KiwiRail appears to be stating the obvious by saying there's an underlying fragility in Auckland's Rail Network.  

Some Auckland train services were cancelled through yesterday afternoon and evening, including at peak hour. 

Kiwi Rail, which owns the tracks, blames the high temperatures which reached 48 degrees in some places. 

That's despite the air temperature yesterday going no higher than 25 degrees. 

Auckland Transport's called the terminations 'enormously frustrating'. 

KiwiRail's David Gordon told Mike Hosking that it wasn't a "stop running trains" order, instead they put a speed restriction over four kilometres of rail.  

But he concedes that impacts the timetable. 

Gordon estimates six minutes per train, which has a compounding effect and makes it necessary to cancel trains.  

LISTEN ABOVE 

• "Really frustrating": Auckland trains cancelled due to heat