Sydney commuters stuck in train underground for two hours after 'signalling' issue

Sydney commuters were stuck in a train for about two hours after the service was affected by a signalling communications issue.

A train on the North West Metro Line came to a sudden stop between Cherrybrook and Epping about 8.15am today.

A buzzing sound reverberated through the entire train, spooking the hundreds of passengers.

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"We were on our way to the airport, missed my flight," Halle Farr told 9News.

"It broke down, it was really loud, the aircon turned off, it was so scary.

"They just kept repeating the same thing like stay calm, we know it's broken down and that it'll be fixed soon."

Authorities worked to find out what caused the outage but were unable to resolve it until about 10.30am.

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After the train finally made it to Epping hours later, the entire station was shut down and commuters were redirected onto replacement buses.

By 11am, the platforms were reopen and trains were running again.

Metro Trains Sydney acknowledged the effect the issue had on passengers, apologising for the major delays caused.

"We acknowledge the time taken to resolve the issue is not good enough and we will continue reviewing our incident processes," a spokesperson said.