​CODC draft bridge strategy gives clarity to critical to-do list

A draft bridge strategy developed by the Central Otago District Council’s roading team has identified priorities and provided insights into an estimated $20 million overhaul of the district’s ageing bridge network.

The Central Otago District Council (CODC) is required to submit its final roading work programme, and funding application for the next three years (2024-2027) to Waka Kotahi by 8 December 2023. The Council receives a 51% funding subsidy from the transport agency for bridge and structure component replacements.

At the Council meeting at Alexandra yesterday (Wednesday 30 August), the roading team presented a draft bridge strategy that highlighted the critical state of the district’s bridges and the prioritisation approach to be used in the funding application. This would help inform the Council’s Transportation Activity Management Plan, and ultimately the 2024 Long-term Plan.

CODC Infrastructure Manager Quinton Penniall said at least 30 of the district’s bridges were at the end or would be nearing the end on their useful lives within the next 10 years. The estimated cost to completely replace all bridges in the next decade would be about $20 million. Council’s current budget for all bridge maintenance and renewals is $660,000 per annum or $7.6 million over 10 years, and this replacement backlog will continue over the next 30 years as a ‘bow wave’ of bridge replacements approaches.

A specialist bridge engineer in collaboration with the Council has identified a backlog of work. An estimated $1.5m of maintenance and $2.5m of component replacement would be required to ensure existing assets reach the end of their useful lives.

The process to identify and prioritise known critical bridges has already commenced. Recommendations include Little Valley Bridge at Alexandra, which would involve replacement of the timber components ($2.3m bridge deck replacement) and strengthening of the piles, rather than replacement of the whole structure; Maniototo Road Bridge - earmarked for replacement and possible divestment. (Divestment is the Council potentially divesting itself of ownership of an asset.) Funding is also being sought for Scott Lane Bridge near Kyeburn, badly damaged by the 2021 January floods for replacement with lower-level service structure or alternatively no renewal may be considered. These recommendations are subject to Waka Kotahi approval for co-funding.

Decisions relating to the future of bridges may impact on levels of service and increase rates, and/or council debt, therefore would be a key consideration for Council’s Financial Strategy for the 2024 Long-term plan.

Crs Stu Duncan and Tracy Paterson, who lead the Council’s roading portfolio, commended the roading team on the “plan of attack” for the next 30 years.

“Great to having some forward movement, so thankyou to the team,” Cr Paterson said.

Today (31 August 2023) the roading team will be submitting its 3-year Land Transport Plan to Waka Kotahi.

This draft ‘best foot forward’ plan has been developed alongside the Long-Term Plan for Transportation. Essentially the plans are the same but work to slightly different time frames.

The Council approved recommendations for budget increases to maintain levels of service and address medium term bridge and pavement risks, along with draft maintenance and renewal budgets for submission to Waka Kotahi for the following years:

It has been identified that the Council has several strengths that put it in a good position to increase the chances of co-funding from Waka Kotahi.

Our Pavement and Surfacing Assets continued to perform well and achieve longer lives than expected and of most other roading authorities, in part because of the climate but also attributable to good maintenance practices, Mr Penniall said.

“Comparatively across New Zealand, we are one of the most cost-efficient networks. We are well regarded with Waka Kotahi and are often cited as an example of good and pragmatic stewards of a roading network.”

Council will have a further opportunity to refine this draft submission ahead of the final submission, which is due on 8 December 2023.