London Circuit will be closing from Friday night 8pm, as Stage 2 Light Rail works from the city to Woden commence.
London Circuit will close between Edinburgh Avenue and Constitution Avenue.
The two cloverleaf ramps from Commonwealth Avenue to Parkes Way and London Circuit will close permanently.
Recently installed traffic lights at the Coranderrk Street and Parkes Way roundabout are expected to start working in coming weeks, the ACT government said.
"Canberrans are encouraged to rethink their routine by riding, walking or scooting, using public transport or avoiding travel during peak periods where possible," the government said.
"Detours will be in place to maintain access to Constitution Avenue, City east and west and Parkes Way eastbound from Commonwealth Avenue during the works."
Drivers and other motorists coming from south Canberra will be most impacted by the construction.
The government said southsiders could access City west and east via Vernon Circle and Northbourne Avenue.
Those wanting to get to Parkes Way eastbound are advised to travel to Edinburgh Avenue via Vernon Circle.
Transport Minister Chris Steel said while there will be bus diversions, no stops will be missed.
"Once complete, the project will also create a safer environment for cyclists and pedestrians," he said.
