Calls for a tunnel through the Manawatu Gorge probably don't stack up with some areas described as "dry Weet-Bix", Tararua District Council chief executive Blair King says.
There have been calls for the road through the Manawatu Gorge to be replaced because it's dangerous and closed too often by slips. In the past five years the road has been closed more than 30 times because of maintenance, slips, and crashes - nine times last year.
And while One News has reported alternative routes bring their own problems, Mr King told the Dannevirke News work on one route, the Saddle Rd, was making it a viable alternative to the Manawatu Gorge.
"The Saddle Rd is significantly better now for heavy truck traffic with a reduction in sharp corners allowing other traffic to pass safely, allowing trucks to have a smooth journey," he said.
"But the opportunities raised around a tunnel through the Manawatu Gorge don't stack up as a business case. Some of the material they would be boring through has been described as dry Weet-Bix. Even with anchors rock-drilled we have seen how quickly they fail."
Mr King, an engineer, said prospects for a road tunnel through the gorge don't look good when a proposal for a tunnel through the Rimutakas hasn't stacked up.
Meanwhile work on the Saddle Rd is making headway with several of the upgrade sites completed.
The project, which has involved road widening, better drainage , new kerbing, fencing and additional passing areas, began in early 2014.
Work on the road was seen as a priority after the Manawatu Gorge slip in 2011 which saw the highway closed for more than a year. This put an enormous strain on the Saddle Rd which was not designed to handle the heavy volume of traffic.
The project has been a collaboration of the New Zealand Transport Agency (NZTA), Tararua District Council, Manawatu District Council, Palmerston North City Council and the Tararua Alliance.
Ray Cannon, planning and asset manager at Tararua Alliance, said: "On top of these partners, we also have Stringfellows who have been the driver behind getting this work done and they have been outstanding."
Initially it was estimated the $4.5 million project would take two years. But an extra $3.8 million from NZTA enabled further work and pushed out the timeframe.
"The additional funding has meant we could do three more sites and we are now hoping we can complete the project by April 2017, with one more work season to go through," Mr Cannon said.
"The road is now probably 60 per cent better. I think the results and quality of work the NZTA see - because they drive over it quite often - has helped us justify the time increases and it hasn't been a problem. NZTA have been really supportive.
"For us, as a local authority managing a project of this nature, it demonstrates the ability of what we as local authorities can achieve when we work together."
Mr King said traffic is flowing over the Saddle Rd very well.
"Once winter is over we will knit the old and new seal on the road which will also make a difference."
Joshua Webster, design and engineering team leader for the Tararua Alliance, said people who haven't travelled the road for a while will be surprised.
"It's the wow factor. In the past people may not have had a pleasant experience driving the Saddle Rd, hopefully now they will go over it and see what's been done and say, 'wow where's this come from?'
"It's been a major job and a great experience and we are getting some great results."
Mr Cannon said there's been a very strong collaborative approach to the whole project, with no single party driving it.
"We've a group of three authorities working under one umbrella to try and enhance a road for the benefit of the region and that's what we are doing."