Bridges

Cover of ABC2017-003-17
ABC2017-003-17
  • Publication no: ABC2017-003-17
  • Published: 20 April 2017

Munna Point Bridge was built in Noosa Heads, Queensland in the late 1970s. Over 1.8 million trips in each direction are made across the 106 metre bridge every year, by tourists and locals. The bridge is one of only two routes to reach the primary tourism attractions of Hastings Street, Main Beach, and Noosa National Park. Accordingly, it is a critical piece of infrastructure to facilitate Noosa’s economy as a lifestyle and tourism destination.

In the 1990’s, large cracks appeared in the precast concrete piles and cast-insitu pile caps. The cause was identified as chloride attack and alkali silica reaction (ASR). Later consultants concluded that the service life of the bridge would end in 2013, and drafted a $6 to 8 million plan to replace the full substructure.

In 2014, Noosa Shire Council and TOD Consulting’s engineers investigated the condition of the prestressed strands and steel reinforcement. They determined that remediation was viable. They jointly prepared a performance specification for a design and construct contract with the aim of extending the service life of the bridge by fifty years. The successful Contractor, Marine & Civil Maintenance, with its structural and durability consultants, achieved the project brief in 2015 for less than $3 million.

This paper describes the investigation and procurement process, including the assessment of the options available to the bridge owner and the subsequent design and construction of the works. The works included structural strengthening of the piles and pile caps and durability enhancement of the superstructure with specialist coatings and an impressed-current cathodic protection system. Impact on local users of the road and waterway was minimised.