Structural damage has been found on Waitawheta Bridge No.1 in the Karangahake Gorge, prompting Hauraki District Council to temporarily reduce its maximum permitted vehicle load to 30 tonnes.
The special inspection took place in February, as part of Waka Kotahi NZ Transport Agency’s investigation into whether the bridge, which crosses the Ohinemuri River, could handle 50 tonne vehicles and therefore be a viable detour route for State Highway 2 through Waikino. The original weight restriction on the bridge was 44 tonnes.
However, during the last day of visual inspection and testing, spalled (breaking away) of concrete exposing reinforcement was identified in one of the central beams.
A safety-based approach was recommended by the report presented to councillors on March 11.
“It was noted that the beam [has] lost all or partially lost its post tensioning. Given that the bridge has been operating without any further distress… it is assumed that the bridge is able to operate by distributing the load well to the other non-defective beams,” the report said.
“However, due to the potential loss of the full beams post tensioning, it is recommended… [to] temporarily reduce the maximum permitted vehicle loading to a gross load of 30 tonnes.”
Signage will be installed in the coming weeks, and the council will notify trucking companies and affected users.
A further report is being prepared for the council’s May meeting to discuss options for the future of the bridge.
