The bridge was built in 1914 and has a vehicle weight limit of 6 tonnes. Photo / NZME
The bridge was built in 1914 and has a vehicle weight limit of 6 tonnes. Photo / NZME
A Whanganui community group says keeping the Dublin St Bridge could save millions and give the city another tourist attraction.
Replacing the bridge, built in 1914, is part of the Whanganui District Council’s long-term plan for 2024-2034, with a funding provision of $69 million.
It has a vehicle weight limitof 6 tonnes, meaning heavy vehicles cannot cross.
During hearings for the council’s 2025/26 annual plan, Dublin Bridge Group spokesman Brian Rhodes said a new river crossing could be built at Glasgow St.
It would “flow out” to all main highways and, if the Dublin St bridge remained in place, would not require cycleways and walkways.
Whanganui’s council is working on a detailed business case for a Dublin St replacement, to be presented to NZ Transport Agency Waka Kotahi for funding consideration.
Earlier this year, council civil engineer Thorbjoerg Saevarsdottir said the business case would look at “do we need a bridge, do we not need a bridge?, traffic modelling, etc”, and could take two years to complete.
Construction may not start for 10 years.
At the hearings, group member Dougal McIntosh read a letter from engineer Steve McClune which said the Dublin St Bridge was believed to be the first in New Zealand to use concrete casings sunk into a riverbed rather than piles.
“It was also the first road bridge in the country to be fitted with clip-on extensions to the sides,” he said.
“It is an indisputable icon of engineering in New Zealand.”
He said the bridge carried gas, sewerage and water lines over the river, and leaving it in place meant a reduced cost for the new one.
There would also be no demolition costs at Dublin St.
The group’s submission said its plan could save $50 million - $10m in demolition, $20m in service lines and $20m for a vehicles-only bridge.
Speaking to the Chronicle, Rhodes said those figures were estimates, reached after talking with consultants and engineers.
“Basically, we just want what’s best for Whanganui, including saving ratepayer money.
“There are options. We don’t want council going down the wrong track.”
The Mangaweka cantilever bridge (foreground) is now used by pedestrians and cyclists, with a bridge for vehicles opening in 2022.
Councillor Josh Chandulal-Mackay said he had been told Glasgow St was a liquefaction zone.
That is an area where some saturated soils, usually silts and sands, lose strength and stiffness and temporarily behave as a liquid in response to earthquake shaking.
According to the council’s district plan, there is a high-risk liquefaction zone running the length of Glasgow St, from Victoria Ave to Somme Pde.
“The present bridge casings are 9 metres below the river bed, it’s good stuff,” he said.
“You won’t be just floating on the top.”
Council transport manager Mark Allingham told the Chronicle that from aroading perspective, aliquefaction zone was “notaninsurmountable issue“,,but there could be additional costs.
“At the moment, we are only looking at funding and feasibility, not design,” he said.
“We are a long way from breaking ground or choosing an option of where we might put [the bridge].
“If the substructure of the [existing] bridge is really good, for example, that would lead to the conclusion that we would just need to put new decking on it.”
“Further down the track, we will go out to all of the community, and we may get other groups with other angles and good ideas.
“Again, we are just not at that point yet.”
Mike Tweed is a multimedia journalist at the Whanganui Chronicle. Since starting in March 2020, he has dabbled in everything from sport to music. At present his focus is local government, primarily the Whanganui District Council.