Major delays and train cancellations on four Melbourne rail lines could drag into the afternoon peak.
Rail services were thrown into chaos when a fire broke out in telecommunications equipment near Richmond railway station on Tuesday evening.
The equipment controls signalling, causing rail operator Metro Trains to cancel many services and leaving thousands of commuters stranded in Melbourne's CBD.
Frustrated passengers took to Twitter, using the hashtag #trainageddon to express their anger at Metro over the major disruptions.
Delays and cancellations continued for the Pakenham, Cranbourne, Frankston and Sandringham lines on Wednesday morning, and may affect afternoon peak-hour trains as repairs on damaged signalling cables continue.
Metro has asked commuters to allow extra time and be patient.
"We are very sorry and ask customers on the affected lines to allow extra time and be patient while we do our best to run as many trains and supplementary buses and work to resume services as quickly and safely as we can," Metro said in a statement.
All city-bound Frankston, Cranbourne and Pakenham services are running direct between Richmond and Flinders Street Stations, and there are reduced services on the Sandringham Line.
Metro said City Loop services for all other lines are operating normally.
Extra tram and bus services are running across the network.