A damaged cable is causing major delays on Auckland's southern and eastern train networks this morning.
This morning's delays come after hundreds of Auckland commuters were held up getting home last night after a signal failure cut stopped trains and left passengers stranded at Britomart Station.
Veolia Transport Auckland said a cable was cut overnight, affecting all train services between Pukekohe and Puhinui this morning.
"As a result limited services are running on this section of track and major delays are likely to be experienced as the peak travel period approaches," Veolia said in a statement.
"This affects all Southern Line passengers and delays and full capacity carriages are expected on the Manukau/Eastern Lines. These services will be running as they can and not on the published timetable. Western and Onehunga Line services are not affected and are running to timetable."
Commuters are advised to seek alternative transport.
Veolia said some taxi shuttles were operating between Pukekohe and Papakura but customers travelling between these two stations were advised to seek alternative transport where possible, while rail replacement buses were being arranged from Papakura towards the city.
Last night's fault happened about 6.30pm at the end of peak-hour traffic, causing people to pour out of the station searching for buses and taxis. An announcement at Britomart said services had been stopped due to a signal failure in Wellington.
However, Kiwirail said it was an Auckland-based problem -and not a repeat of the debacle in April which crippled Auckland's rail network.
Kiwirail spokeswoman Kimberley Brady said the technical fault happened on the Auckland rail network system and an investigation had begun into what caused it.
She said Kiwirail was happy the system was restored within half-an-hour, "but we'll obviously investigate the cause to try and make sure it doesn't happen again".
A spokeswoman for Auckland rail operator Veolia said train control asked them to halt all services while the problem was fixed.
"Passengers that were waiting at stations were advised they could use their AT Hopcards and rail tickets on normal bus services. Obviously, due to the time of day we couldn't organise rail replacement buses."
The outage affected the southern and eastern lines, while western line trains were operating, although with delays.
KiwiRail today apologised for the disruptions.
It said today's delays were caused when a telecommunication cable was damaged overnight by contractors working on the rail electrification project.
KiwiRail chief executive Jim Quinn said his organisation had launched investigations into both incidents.
"We understand how much frustration this disruption will have caused people who rely on the trains, and we sincerely apologise for that."
Work was underway to repair the fibre optics cable damaged near Papakura as quickly as possible, so normal rail services could be restored.
Mr Quinn said KiwiRail would be working to understand how the incident occurred while works was being done on installing the overhead masts and wires required to power Auckland's new electric trains.
Technical teams were also working to understand the cause of last night's signalling fault, Mr Quinn said.
"It was a local Auckland fault, and with complex equipment such as that it can take some time to pinpoint the cause."