Problem to be addressed
The Commonwealth Avenue Bridge (the Bridge) is one of two major bridges crossing Lake Burley Griffin and is a critical component of the transport network of Canberra and the Australian Capital Territory (ACT) overall. Located within Canberra’s Parliamentary Zone, the Bridge has considerable cultural and heritage value. The Bridge was built in the mid-1960s. Since its opening, patronage on the Bridge has grown substantially, and by 2017, peak period traffic levels were effectively at capacity. Current traffic on the Bridge makes it one of the busiest transport assets in Canberra.
The Bridge is ageing and has not undergone a significant upgrade since construction. The proposed project will include structural upgrades that are required to meet relevant design standards for load capacity, traffic lane width, safety barriers, and active transport corridor width. Upgrading the Bridge will also extend the design life by 50 years. Other benefits include travel time savings, vehicle operating cost savings, emissions savings and safety benefits for pedestrians, cyclists and vehicles. The Bridge forms part of the corridor for the planned extension of the Canberra Metro light rail network, which could include a separate structure between the spans.
Economic, social and environmental value
The proponent’s business case states that the net present value (NPV) of the preferred project option (Bridge upgrade) is $124.9 million with a benefit-cost ratio of 2.65, using a 7 per cent real discount rate and P80 capital cost estimates in 2019 prices*. Infrastructure Australia evaluated the business case and considers the project to have a strong strategic and economic case, but a reported economic, social and environmental value that is likely to be overstated.
*P80 costs used in accordance with guidance issued by the Parliamentary Standing Committee on Public Works (Commonwealth).