Ashburton District Councillors will vote this week on a recommendation to progress investment and detailed design for a second urban Ashburton bridge across the Ashburton River, off Chalmers Avenue and linking south via a new road to Grahams Road.

The recommendation is in a report accompanying the second stage of a business case for the second bridge, which says Chalmers Avenue was technically preferred over a duplicate State Highway 1 bridge off West Street.

The Chalmers Avenue bridge could be constructed largely off-line, would reduce traffic on the highway through Ashburton and make it safer for local road users, and support future growth at Lake Hood and Tinwald east, the business case said.

The duplicate SH1 bridge faced potentially significant property and constructability challenges and Waka Kotahi, a partner in bridge planning so far, says it would be very difficult to build on either side of the existing bridge.

At their meeting on Wednesday, Councillors will consider the recommendation to progress the business case to a more detailed and design phase and economic assessment of the Chalmers Avenue bridge option.

Ashburton District Mayor Neil Brown said the business case also recommended that Waka Kotahi extend the merge lanes at South Street/SH1 intersection next year and consider clip-on passing bays for cyclists on the existing bridge.

“It also suggests we explore on-demand public transport like Timaru’s and in the really long-term a walking/cycling bridge across the river from Tarbottons Road to the mountain bike park.

“If the recommendation succeeds, the detailed business case could be complete in 2024 and the project shovel ready for the next national Land Transport programme. Construction could begin by 2026.”

Transportation reports since 2006 have indicated the need for a second urban bridge and this year’s major flood in the Ashburton River, which led to the State Highway 1 bridge being damaged and temporarily closed, highlighted resilience issues for not only Ashburton, but the wider South Island.

A three-stage strategic business case was required to align with the 2018 Government Policy Statement, and began in September 2020. This required a fresh look at more options than before for active connectivity between Ashburton and Tinwald.

The business case work is being handled by consultants Stantec. Council secured $94,500 funding from the Provincial Growth Fund for the case and Waka Kotahi have also contributed $203,694; Council's own contribution was $101,206.

Mayor Brown said the drivers for the bridge were population growth and development in Ashburton and Tinwald, road safety, and inter-regional freight movement. There was also Government policy directives like encouraging more cycling and walking and dealing with climate change, which could bring more floods.

“It might seem a second bridge has been a long time in the planning, but without this detailed level of work so far, Council is highly unlikely to attract the 80 per cent funding from Government we budgeted for in our Long Term Plan.”

In its plan, Council estimated the cost of the bridge at $37 million, but that was before Covid-19 began affecting the construction industry and supply chains.

Council has tagged $500,000 to progress the business case to the final stage in 2021/22, which will involve design and geo-technical work at the Chalmers Avenue site. Another $7.5m has been budgeted in the Long Term Plan for Council’s anticipated share of the cost of construction.

Back in 2011, the Chalmers Avenue location was Council’s preferred location after evaluating eight options, and then secured land designation at a hearing in 2014.

“We know the community has debated the merits of different bridge options over the years and the writers of this second stage report say there is clear evidence that Chalmers Avenue is the strongest location, for a number of reasons.

“May’s floods showed how critical the existing State Highway 1 bridge is to not only Ashburton, but for transport links all around the South Island. Council has to get on with the job of improving that connectivity and the work done so far has been supported by Waka Kotahi.”