Auckland's new electric trains are back running between Onehunga and Britomart, despite a continuing mystery over a power failure which knocked them out of action last week.
The "intermittent" failure, which knocked out four trains in one hit on one day and then struck again the next, prompted Auckland Transport to replace them with old diesel units during a frantic search for the cause.
A spokesman said yesterday they had been returned to service on Thursday but, when questioned by the Weekend Herald, acknowledged the problem had yet to be fully diagnosed - let alone fixed.
"The fault is a high-frequency voltage spike ... and appears to be associated with interaction between the trains and the power supply system," he said. "Auckland Transport is working with KiwiRail on testing the EMUs [electric multiple unit trains] with alternated sections of the network livened."
The spokesman said on Tuesday that the council body still hoped to extend electric train passenger services to the Manukau-Britomart run via Panmure and Glen Innes on the eastern line on August 17.
