Johnsonville Line

We're starting to turn our focus to the Johnsonville Line where we'll be:

  • Renewing traction power overhead line systems.
  • Renewing sleepers within all seven tunnels.
  • Slope stability improvement Ngaio Gorge.

These works are expected to be done in phases and completed in 2022.

Replacing the overhead electrical system

We’re upgrading the overhead electrical systems between Ngaio and Johnsonville. To do this we are replacing around 100 of the old wooden overhead masts with steel poles.

The systems were first installed in 1938 and while they have been well maintained they are well overdue for an upgrade. Since 2007 we have been progressively replacing the system as it reaches the end of its useful life.

The modern, traction system will mean more reliable train services and provide a platform for increased services.  It will also require reduced maintenance and make our rail network more resilient to future seismic activity.

The new infrastructure will be installed in different places and look a little different.

The replacement happens in three stages:

  1. Building the foundations for the new steel poles.
  2. Installing the new masts. 
  3. Hanging and connecting the lines.

Once the new system is up and running we’ll remove the wooden masts.

This work can only be done while the power system is turned off and no trains are running

It takes place mostly at weekends to reduce disruption. Some of the machinery we need to use will create some noise and vibration. There’s also a chance that our work produces some dust.

We do our best to keep all this to a minimum. Even so, there could still be some disruption.

We apologise for this, and we’re grateful for your patience while we get this done.

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Tunnel and slope works

Track upgrades within the tunnels

We’re doing a full sleeper replacement in all seven tunnels along the line. This work can only be done when no trains are running.

The seven tunnels are between 100 - 200m long, and we’re replacing around 1600 wooden sleepers with more resilient concrete ones.

Improving approaches at Ngaio Gorge

We’re also reinforcing the steep slopes that line the approach to the tunnel in the Ngaio Gorge. This work is underway and sees us drilling into the banks and installing steel pins to anchor safety netting into place to reduce the chance of slips.

The team are abseiling down from the top of embankments from heights of ten metres to complete these works. The teams will be drilling 200 holes up to 4m deep to install steel anchors to attach metal netting that will stabilise the slopes.


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Working in tunnels

Tunnels access can be tricky when trains are running 18 hours a day.

Got a query about this project

If you have any queries or concerns about our activity please contact us on:

Travel while work is underway

Buses will replace trains when they can’t run on the tracks due to construction. Visit MetLink to find out about changes to passenger services in your area.