- Commonwealth Avenue Bridge, Canberra, ACT, Renewal project
National Capital Authority
2.1The National Capital Authority (NCA) seeks approval from the Committee to proceed with the proposed Commonwealth Avenue Bridge, Canberra, ACT, Renewal project.
2.2The project will strengthen and widen both bridge structures, upgrade the shared path approach ramps, replace the traffic and shared path safety barriers, and upgrade the lighting on the bridge.
2.3The NCA states that the ‘aim of the project is to ensure that the bridge can meet its current and future road user needs, provide better safety for users across the bridge and improve shared path amenity and connectivity’.
2.4The estimated cost of delivery of the project is $137.5 million (excluding GST).
2.5The project was referred to the Committee on 20 June 2023.
Conduct of the inquiry
2.6Following referral, the inquiry was publicised on the Committee’s website and via media release.
2.7The Committee received one submission and one confidential submission. A list of submissions is at Appendix A.
2.8On 21 August 2023, the Committee conducted a project briefing and public and in-camera hearing. A transcript of the public hearing is available on the Committee’s website.
Need for the works
2.9The Commonwealth Avenue Bridge forms part of the dual carriageway Commonwealth Avenue and comprises two separate parallel structures about 310 metres (m) in length. The bridge, as part of Commonwealth Avenue, provides a critical and strategically important arterial corridor in Canberra’s metropolitan transport network and is one of two major crossings over Lake Burley Griffin.
2.10The NCA have outlined three objectives that articulate the need and purpose for the works:
- Meeting current and future road user needs: the Commonwealth Bridge was designed in the late 1950s to a standard that accommodates a 32 tonne (T) HS20 vehicle. Commonwealth Avenue is classed as a ‘general access road,’ meaning vehicles with a load rating of up to 42.3T should be able to travel along this road.
- Improving shared user path needs: the shared paths on both sides of the Commonwealth Bridge that are used by cyclists and pedestrians are only 2.4m wide, which is not compliant with Austroads Guidelines or industry standards.
- Renewing active travel infrastructure: the existing traffic barriers and handrails on the Bridge do not comply with current standards. Existing pathways in the four approaches to the bridge and on the bridge provide low levels of accessibility compliance.
- The renewal will strengthen the bridge to a T44, which will accommodate the 42.5T requirement under the 1992 Austroads Bridge Design Code, double the width of the path system to 5m, significantly improving safety for both pedestrians and cyclists, and replace all barriers on both bridge spans to comply with code requirements and improve safety The Committee notes that the Commonwealth Avenue Bridge is not currently approved for heavy vehicle use, but that strengthening the Bridge will allow for an estimated 8,000 trips per hour across the Bridge by 2036
- The NCA advised the Committee that the renewal work was becoming urgent:
We've been getting reports on Commonwealth Avenue Bridge for a number of years which have told us how best to manage it into the future, and a few years ago we received a report that it was definitely time to start to look to strengthen the existing bridge to respond to changes to the number of people living in Canberra, the number of vehicles going across the bridge, the weight of those vehicles, and the pedestrians and cyclists using that bridge both to get to work and as a visitor attraction.
Options considered
2.13The NCA advised that they considered eight options before narrowing the selection to three:
- Option 1 (do nothing) was discounted as it does not result in the current bridge being strengthened or widened and therefore does not meet the objectives of the project, nor the current and anticipated needs of the community.
- Option 2 (strengthen and widen the existing bridge) was recommended as the preferred option as it increases the load baring capacity of the Bridge, upgrades vehicle and safety barriers and widens the pedestrian and cycle pathways, extending the design life of the Bridge by at least 50 years.
- Option 3 (replace the current bridge with a new twin bridge) which included the demolition of the current bridge and construction of a new twin bridge capable of carrying light rail, six lanes of vehicle traffic and bidirectional paths for cyclists and pedestrian but was discounted by the NCA due to the more immediate need to strengthen the Bridge to avoid failure of the existing structure.
- The NCA prefers Option 2, as it adequately meets the project objectives and user requirements, reduces the risk to the NCA and Australian Government and represents the greatest value for money outcome.
Scope of the works
2.15The scope of work for Option 2 is comprised of three elements:
- Element 1 – Bridge Strengthening: The Commonwealth Avenue Bridge will be strengthened by 54 per cent to enable T44/L44 traffic loading. This will be actioned through:
- Widening of all access holes inside the bridge.
- Web strengthening reinforcement at each bridge pier and span. This will include both vertical and horizontal dowel reinforcement.
- Bottom slab strengthening. This will involve longitudinal and dowel reinforcement between each pier.
- Top slab strengthening. This will involve longitudinal and dowel reinforcement at each pier.
- Thickened boxout to existing bridge tendons.
- Element 2 – Bridge Widening: Widening the Commonwealth Avenue Bridge is a critical element to the overall design and includes the following infrastructure:
- New internal steel trusses to support the new widened shared path and architectural cladding. The trusses will be at approximately 1.5m spacings longitudinal to the bridge.
- New bottom precast concrete slab/cladding. This will be supported off the bottom of the steel truss to match the current bridge profile.
- New pavement slab and precast edge beam.
- New concrete service tray to support existing utilities and services below the new pavement slab. Utility works for the project include all activities and works necessary for the disconnection adjustment and relocation of infrastructure related to utility services which are affected by the project.
- Element 3 – Active Travel Infrastructure: Active travel infrastructure will improve the safety and experience of all bridge users including connectivity by:
- Replacing all vehicle barriers on the bridge with a proprietary barrier such as the VGAN 300 TL4 barrier. The proposed barrier height is 1200mm with 1800mm post spacing. A rub rail will be attached to the back of the vehicle barrier. Consideration of lighting in the rub rail is being investigated.
- Replacing the shared path bridge balustrades. The proposed pedestrian balustrade height is 1200mm. A rub rail attached to the back of the vehicle barrier to avoid a cyclist from striking the barrier. Consideration of lighting in the rub rail is being investigated.
- Improvements to each bridge approach will provide better access for all users and integrate with the wider shared path network. Each approach will provide widened paths and new stairs, with the exception of the southwest approach which will only provide a new path. All works will be compliant with current accessibility standards.
- Removing the carpark at the bottom of the northeast ramp at Barrine Drive and replacing it with a new accessible pathway.
- Carrying out landscaping works as part of the Bridge’s approach which will be of low maintenance and low water use where applicable.
- In addition to the elements listed above, the project also includes the following general scope items:
- Bridge materials: the NCA will use light colours in the bridge and aluminium balustrades and crash barriers designs, precast panels in line with the existing panels and detail and textures and colours of the surrounding area and respond to them as part of the bridge materials. The materials will recognise the characteristic materials, textures and colours of the surrounding area and respond to them accordingly.
- Landscaping: new landscaping will be designed to improve path gradients and connections at all four abutments, and to be low maintenance and low water use.
- Planning and design concepts: the planning and design considerations for the bridge have included:
- meeting a design life of at least 50 years for the bridge
- complying with relevant government legislation
- compliance with Australian Standards and Austroads Guides relevant to bridge and road design
- meeting all relevant work health and safety standards
- the functional requirements of the project
- whole-of-life cycle cost and value for money requirements.
- Structural design: structural design of the Bridge will likely replicate existing structural systems and ensure that all works are designed to the current applicable design codes and be suited to long-term durability for exposure to traffic and pedestrian use in line with current and forecast use.
- Provisions for People with Disabilities: the project will comply with required provisions for disabled access detailed in the Disability Discrimination Act 1992, including addressing areas of previous non-compliance.
- Security Measures: the Design Consultant will consider design requirements to address security and crime prevention strategies for the project. Security requirements will be put in place to control unauthorised access, vandalism, or unintended damage to the project site.
- Fire protection: all construction and fire protection requirements will, as a minimum, be in accordance with applicable codes and standards.
- Occupational Health and Safety: a Safety in Design approach will address risk mitigations and document safety measures that will be adopted in both construction and operation of the works. The Construction Contractor will be required to develop and adhere to a safety management plan for the construction phase, which incorporates Safety in Design mitigations identified by the Design Consultant as well as other relevant risk mitigations, prior to commencing any works.
- Early engineering studies for strengthening the Commonwealth Avenue Bridge revealed it was not possible to strengthen the existing bridges to accommodate both traffic and a light rail system. At the moment, the most viable proposal for light rail is to construct a third bridge in the space between the northbound and southbound bridges, including ‘a safety walkway either side of where the rail carriages run.’
Potential impacts
2.18The Minister for the Environment included Lake Burley Griffin and adjacent lands on the Commonwealth Heritage List by gazette on 8 April 2022. The Bridge is within the boundary of the schedule of this gazette and is also immediately adjacent to the Parliament House vista, also included on the Commonwealth Heritage List.
2.19The NCA has conducted a heritage assessment for the project and concluded that the works will have minor to moderate impacts on several heritage values due to the substantial extension of the bridge, removal of parts of the original structure and necessary landscaping.
2.20The project is expected to impact the local community through construction works and disruptions to traffic flow (vehicular, cycle and pedestrian) leading to congestion and delays on Commonwealth Avenue and the surrounding road network. The NCA has developed a traffic management strategy to establish temporary traffic flow to segregate construction from road users and pedestrians, maintain current traffic movements and pedestrian access during works.
2.21The NCA considered the timing of the proposed works in relation to the construction of the light rail system and whether it would be preferable – from a buildability and congestion perspective – to do the works together. Although the timing of the light rail has not yet been finalised, it is likely to be beyond 2030. The engineering advice received by the NCA suggested that the strengthening work needed to be undertaken within a shorter timeframe to avoid reaching failure of the existing bridge.
2.22The NCA reported in its submission that there will be some noise impacts during construction, which will have a varying impact depending on the source of the noise and the proximity of the receiver. Noise levels will include demolition, removal of excavated material and internal works.
Community consultation
2.23The NCA reported in its submission to the Committee that it began its community consultation process in late 2020. The most recent community consultation was undertaken in April 2023, when the NCA published a public notice on the project webpage, held four community kiosk sessions and published an online survey for the public to provide feedback on the project. Community feedback issues include:
- road congestion, construction traffic and disruption during construction
- pedestrian and cyclist safety during construction
- the proposal to remove the carpark near the Lake Burley Griffin foreshore at Barrine Drive
- concern about the cost of the project
- the extent of the proposed upgrades to the path network surrounding the bridge
- how the project relates to light rail over Lake Burley Griffin.
Engagement with key stakeholders
2.24The NCA reported to the Committee that it has appeared before the Joint Standing Committee on the National Capital and External Territories for the Review of the National Capital Authority Annual Report 2021-22 Inquiry. In the 47th Parliament, the NCA has appeared twice on 8 December 2022 and 29 June 2023 and both hearings have discussed the progress of the Commonwealth Avenue Bridge Renewal project.
2.25The NCA noted during the public hearing that they had not formally briefed or contacted Local or Federal members of the Australian Capital Territory. The NCA stated that they had not received any requests from Members for briefings.
2.26The NCA stated to the Committee that they regularly meet with their counterparts in various ACT government directorates, and the Commonwealth Avenue Bridge strengthening project is a standing agenda item. More specifically, the NCA representatives in charge of the Commonwealth Avenue Bridge project meet at least monthly, and often fortnightly with the light rail system project team.
2.27The NCA reported to the Committee that they had engaged with a variety of internal and externals stakeholders during the project development phase including: the Lake User Group, Public Transport Canberra, local tourism experts and Pedal Power.
Cost of the works
2.28The estimated total capital delivery cost of the project is $137.5 million (excluding Goods and Services Tax). This includes all costs required for the delivery of the project including project management and design fees, construction costs, contingencies and escalation provisions.
2.29The NCA provided further details on project costs in its confidential submission and during an in-camera hearing.
Revenue
2.30There will be no revenue generated by this project.
Public value
2.31The NCA has assessed public value, opportunities and benefit to the community that would result from the proposed works:
- Employment opportunities – the project will generate short-term employment within the office fit-out and building infrastructure sectors and will provide local employment opportunities in a number of areas.
- Longevity – the renewal of the Bridge will ensure that it is able to meet the current and future standards for public consumption for at least 50 years.
- Increased access – the public will benefit from the renewal of the bridge with improved access over the Lake via widening of the shared user path which will adequately and safely cater to all users now and into the future, in accordance with current Austroads Standards. The bridge strengthening will enable the bridge to accommodate T44/L44 loads to match the load rating of the surrounding road network.
Committee comment
2.32The Committee is satisfied that the project has merit in terms of need, scope, and cost.
2.33The Committee recognises the need to strengthen the bridge to accommodate Canberra’s growing population and the increased use of electric vehicles in the Australian Capital Territory, however is concerned that the level of strengthening may not sufficiently future-proof the bridge. Firstly, the Committee notes that the Commonwealth Avenue Bridge will be strengthened to the 1992 Austroads Bridge Design Code and not an SM1600 load that can carry heavier vehicles.
2.34Secondly, the Committee notes the NCA’s decision to strengthen the existing bridge rather than demolish and replace it with a much more costly new structure that contains the proposed light rail system. The Committee acknowledges the level of uncertainty around extensions to the light rail, however remains concerned that the three-bridge proposal may prove impractical or impossible given the complexity of the design.
2.35For these reasons, it may be that the bridge will still require demolition and replacement in the future, rendering this expenditure redundant.
2.36The Committee therefore recommends that the NCA report back at six-monthly intervals on the progress of the project, including further developments of the light rail project that may have an impact on the long-term use of the bridge.
2.37The Committee was pleased to see that the NCA has developed a community consultation plan and requests the NCA reach out to all relevant Local and Federal Members of Parliament and Senators in the Australian Capital Territory to offer consultation on the project.
2.38Having regard to its role and responsibilities contained in the Public Works Committee Act 1969, the Committee is of the view that this project signifies value for money for the Commonwealth and constitutes a project which is fit-for-purpose, having regard to the established need.
2.39The Committee recommends that the National Capital Authority contact Local and Federal Members of Parliament of the Australian Capital Territory that may be affected by the proposed works to offer a project briefing and report on their progress to the Committee.
2.40The Committee recommends that the National Capital Authority report back to the Public Works Committee with six monthly written updates until the completion of the works.
2.41Updates to the Committee should include detail on the progress of bridge strengthening and widening works, and any changes to overall project design, scope and cost.
2.42The Committee recommends that the House of Representatives resolve, pursuant to section 18(7) of the Public Works Committee Act 1969, that it is expedient to carry out the following proposed works: National Capital Authority - Commonwealth Avenue Bridge Renewal project.
2.43Proponent entities must notify the Committee of any changes to the project, scope, time, cost, function, or design. The Committee also requires that a post-implementation report be provided within three months of project completion. A report template can be found on the Committee’s website.
Mr Graham Perrett MP
Chair