New flood warning signs on Anzac Drive have already been flipped into action, just days after they were installed.

The permanent signs have been placed along State Highway 74 between Pages Road and Breezes Road, allowing contractors to quickly warn motorists when surface flooding develops.

The signs normally remain folded closed but can be opened within moments when heavy rain causes water to collect across the road.

NZ Transport Agency regional relationships director James Caygill said the system would avoid delays caused by transporting temporary signs to the area during storms.

Contractors are often responding to problems across the city when heavy rain hits.

“Driving through even shallow water can pull on steering and reduce traction, so being aware and slowing down is important,” Caygill said.

“There is always a risk of something under the water that is not visible, such as debris or potholes.”

The flood prone section of Anzac Drive is close to the Bexley red zone, where land subsidence has changed natural drainage paths.

Water can remain on the road for longer before draining away, creating a hazard during periods of heavy rain.

Caygill said the new signs would not solve the underlying problems but would give drivers faster warning.

“It is an important measure to help keep people safe, along with ongoing maintenance to keep drains clear and functioning, until a larger project addresses the wider catchment and land issues causing the flooding,” he said.

The planned replacement of the Pages Road Bridge will include changes to the bridge approaches and additional local drainage.

The Christchurch City Council project, which is receiving funding from the Transport Agency, is expected to improve drainage across the wider catchment and provide some relief for Anzac Drive.