Repairs to the slump in the Ashburton River bridge have been completed, ending many months of roading works and delays following damage caused by flooding in late-May.
During the floods tree logs dammed the northern end of the State Highway One bridge which funnelled a high volume of water towards a bridge pier.
It scoured the bottom of the pier which lost some of its support and settled, causing the bridge to slump.
New Zealand Transport Agency (NZTA) Central South Island system manager Mark Pinner said the first point of repair was to make sure the bridge was okay.
“We put heavy lorries on to make sure it didn’t flex too much,” he said.
Contractors jacked up the bridge to get it level and then re-built the pier support with reinforced concrete to provide a robust connection between it and the beams.
Bridge resurfacing was the last work carried out last weekend.
The cost of the repair work has come in at around $500,000 and has involved around half a dozen workers at a time, with more contractors working in other areas around the bridge.
“We’re prepared for this kind of event but you never know how it will unfold,” Mr Pinner said.
“The biggest impact is on the travellers, and we try to minimise that delay.”
NZTA have installed a sensor on the recently repaired Ashburton River bridge so they can remotely monitor any movement for at least the next 12 months.
Contractors got access to the bridge once the main river flow was diverted away from the damaged pier.
Mr Pinner said the agency would work with Environment Canterbury to manage the river and restore the waterway to its best capacity “and look at the driftwood that came down and work with them to see where that goes.”
He was pleased with how smoothly the work had gone, causing as little disruption to traffic as possible.
“We’ve got a great team behind us, we were able to get into it really quickly and we did manage to keep the road open the majority of the time.”
By Daniel Tobin