A routine inspection and assessment concluded the concrete pier crossheads supporting the bridge deck, were under pressure. Balvac worked collaboratively with National Highways to develop a propping solution to relieve both the dead and live loads on the bridge decks to help facilitate the repair and the strengthening of 15 pier crossheads.
The team successfully repaired seven crossheads using a combination of flowable, sprayed and hand-placed repair materials, as well as using a titanium mesh anode cathodic protection system. To protect the reinforced steel within non-accessible areas of the crossheads, we installed daisy chain anodes through 16m-long holes cored in centre of the crosshead to a +/- 50mm tolerance.
We worked collaboratively to develop suspended scaffold access which was part suspended from the deck structure and part supported through the crosshead pier. This innovative approach mitigated the need for cofferdams to be installed within the River Mersey, eliminating any associated risks, improving safety as well as providing a cost saving across the project.
Balvac worked closely with the principal designer to establish the condition of the remaining eight piers by undertaking trials to demonstrate the dimensional accuracy of concrete removal using hydro demolition. These trials provided confidence for the innovative unpropped solution to be implemented, providing time and cost savings.
The site is located east of the River Mersey and sits within an Environment Agency flood basin. To ensure minimal disruption, all temporary works including the site office and welfare facilities were designed to enable use of the basin during extreme weather conditions.
Balvac's project team, along with supply chain partners, helped to raise money for a local youth group to purchase crafting equipment and games for young people in Northenden.