At 2582.6 m in length, Melbourne's West Gate Bridge is the second longest bridge in Australia. Completed in 1978 at a cost of $202 million, the bridge comprises a cable-stayed steel box girder, with two end concrete sections of similar design.

However, with Melbourne’s rapidly growing traffic demand, an increase in the capacity of the bridge was necessary. The winning proposal was to augment the number of traffic lanes by one each way, increasing the total from eight to ten. This additional loading required large areas of the concrete sections to be retrofitted with externally bonded, carbon fibre (CF) strengthening.

From the beginning, the Alliance design team worked closely with (BASF Construction Chemicals) the eventual supplier of the CF system adopted. This early planning, resulted in a number of world leading decisions, that ultimately allowed the construction team to deliver major savings to the project.

When works are completed in late 2010, it will stand as the largest CF strengthening project in the world (by a factor of four), with some staggering CF statistics, including over 100 km of equivalent "normal" laminate and 12,000 m2 of fabric.

Major issues discussed in this paper include:

• The Importance of early design development
• Ways to optimize carbon fibre design
• When to vary section size, E-modulus and tensile strength
• The cost and time advantages of “custom made” solutions
• How to cope with a demanding construction program
• Dealing with imperfect site conditions
• The value of Quality Assurance