Tomarata Bridge

24 April 2019

In December 2018, Council had to temporarily close the Tomarata Road Bridge that is on the main route to Mangawhai Village. The decision to close the bridge was not made lightly, and the mitigation of further damages to the bridge combined with the need for a safe route that motorists could use at all times were the priorities for Council. Further investigations were needed to come up with temporary and long term solutions, but with it being so close to Christmas and the engineering industry shutdown for the holidays it was not possible to provide a safe alternative solution prior to Christmas so the bridge was temporarily closed.

Following the additional detailed assessments it was determined significant remediation works would be required to strengthen the bridge and enable it to be fully opened to all traffic. The weakened structure had reduced the bridges ability to carry full traffic loading and is the sole reason the solution of temporarily restricting it to one way traffic was employed. In the short term by installing temporary traffic lights to control the flow of traffic over the bridge and, keeping the traffic centred over the main structure Council is able to maintain two way traffic past the bridge without restricting trucks from using it until repairs can be completed.

The repairs needed are to remedy the damages caused by salt water. As the bridge crosses the Mangawhai estuary it is constantly exposed to a marine environment, which over time has caused severe corrosion and concrete spalling to the bridges bearers and beams. To repair the bridge involves specialist removal of any damaged concrete to expose the corroded steel reinforcing, replacing the compromised steel and then repairing any damaged concrete. Additionally sacrificial anodes will be installed to stop any further corrosion of the steel once the repairs are completed.

A contract for the repairs was drawn up and went to market in February 2019. Tenders for the contract closed on the 18th March 2019, from which Council received two submissions. Councils engineering staff evaluated both of the submissions and it was deemed that both were non-conforming tenders.

Because of the lack of acceptable tender submissions Council now have to re-tender the contract. As part of the review process before re-tendering can happen, Council’s engineers have contacted the wider structural engineering and contracting industry to discuss the lack of submissions for this project. Advice back from the industry was that, the timeframes for delivery of this work combined with pressures from other projects already being constructed have created a significant risk and deliverables for all existing and new work would be unachievable. Council engineers have taken this feedback on board and with some minor changes to the tender around timeframes and deliverables are confident that additional contractors will now make submissions to the tender.

Going forward there is a procurement process that needs to happen to ensure an open, transparent process has been followed. As a result of the processes to award such a significant piece of work, the revised timetable and the complex nature of the project, it could mean that construction may end up running through to December 2019.

Obviously, this is not an ideal situation and poses some inconvenience to the regular users of Tomarata Road and those travelling into Mangawhai, however safety of all road users must take precedent and the single lane/traffic light system is the safest way the bridge can operate in its current state without closing it completely.

Council will continue to keep the residents of Mangawhai updated around the tendering process progress and expected work dates.