Cover of New Mandurah Traffic Bridge: Incrementally Launched Superstructure with Curved Soffit
New Mandurah Traffic Bridge: Incrementally Launched Superstructure with Curved Soffit
  • Publication no: ABC2017-024-17
  • Published: 20 April 2017

The Old Mandurah Traffic Bridge carries Old Coast Road over Mandurah Estuary in the City of Mandurah, WA. The current structure is deteriorating and the existing two-lane road requires an upgrade to four lanes, due to increased population growth in the area.

A Community Reference Group established in 2012 developed a business case identifying redevelopment objectives important to the local community. Following this, the State Government awarded the design and construct project scheduled for completion in late 2017 to Georgiou Group Pty Ltd. The delivery is managed by Main Roads WA.

The new road alignment is a single curve throughout the bridge length in both plan and profile. This facilitates incremental launching of the superstructure, as well as providing an aesthetic sweeping curve visual impact and enabling construction across the Estuary to be substantially completed while the old bridge remains open for traffic, minimising disruptions. The bridge alignment is also dictated by severe constraints on the eastern foreshore due to the proximity of properties and heritage listed land.

The vertical profile provides the required vertical clearances for navigation, boardwalks and footpaths. Considering the importance of the site, the decision was made to adopt a unique curved soffit cross section constant along the full length of the bridge, resulting in a cost-effective landmark structure with a strong aesthetic appeal.

The new 243m long bridge has six spans, with 42 m long internal spans and 37.6 m long end spans. The post-tensioned superstructure is supported on visually simple but elegant columns constructed on piled foundations. Additional features include:

  • a 5 m wide lower level shared path that allows improved pedestrian experience
  • new fishing platforms
  • refurbished fishing platform constructed on a section of the existing bridge
  • durability considerations
  • enhanced lighting
  • public art and landscaping.