Extensive tunnelling work carried out on five tunnels on the main trunk line at Paekakariki has assisted Tranz Rail in
its moves to standardise rail freight traffic throughout the North Island and remove significant volumes of heavy trucks
from roads between Palmerston North and Wellington.
Tranz Rail carried out significant work in the tunnels over the weekends of March 2,3 and 9,10 to lower the current
line, raise tunnel roofs and realign tracks. The work removes a significant constraint from Tranz Rail's freight network
into and out of Wellington by allowing hi-cube containers through the tunnels.
Hi-cubes make up about 40% of all containerised freight but height restrictions in the tunnels meant Tranz Rail had to
tranship these containers via road from Palmerston North or use a limited number of specialist low-load wagons to move
this freight.
"We were previously limited by the number of specialist UKA wagons we had in service on this part of the network," says
Tranz Rail's General Manager Sales and Marketing Craig Stapleton. "But now we can use standard UK wagons to carry these
2.9 metre (9 foot 6 inch) containers and no longer need to move them via road between Palmerston North and Wellington.
"This is great news for our freight customers as the widely used hi-cubes can now be moved directly between Wellington
and points north on the one train without the need to trans-ship containers via road," says Mr Stapleton.
"That should immediately remove about 60 to 70 trucks per week from the road between Wellington and Palmerston North and
should also have a flow-on effect for freight customers further north who may now look more favourably on rail as a
direct option to and from Wellington.
Mr Stapleton said removing this bottleneck from the system would bring more consistency for on-time delivery.
"On time delivery, greater standardisation of our freight service and point-to-point, fixed consist trains are all part
of the ITP (Intermodal Transport Programme) we are currently introducing to our freight business.
"This is a significant step in achieving some of those goals on this part of the network. ITP is designed to make things
simpler and more efficient for our customers and removing this constraint certainly assists that process."
Mt Stapleton said Tranz Rail engineers had used a combination of a lowered floor and raised roof height to achieve the
necessary clearance following the use of ground penetrating radar to gather a detailed analysis of both the roof and
floor of the tunnels. A specially adapted digger was also used to carry out the grinding of the brick lining in the
tunnel roof.
He said track realignment that could lead to lifting of the speed restrictions in the area may also have a flow-on
benefit for Wellington commuter trains with the absence of restrictions assisting in maintaining the timetable.
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