NZTA has released plans for a temporary roundabout at a busy intersection near Christchurch Airport.

SUPPLIED The planned $90 million Memorial Gateway at the intersection of Russley Rd and Memorial Ave.

The NZ Transport Agency (NZTA) has released plans for a temporary roundabout at a busy intersection near Christchurch Airport.

The new layout at the intersection of Russley Rd and Memorial Ave would open to the public by March 20.

It would remain in place until construction of the Russley Rd overbridge was finished, which NZTA said would be in two years.

NZTA highways manager Colin Knaggs said the "much larger and longer roundabout" would combine give way road markings and traffic signals.

"The traffic signals will stop traffic coming from Russley Rd so drivers from Memorial Ave will be able to enter the roundabout."

Knaggs said drivers needed to be careful when entering the roundabout, which would be three lanes wide in some places.

Earlier developments in NZTA's Christchurch motorways project were criticised by police as exposing motorists to a "potential crash risk".

"It will look quite different with the roundabout stretching 500 metres along Russley Rd, but ultimately it is a roundabout and the normal road rules apply," Knaggs said.

NZTA said the choice to construct the roundabout was made to "reduce the number of temporary traffic changes" during construction of the overbridge.

The roundabout was the latest development in the Government's roads of national significance programme, made up of seven major roading projects across New Zealand.