The ramp is expected to be closed from April 19, 9.30am until Monday, April 22, 6am.

A detour will be in place.

Drivers will have to continue along Parkes Way towards Campbell before turning around at the Coranderrk Street roundabout.

They will then take the third exit, head back towards Acton and turn onto Commonwealth Avenue.

The temporary closure is to allow for pavements, drainage, kerbs and streetlights to be installed.

"Work will be undertaken throughout the whole week, including nights and the weekend," the government website says.

The ACT government expects the light rail to Woden to be built between 2028 and 2023.

The Canberra Liberals have claimed the extension will cost $1.46 billion.

Chief Minister Andrew Barr said the cost included delivery of the existing network, which runs from Gunghalin to the city.