The 4-car electric unit that was derailed after it hit debris caused by a slip a kilometre south of Paekakariki. Photo / Mark Mitchell
Waka Kotahi NZTA Regional Maintenance and Operations Manager Mark Owen said a temporary speed restriction was in place for southbound traffic on State Highway 1.
Motorists should still expect delays and allow extra time for their journeys, he said.
"There has been a lot of disruption on the Wellington state highway network today due to this morning's slip and train derailment, and we'd like to thank everyone for being so patient and understanding."
Waka Kotahi urged motorists not to use the Paekākāriki Hill Rd as it was a more challenging route in difficult weather conditions.
Southbound traffic backed up on State Highway 1 earlier today. Photo / Mark Mitchell
Vehicles coming off Paekākāriki Hill Rd and on to State Highway 1 would worsen congestion and delays, the transport agency advised.
Contractors are scheduled to return to the State Highway 1 slip site at 9pm to deal with culverts that were not able to be cleared before the road was opened to traffic.
Stop/go traffic management will likely be in place while this happens.
Metlink General Manager Scott Gallacher said it wasn't going to be ease to resume normal trains services on the Kāpiti line and it would take time.
KiwiRail will use a heavy-duty crane to lift the passenger train units back on to the track, Gallacher said.
They will then be moved to Paekākāriki for inspection.
The site of the slip will have to be cleared and the line made safe before it becomes operational again.
"All of this is heavy, time-consuming work and it's therefore unlikely that the line will open until tomorrow morning at the earliest", Gallacher said.
"To be on the safe side we recommend that the people of Kapiti check before they travel and be prepared to work from home to avoid congestion."
