Some train services have been delayed or cancelled again in Tāmaki Makaurau/Auckland on Tuesday, due to overheating tracks.
As a result of trains having to go slower, trains on all lines are running less frequently, Auckland Transport (AT) said on X.
"Due to KiwiRail train speed restrictions there will be some delays and cancellations to services today," the agency said.
It's the second day in a row of disruptions, after dozens of services were cancelled on Monday, some also due to heat.
AT's public transport director Stacey van der Putten said in a statement the organisation was disappointed with the disruption yesterday, due to the hot tracks.
"These speed restrictions would be unlikely to be needed today if the Auckland rail network was not vulnerable because of numerous known faults," she added.
Van der Putten told Newshub a week ago that a whopping 35 percent of cancelled trains in January were due to overheated tracks.
Jon Knight, KiwiRail's general manager metros, said yesterday that trains going too fast can move tracks (rails) out of place when they're above a certain temperature, about 40C.
"It means that trains have to travel slower over these areas, due to the risk the track may have been misaligned by the high temperatures expanding the rail length."
Trains can derail if they go too fast across overheated tracks.
Also on Monday, the mayor of Tāmaki Makaurau/Auckland sent a stern letter to the bosses of the three organisations involved in the city's train network.
Wayne Brown wrote to Dean Kimpton of AT, Peter Reidy of KiwiRail, and Martin Kearney of Auckland One Rail about recent train issues.
"The frequent disruptions on the Auckland train network have become unacceptable," the letter began.
Communications between the three agencies was "muddled", Wayne added.
"I'm asking you three to meet with me to explain how these disruptions keep happening, and what is being done to both fix it and quickly restore public confidence."
He hinted he wanted to meet the three bosses this week, along with Transport Minister Simeon Brown.
Simeon told reporters he'd called KiwiRail on Monday about the overheating tracks.
"Incredibly concerned and frustrated on behalf of Auckland commuters," he said.
AT asks commuters to check the status of their train line on the AT Mobile app before travelling.
