The most disruptive stage of light rail 2A (Civic to Commonwealth Park) will begin next month, as the southbound bridge on Commonwealth Avenue is demolished to make way for the raising of London Circuit – but traffic flow will be maintained during peak hour, transport minister Chris Steel said today.

“A significant amount of construction work will be happening,” Mr Steel said. “The changed traffic conditions mean that it’s important that Canberra motorists remain alert to the changed conditions; that they follow signs; and that they look out for other motorists and pedestrians.”

Commonwealth Avenue will be closed between Parkes Way and Vernon Circle from 6pm on Sunday to 6am Monday. Detours will be in place via Parkes Way to access the city, while drivers travelling from south Canberra can use Kings Avenue Bridge.

From 20 August, northbound traffic heading towards Civic will be diverted onto a temporary new road on the west side of Commonwealth Avenue. Southbound traffic heading towards the lake will be diverted to the current northbound Commonwealth Avenue bridge over London Circuit.

The first bridge on the eastern side of Commonwealth Avenue over London Circuit will then be demolished; and that side of London Circuit will be raised to the same level as Commonwealth Avenue. New permanent southbound lanes will be built on the raised section, and another side track built on the eastern side.

Around the end of this year or early 2024, northbound traffic will be diverted onto the southbound lanes, and southbound traffic onto the new temporary road, so that the northbound bridge over London Circuit can be demolished on the western side.

“We’ve been working closely with the construction partners to make sure that as they undertake this major construction work that we minimise the disruption on traffic,” Mr Steel said.

“Originally, we had thought that there would be more disruption when the construction methodology was assumed to have one lane going northbound or southbound. We’ve actually been able to deliver two lanes of bi-directional traffic … at all times through the construction phase … which will minimise the disruption to traffic.”

The disruption has been factored into bus run times: delays are expected of up to eight minutes for southbound buses, and four minutes for northbound buses.

During the construction and demolition of bridge, temporary facilities for pedestrians and cyclists on the western side of Commonwealth Avenue will enable safe active travel: a shared path separated from the vehicle lanes by traffic barriers on the western side track, and a cyclist lane heading southbound next to the diverted southbound traffic lanes.

“We will have a fantastic project at the end, which will provide them with much better connections from the city to the lake,” Mr Steel said.

“We hope that this won’t be disruptive for motorists, but we are still asking them to rethink their routine during this period of major construction in the south part of the city. Think about using public transport; think about the other routes that are available on other roads like the Parkes Way / Kings Avenue Bridge to avoid the worst of the disruption.”

The Built for CBR website has information about travel impacts, alternative routes, and “tips that [Canberrans] need to make sure they can move efficiently during this period”, Mr Steel said.

More drivers are using major arterial roads like Parkes Way to avoid Commonwealth Avenue, the minister noted, while Canberrans are also using park-and-ride public transport and active travel.

Ashley Canif, project director for the light rail and raising London Circuit (Major Projects Canberra), said this stage was “where the significant construction comes in and the temporary traffic movements, before we move onto demolition of the bridges”.

“These are essential for us to then create that new at-level intersection, which is the crux of the raising London Circuit project. It provides a real enabling works for us then to move to stage 2A main works for light rail.”

Mr Steel hopes a period of El Niño dry weather will enable construction crews to complete this project next year.

Work will then start on extending light rail from Alinga Street to Commonwealth Park: putting in place light rail systems, stops, and laying track.

“We’ve already done a number of sub-projects within the light rail overall program, including the depot and light rail vehicle projects,” Mr Canif said.

The light rail depot at Mitchell will be expanded by mid-2024, while five new light rail vehicles will be delivered beginning next year, the government announced last year.