Kwinana Freeway Interchanges & Extension - Tunnels

Project: Kwinana Freeway Interchanges & Extension -

Client: Main Roads WA
Contractor: Thiess Pty Ltd

The work extends over 25 km, with a structural component that includes six bridges on the existing Kwinana Freeway, two interchanges on the freeway extension, twin bridges taking the freeway over a local road, an adjacent grade separated crossing, three rail tunnels and seven underpasses. The project represents an extension to the Kwinana Freeway that significantly reduces travel time and congestion as well as improving safety and addressing environmental issues.


  • The bridge and tunnel works for the Kwinana Freeway Project set new standards in leading edge Design and Construct practices. The innovative solutions provided structural efficiency, cost effectiveness, ease of construction and a very high standard of quality and finish. Economies of time and scale were achieved, with results that exceeded expectations in both timing and budget.
  • A total of 12 bridges were designed, with varying requirements for width and span. There are a mix of single and two span structures. The freeway bridges have spans from 26 to 48m.
  • Wide, pretensioned, precast concrete trough beams (up to 200 tonnes in weight) and bifurcated columns, which have been developed in a modular format to accommodate different bridge widths and satisfy stringent, Road Authority aesthetic requirements. An innovative and economical abutment solution has been provided, with mechanically stabilised earth walls incorporating columns that are built into the foundations beneath the reinforced soil block.