not the journey we wanted to provide you with on that line. We wanted everything to go well as more and more people are going back to the city,” Mr O’Flaherty said.
“We apologise for this senseless act of vandalism.”
Victoria Police were investigating the “crime scene” in co-operation with Metro Trains.
“This was a senseless act of vandalism. We won’t tolerate this criminal behaviour on our rail service.”
Metro Trains had a “good track record” in bringing similar vandals to justice, he said.
Department of Transport’s head of transport services Nick Foa condemned the “wanton acts of destruction” that threw commuters into “chaos.
“It’s completely unacceptable.
“It’s a complete waste of resources and a complete waste of time for people trying to travel back to the CBD.”
Updates are on ptv.vic.gov.au. Real-time road conditions are at traffic.vicroads.vic.gov.au
