(file image) Photo: RNZ / Jessie Chiang
Auckland trains are facing delays and cancellations for a second day in a row.
Auckland Transport said trains on all lines were running at "reduced frequencies" because of KiwiRail train speed restrictions.
"Scheduled buses are accepting train tickets to and from impacted stations. Check Train Line Status before you travel."
The agency said trains on all lines would be reduced with at least 19 cancellations during peak hour, from 3pm.
Auckland Transport public transport director Stacey van der Putten said the disruption to the city's train network was likely to continue.
"It may well be the new normal for the next month or so. What's important to understand is that trains are running - it's the key message here. Trains are running, on some lines there might be a slightly reduced frequency."
KiwiRail imposes speed restrictions when the tracks overheat, forcing trains to travel at half speed.
Eighty-eight trains were cancelled across Auckland's commuter network on Monday due to a range of problems - not just the heat.
While some trains could not run because of speed restrictions imposed to stop tracks buckling, Auckland Transport said other trains were cancelled due to crew shortages and a breakdown.
Mayor Wayne Brown is demanding the city's transport bosses explain why the trains keep being disrupted.
KiwiRail said it was working hard to upgrade train tracks so they would not be as affected by heat restrictions.