KiwiRail: Kaimai Tunnel upgrade requirements to be identified

Published on : Wednesday, October 8, 2014

KiwiRailLogo-300x63KiwiRail has begun assessing what is required to refurbish the rail track and tunnel floor of the Kaimai Tunnel – its first major reconstruction since opening 36 years ago.

Once that assessment is complete work will take place over the coming five to ten years to upgrade the 8.9km long tunnel to future proof the busy transport linking the Bay of Plenty to the Waikato, Auckland and beyond.

“Now 40 years old, the tunnel floor and rail track running through it is getting tired and it’s time to identify work needed to meet the forecasted increase in freight volumes along the busy East Coast Main Trunk (ECMT) in the coming years,” explains KiwiRail’s Northern Regional Manager Steve Collett.

“As freight wagons get heavier and rail increases in popularity so we need to ensure the infrastructure can cope, that is the tracks and tunnels can safely carry the bigger equipment and volumes,” says Steve.


“There are currently over 20 weekday freight train movements a day through the tunnel, with a similar number on the weekend and this is likely to increase.”

“Last month work we started on-going investigation work which will continue through until mid-late 2015.


The work involves the use of modern day technology such as ground penetrating radar (GPR) to scan the tunnel floor and assess its condition.


We’re also undertaking GPR checks for voids and cracking in the concrete floor slab, and monitoring water flows,” says Jeanine Benson, Project Director, Kaimai.


“All of this information will help us build up a picture of the work we have ahead of us over the coming years – the results will be used to develop a new track design that is appropriate for the increased weight of freight plus takes into account the geological conditions below.


Something which wasn’t possible at the time the tunnel was first built,” explains Jeanine.

“In addition to the track improvements we’ll be completely overhauling the communications system.


This will improve safety both for trains and people working in the tunnel. New power supplies will also be laid to each end of the tunnel to feed the new lighting and ventilation systems.

Last month crews worked intensively for 36 hours straight with four rotating nine-hour shifts in the Kaimai Tunnel, “We used a KiwiRail high-rail vehicles were used to transport the work crews into the tunnel – this was extremely useful as it is extremely long and time consuming,” says Jeanine. “Leading up to this the tunnel floor had been cleaned over a 17 week period.”

This work was performed off the back of the changeover of Bridge 48 on the ECMT which required the track to be closed to trains for a couple of days.


KiwiRail crews now work in the tunnel every Saturday to perform general maintenance tasks and collect readings from the monitoring systems installed earlier in the year continues.

A second two day intensive investigatory session is planned for early 2015.


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