Canterbury flooding: Ashburton Bridge temporarily reopens to light traffic

It could be another day before truck drivers know when they will be able to cross the flood-ravaged Ashburton Bridge, which is now open again to light vehicles for a few hours.

The bridge, on State Highway 1, crosses the Ashburton River and is the primary transport route for southbound travellers. It closed on Tuesday morning after days of wild weather in the Canterbury region.

It reopened overnight to light vehicles but closed again for more load testing at about 10am on Wednesday.

Now the bridge is open again - but only temporarily. It reopened at 2:30pm and will close between 6pm and 8pm for further investigations.

Speaking to Newshub on Wednesday afternoon, NZ Transport Agency maintenance contract manager John Keenan said engineers were currently underneath the bridge inspecting the structure.

"What we're trying to ascertain, at the present point in time is; 'is the bridge safe for heavy vehicles or not?'"

Keenan said a timeline on when trucks will be able to get over the bridge isn't yet clear.

"[It could] potentially be late today - 24 hours' time we'll have a good idea of what can and can't happen.

"Things may remain the same as they were last night into the next 24 hour period."

An Ashburton bypass opened on Tuesday night after the wild weather also knocked out alternative routes. That's meant a backlog of trucks has been able to get moving again - albeit at a slow pace. 

Some queues are at a standstill and others travelling at a snail pace along the inland bypass.

"I've been sitting in this line for about an hour so far and we've moved about 500m," one truck driver told Newshub.

"It's not the first queue today," another said. "[It's] frustrating but there's not much we can do about it really."

Road Transport Forum chief executive Nick Leggett is urging truckies to stay safe on the alternative routes.