Traffic is expected to be diverted onto a temporary road from mid next month to allow for the demolition of a bridge over London Circuit.
The bridges, which carry Commonwealth Avenue across London Circuit, are to be demolished as part of works to prepare for the extension of light rail.
A temporary road on the west side of Commonwealth Avenue will mean the road carries two lanes of traffic in both directions during peak hours, the government said.
Motorists travelling north on Commonwealth Avenue towards the city would be diverted onto the temporary road from mid-August, the government expects.
Southbound motorists would be diverted onto the current northbound bridge which spans London Circuit.
Transport Minister Chris Steel said the temporary roads would allow work to proceed while disruptions were minimised for motorists.
"This is a significant milestone for the project as we start to see London Circuit being raised by six metres to be level with Commonwealth Avenue, which is essential to bring light rail to Commonwealth Park and then down to Woden," Mr Steel said.
A full closure of Commonwealth Avenue between Vernon Circle and Parkes Way would be required before traffic can be diverted.
The road will be closed from 6pm Sunday to 6am Monday on the day before the temporary road opens to traffic.
Mr Steel said there would be a separated shared path on the western temporary road as well as a cycle lane heading southbound.
"We said this project will be particularly disruptive this year and with this significant traffic change we urge all road users to be alert, slow down, follow traffic signs in the area, allow additional travel time and plan their journey," he said in a statement.
Once the southbound bridge over London Circuit is demolished, fill will be used to build up the eastern side of London Circuit.
Permanent southbound lanes will be built on the raised section while another side track temporary road will be built to allow the northbound bridge to be removed.
Meanwhile, plans for the relocation of utilities along Commonwealth Avenue to enable light rail were on Tuesday released by the federal government for public comment under the provisions of the Environment Protection and Biodiversity Conservation Act.
Works would include the relocation of fibre optic communication cables so they can be accessed without interfering with future light rail services.
"Fibre optic cables that would intercept with the alignment for this part of the network would be relocated between Albert Street, underneath Lake Burley Griffin towards the southwestern cloverleaf where Flynn Drive and Commonwealth Avenue intersect, towards the on-ramp off Flynn Drive, continuing along King Edwards Terrace onto Mall Road West, where the alignment ends," a project description said.
A spokesman for the ACT government said the works were required to avoid intercepts with the construction area of the light rail project along Commonwealth Avenue.
"The relocated assets must connect into the existing telecommunication networks which determines the connection points," the spokesman said.
"The utility authorities have indicated that the required connection point to their existing assets is on King Edward Terrace (in proximity to Mall Road West)."
The ACT government has not ruled out building light rail along King Edward Terrace on its route to Woden, but the preferred route remains a more direct path along State Circle.
We've made it a whole lot easier for you to have your say. Our new comment platform requires only one log-in to access articles and to join the discussion on The Canberra Times website. Find out how to register so you can enjoy civil, friendly and engaging discussions. See our moderation policy here.
