'It's only getting worse': Commuter chaos continues through peak hour

Sydney commuters were told to leave work early or stay back late after a single train caused massive delays and chaos on the city's rail network.

A train on the north shore line needed mechanical repairs on Friday after an open train hatch was spotted by the driver about 5.30am at Town Hall.

The flow-on disruptions amazingly extended into the evening peak with city workers facing a chaotic train system and gridlocked road network.

Passengers were held up at Town Hall after 5pm as staff closed ticket barriers with long queues forming as commuters waited for their turn to enter the station.

Video shot at Central Station and posted to Twitter about 4.30pm showed a platform crammed with people trying to beat rush hour.

Sydney Trains chief executive Howard Collins said the hatch that started the chaos on Friday morning was very close to 1500 volts of direct current power and could have caused days of damage if left unchecked.

"It could have brought all the wiring down in the city ... we could have gotten stuck over the Harbour Bridge," he told reporters.

Commuters were left languishing on trains or queuing for buses for hours as officials worked to repair the fault.

Some were even told to try walking across the Harbour Bridge instead of waiting.

Sydney Trains ahead of the evening peak warned services across the network were still recovering and wouldn't run on time.

Frequent train services were to be maintained but commuters were advised to check the latest service information and either leave early or delay their trip.

One on Twitter was shocked by the time it had taken to fix the fault.

"Obviously 11 hours isn't enough time to fix a single 'minor' issue on one train near one station," they wrote.

"RIP Sydney commuters today. I may not see my husband again until midnight," another said.

One said on Twitter the chaos “is only getting worse”.

Hordes of commuters are seen standing on a train platform at Town Hall during the delays.
Commuters are seen at Town Hall train station in Sydney during train chaos. Source: AAP

Vehicle traffic in and out of Sydney's CBD was gridlocked after 5pm.

Mr Collins apologised for the widespread delays but believed his team made the right call in stopping the train.

What caused the hatch to open is being investigated but early signs point to wind or a tree branch hitting the train.

In order to fix the hatch, power to the line had to be switched off – which involved sending workers down tunnels to pull isolation switches.

A notice board at a train station says certain platforms are closed due to mechanical repairs.
Train platforms were closed and many services cancelled due to the fault at Town Hall. Source: AAP

Mr Collins revealed those switches were put in place in the 1920s or 30s and were "almost Frankenstein in their look".

"It is a failure of the way our system is built that one train can stop the entire network," he said.

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