The main state highway south of Christchurch was closed after a crash Monday morning on the Rakaia bridge.

A truck and motorbike collided just before 10am. The motorcyclist was flown to Christchurch hospital but didn't survive his injuries.

This took the Labour Weekend's road toll to eight.

"That's really, really gutting to think that at the beginning of the weekend we had eight people that had a future - family, jobs, friends - and now they don't, and just so quickly as well," 

National Road Policing Director Superintendent Steve Greally told Newshub.

The eight fatalities occurred right across the country, including a devastating smash on Sunday near Whangarei.

"Going back a decade, this would be one of the worst Labour Day weekends we've experienced. I think we had seven last year, but we always say one death on our roads is one death too many," Supt Greally says.

There were two other serious incidents around Christchurch on Monday. Two were injured in a crash in the suburb of Templeton and a pedestrian was critically injured after being hit by a milk tanker on State Highway 1 near Kaiapoi.

Police say their messages are not getting through.

"We call it disappointing, we say we're frustrated," Supt Greally says.

"Most have heard us talk about this over the past several years, it's the same message that we're putting out. Terribly that message isn't getting through."

The road toll period doesn't end till 6am tomorrow.

"We don't want number nine," Supt Greally adds.

So police say be patient in long queues, don't speed and don't drive if impaired or fatigued.