Bridges

The Maribyrnong River Bridges (also known as E.J. Whitten Bridge), is Victoria’s second largest road bridge being a 520 m long ten span structure that carries the M80 Ring Road over the Maribyrnong River in the outer western suburbs of Melbourne. The original structure was built in the early 1990s and consists of two parallel concrete box girders with typical spans of 54 m.

The strengthening and widening works are being undertaken by a Design Joint Venture between Arup, Flint & Neill and SMEC, and constructed by Fulton Hogan, as part of the M80 Ring Road Upgrade Project – Sunshine Avenue to Calder Freeway. The aim of the project is to provide an additional 2 lanes of traffic in each direction by infilling the gap between the two existing concrete box girders with new superstructure consisting of twin steel box girders with a composite concrete deck.

This paper will discuss the proposed strengthening and widening solutions adopted in the design and the integrated construction methodology. In particular, challenges that have arisen through the design process include;

• Shortcomings in the existing structure which was designed to the 1992 Austroads Bridge Design Code, when carrying out an assessment using the current version of AS5100, including the adopting of mixed vehicle loading on the structure and the increase in barrier performance level.
• Suitability of the intended widening construction methodology that was devised at the time of the original construction, and the resulting structural form, construction sequence and methodology.
• Sensitivity of the widened structures and insitu stitch to variation in stiffness between thes new and existing structures.