Auckland Transport is trying to accelerate its rollout of electric trains, after continuing disruptions from diesel breakdowns.
Although August remains the official target for completing the rollout by extending electric trains to the western line, the organisation's board was told yesterday of efforts to bring the date forward.
Public transport group manager Mark Lambert said that would allow an earlier retirement of much of the increasingly troublesome diesel fleet, although 10 multiple-unit ADL trains would be kept and eventually refurbished for shuttle duties between Pukekohe and Papakura.
The Public Transport Users' Association is also campaigning for diesels to be retained for future rail services to the fast-growing areas of Kumeu and Huapai, even though Auckland Transport plans to stop running trains to Waitakere and making Swanson the terminus for the western line, once electric trains start running there.
Mr Lambert said there had been a high rate of diesel train breakdowns in January and February, which tended to cause greater disruption than previously, because of a higher frequency of services on the rail network.
"When it happens it has a bigger impact because of higher frequency," he said.
A broken-down diesel train blocking the tracks at Papakura on Thursday had a significant flow-on effect through the rest of the city's rail network.
His staff were working with passenger train operator Transdev on how to improve recovery times from such events, he told the board.
Last week's disruption was compounded when a second diesel train, sent to clear the first unit off the line, also broke down.
According to an internal Auckland Transport report, that caused the full or part cancellation of 32 services and delays to 64 others.
Although rail electrification will extend only as far south as Papakura, Mr Lambert said diesel shuttles would run between there and Pukekohe every 20 minutes.
The 1980s-era ADL diesels would be refurbished over the next two years, both mechanically and to upgrade their interiors "to provide a better customer amenity" and make them look more like the electric trains.
But Mr Lambert said the city's 1960s-vintage ADK trains had already been retired.
About 47 three-car electric trains have meanwhile arrived in Auckland from their Spanish assembly plant, leaving just 10 more to be supplied under a 57-train order costing Auckland and the Government about $540 million, including a 12-year maintenance contract and a $96m depot already built at Wiri.
KiwiRail has also spent about $600 million on electrifying and re-signalling Auckland's network.
But the Government rail operator is also receiving about $19.5m in track access fees from Auckland Council this financial year.
Auckland's electric trains
• 57 three-car units being rolled across an electrified network from Britomart to Papakura and to Swanson
•10 ADL diesel units to be retained for shuttle services between Papakura and Pukekohe