Auckland commuters left stranded by a stalled train network this morning have been forced to pay eye-watering Uber fares to get to work.

One woman coughed up $50 to get from Sandringham to the CBD - around four times the usual fare - as high demand caused Uber prices to surge.

Many also faced multiple cancellations from Uber drivers as they appeared to seek out more lucrative fares.

Train commuters were at a stand-still for over an hour as a signalling fault halted all services across the entire network.

Amid the central city chaos New Zealand Transport Agency was warning of heavy traffic on the motorways as thousands look to flee the city for Auckland Anniversary and the long weekend.

KiwiRail, which operates the signals, had trains moving on a restricted basis around 8.30am following the signalling fault that was noted at 7am this morning, chief executive Todd Moyle said.

"The cause of the initial fault is still being investigated. We are working to identify the cause."

Auckland Transport media relations manager Mark Hannan said the network's backup system had come into force meaning trains could be moved back to train stations and people were being let off.

"There is a backup system that allows trains to be moved to the nearest station."

The signals went out just after 7am, he said.

One commuter faced a 90-minute commute from Orakei to Britomart. Embarking at 6.50am they arrived at 8.30am.

There was plenty of capacity for the buses to cope with extra passengers from the trains.

Several commuters using Uber have noted price spikes and delays in pick up times.

One Uber user told the Herald her trip from Sandringham to the CBD cost $50, up from the usual fare of $10 to $12.

One woman travelling from Ponsonby into the CBD said she had trouble booking an Uber.

Every time she booked a ride the driver was attending a job far away meaning the wait time would be 15 to 20 minutes.

She also noted the price was almost double the usual fare, $12 up from $7.

One bus commuter said at 7.50am he had been stuck on a train in Drury for more than 30 minutes and was trying to make a university exam at 8am in the CBD.

Navin Raj posted to Twitter he had been in a stationary train outside of Newmarket Station for about 30 minutes.

Holiday congestion for Auckland was set to kick off from 9am this morning, NZTA said.

"Expect traffic to become heavy on #SH1 southbound at Takanini TODAY from 9am as holidaymakers leave the city for the long weekend. "