Rimutaka road tunnels back on the agenda

By Don Farmer


Road tunnels for the Rimutaka Hill are back in the mix after completion of a study commissioned by Transit New Zealand.
Two tunnel options form part of the study carried out by consultants Duffill Watts and Tse, involving a short summit tunnel and a long tunnel passing beneath the Rimutakas.
In their report to Transit the consultants contend tunnels would be an excellent service linking Featherston with Upper Hutt but costs would rule them out as a viable, economic option.
The shorter summit tunnel would consist of 1.1km of new road either side of the summit and half a kilometre of actual tunnel whereas the long tunnel would mean constructing 3.1km of new road either side of the Rimutaka Hill, with a 3km tunnel carving its way under the hill.
On what is known as a rough order of costs the summit tunnel on today's prices would cost $157,330,000 and the longer tunnel a staggering $803,710,000.
Instead the consultants have recommended a series of realignment options for the hill road should be taken through to the next stage of assessment.
The consultant's report is expected to become a base document for discussion on hill road meetings involving the three Wairarapa mayors Garry Daniell, Gary McPhee and Adrienne Staples MP John Hayes, Greater Wellington Regional Council and the Automobile Association.
Mr Hayes said yesterday it had taken 2? years to get the study results, having been promised them every three months by Transit.
He described that as "appalling".
Duffill Watts and Tse were asked to carry out the study covering 28km of State Highway 2 between Featherston and Upper Hutt.
Its primary objective was to develop a preferred realignment over the hill with a minimum design speed of 55km/h with an implementation plan that would allow the State Highway Plan to be finished.
The new road would be of a minimum width of 7m with a 1.5m sealed shoulder on each side giving a minimum overall seal width of 10m with curve and sightline widening on corners.
The consultants believe having road alignments with a 55km/h design speed would bring better safety, a better level of service and travel times and better access that would benefit businesses, tourism, commuters and haulage companies.
In total, the study has identified 12 different realignment options ranging in cost from $1.2m to $11m with an average of $5.1m.
An economic analysis and a benefit-to-cost ratio has been calculated for each scheme.
Mr Hayes said he is seeking to find out what impact the building of the longer tunnel with a 90-100km/h design speed road would have on the Transmission Gully project.
He said building a road with a design speed of 55km/h is "third world standard" and is the type of thinking that meant the potential of the whole region, not just Wairarapa, would never been unleashed.
Mr Hayes said whereas he does not yet know if the tunnel options would be viable until he succeeds in getting further information from Transit, the longer tunnel option would cut three to 4km off the journey.

Although it seemed expensive it was actually cheaper than Transmission Gully and had a positive benefit to cost ratio, unlike the gully project.
Mr Hayes said any shortening of distance and the time it took for diesel engines to grind their way up the hill brought a huge benefit as far as the carbon footprint was concerned. He said the hill road should not be looked on as a Wairarapa problem. "This is a New Zealand infrastructural problem and must be expanded to involve the mayors from Wellington right through to Napier."

- WAIRARAPA TIMES-AGE

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