The Johnsonville railway line will be closed most nights until December for an upgrade to tunnels on the track.
Ontrack will begin work on Monday night in preparation for enlarging seven tunnels on the 10.4km line, to accomodate bigger trains due to arrive in two years.
From Sunday until Thursday, the line will be closed from 8pm and re-open by morning. Buses to and from Wellington will be provided for commuters.
The actual widening and lowering of the tunnels will happen over the Christmas period.
The first electric train for commuters ran on the Johnsonville line on 2 July 1938. The line was built by the Manawatu Railway Company in 1886 and was taken over by the New Zealand Government in 1902.