A derailed Kiwirail locomotive is expected to be put back on its tracks today.
The Wairarapa-bound train derailed north of Wellington on Thursday night.
It was knocked off the tracks by a slip as it came out of a tunnel at Maymorn, near Upper Hutt at about 6.15pm on Thursday.
It was carrying 300 passengers.
Kiwirail staff had hoped to put the locomotive back on the tracks last night, but were delayed because it was too dark and the ground was too soft, spokesperson Nigel Parry said.
Solid foundations were being constructed so two cranes – a 60-tonne rail crane and 200-tonne road crane – could lift the 85-tonne locomotive back on to the track this afternoon.
A track about 50 metres long had to be formed so the cranes could get close to the site.
"They're hoping that once the locomotive is free of the site there will be minimal track repair needed before they will be able to reopen the line," Kiwirail spokeswoman Ruth Larsen said.
The locomotive will be taken to Lower Hutt to be checked once it is freed.
When the incident happened, passengers were transferred to the train's rear three carriages and towed back to Upper Hutt before being transferred to buses.
Kiwirail aimed to have train services between Wellington and Wairarapa running again before Monday morning.