Problem to be addressed
The Princes Highway is the main north–south link between Sydney and southern New South Wales via the Illawarra and Shoalhaven regions. It is the main connecting route for coastal communities and carries a mix of freight and passenger traffic for local, long-distance and tourism trips. At Nowra, the Princes Highway crosses the Shoalhaven River via the Nowra Bridge, which comprises a steel bridge built in 1881 for southbound traffic, and a concrete bridge built in 1981 for northbound traffic. There are no other crossings of the river on the coastal plain.
Over 51,000 vehicles use the crossing every day and this is forecast to grow by 1.4% per year between 2026 and 2036. Heavy congestion is experienced on the Nowra Bridge and nearby Princes Highway intersections during the morning and afternoon peak periods. Crash rates along this route are also worse than the NSW average for the same class of road. Recognising the costs of these problems, the Infrastructure Priority List includes the Shoalhaven River Crossing Capacity as a near‑term Priority Initiative.
The Nowra Bridge Project involves the construction of a new four-lane bridge immediately to the west (upstream) of the existing bridges, which would become the new crossing for northbound traffic. The existing northbound bridge would be converted for southbound traffic, allowing the much older southbound bridge to be re-purposed for community uses. The project has strategic merit as it supports local, regional and tourist traffic, and allows for more efficient movement of freight on this important highway.
Economic, social and environmental value
The proponent’s reported net present value (NPV) for the project is $268 million, with a benefit-cost ratio (BCR) of 2.2 using a 7% real discount rate and P50 cost estimate. Infrastructure Australia has independently reviewed the business case and agrees with the proponent that the project’s benefits would outweigh its costs. To inform project delivery, the proponent undertook an industry standard procurement assessment which recommended a single Design and Construct contract package. The risk identification, assessment and mitigation approach developed in the business case appears appropriate, although risk management will continue through the design and construction process.