Commonwealth Avenue Bridge Renewal Project

Due to its remarkable engineering design, Commonwealth Avenue Bridge has not undergone any significant upgrades for sixty years. In this time we have seen the size and weight of everyday vehicles increase. It is important to ensure the bridge is upgraded to accommodate these increasing vehicle sizes today and into the future.

Whilst these strengthening works will increase the bridge’s load rating to accommodate heavier vehicles up to 44 tonnes, vehicle limits across the bridge will remain consistent with the authorised heavy vehicle routes determined by the National Heavy Vehicle Regulator.

In addition to the traffic lanes, Commonwealth Avenue Bridge is the primary north-south link for pedestrians and active travel users. At only 2.4 metres wide, the existing shared paths on both sides of the bridge do not meet Austroad Guidelines or industry standards. The project will double the width of the path system, significantly improving safety for both pedestrians and cyclists.

On 8 April 2022, the Minister for the Environment included Lake Burley Griffin and Adjacent Lands in the Commonwealth Heritage List. Commonwealth Avenue Bridge is not itself heritage listed, but it is included within the boundary of the Lake Burley Griffin listed area and contributes to its heritage values.  

A heritage impact assessment has been prepared as part of the design for the works.

The report identified the proposed works would have a moderate impact on several heritage values because of the bridge widening which would remove parts of the original structure and handrails, impacting several creative qualities. However, the design of the extensions to the bridge has sought to minimise the impact through the simple, modern form and materials selected.

There was also a minor impact noted because of the bridge’s changed appearance, including to the landscaping. These impacts would be greater at close range, but less perceptible from further away. New plantings are expected to mitigate this landscape impact over time.

Otherwise, no additional heritage values were noted.

The project will have regard for preserving the historical significance of the bridge. 

The upgraded bridge will generally retain its current visual appearance. New materials being used to upgrade the bridge will not be visible due to their location within the bridge and those used for the widening of the bridge will complement the existing look of the bridge.

Both sets of flagpoles have been removed to allow construction activities associated with the project to take place. There are no current plans to reinstate the flagpoles following construction. The flagpoles along Kings Avenue will remain.

There will be significant closures and traffic impacts during construction and Canberrans are urged to plan ahead and, if possible, consider changes to how you travel. 

To ensure one side of the bridge remains open, works will be undertaken on the northbound side of the bridge first, before progressing to the southbound side. 

During construction there will be two northbound lanes and one southbound lane available on the open bridge side. There will be one lane of general vehicle traffic in both directions. The second northbound lane will be a bus and emergency services priority lane.

The road network will be monitored and we will work closely with the ACT Government to communicate about impacts and alternate routes. We recognise this is going to be disruptive for the community and visitors to the National Capital and are committed to completing works as efficiently and safely as possible. 

The water level of Lake Burley Griffin is lowered to manage risks associated with construction activities on the Scrivener Dam Dissipator Strengthening Project. The lake is lowered to a maximum of 500mm below normal levels for the duration of construction.

On the Commonwealth Avenue Bridge Renewal Project, the majority of works will occur either inside the bridge deck or beneath the bridge and may not be highly visible to the public. Works beneath the bridge will be carried out from barges and these will arrive in January 2026. There will be some impacts for lake users, including gradual closures of sections of the lake beneath the bridge as works progress.

We urge all lake users to consider the impacts and potential new hazards prior to setting out onto the water.

There will be changes for public transport users. Updated timetables and school packs can be viewed and downloaded on Transport Canberra's website here: Transport.act.gov.au/updated-timetable.

The NCA has and will continue to work closely with the ACT Government to minimise impacts for all road users as much as possible during the construction period. A dedicated northbound bus priority lane has been provided.

Due to the nature of the works being undertaken to strengthen the bridge, it is necessary to close the bridge. These works include replacement of the bridge bearings which sit between the bridge deck and the bridge piers. The bridge will be lifted off the existing piers to complete this work and it is critical there is no additional load on the bridge during this time. 

Furthermore, as part of the works holes will be cut in the bridge deck to allow access for pouring the reinforced concrete slabs inside the bridge. Both these activities necessitate the closure of the affected bridge side to ensure the safety of both the workers and the public. 

Both the NCA and our contractors are subject to the highest standards of work, health and safety and these guide us in developing our construction programs. It is important to acknowledge we are working in a very constrained environment both in terms of confined spaces within the bridge and the added challenge of working over water. 

The NCA considered the options of extended hours of work, however this would significantly increase cost of the project and increase on-site risks during construction. All these factors were considered and balanced appropriately. We are committed to completing works as efficiently and safely as possible and will seek to identify opportunities to accelerate works where possible.

The Commonwealth Avenue Bridge Renewal Project is unrelated to the ACT Government's plan to extend the Light Rail from Civic to Woden.  

To learn more about the light rail project, please visit the ACT Government's website.

The NCA is working closely with the ACT Government to coordinate construction programs, disruption and communication activities wherever possible.

The area of Commonwealth Avenue Bridge is a constrained environment. To complete these necessary upgrades, our project team needs to work above, below and between the two bridge spans. To construct these works at the same time as the proposed works being delivered with Light Rail Stage 2B would further constrain the environment, making it unsafe for two project teams and all the necessary machinery and activities to co-exist.

The NCA will continue to work with stakeholders, including the ACT Government, to manage the impact of this project and its interrelationship with other works in and around the vicinity.  

The NCA will continue to keep community members and other stakeholders updated on project status and arrangements for traffic management throughout construction. 

You can stay informed by subscribing to our mailing list using the link above, or by following the project updates on our website or social media. If you have any questions about the project you can email us at communications@nca.gov.au