Mohaka River Bridge FRP

The effects of heavy transport on a critical bridge linking Hawke’s Bay with points north and south led to a significant FRP strengthening project for BBR Contech.

Built in 1962, the two-lane, steel-framed Mohaka River Bridge is located in an isolated area along the Napier-Taupo Road (State Highway 5). Elevated 50 metres above water level on two reinforced-concrete piers, it stretches 215 metres across the river – providing a vital thoroughfare for freight and passenger traffic throughout the year.

Having undergone seismic strengthening in 2009, the bridge’s concrete deck required, among other deck remediation works, FRP strengthening to cope with the increasingly heavy traffic load. Working for main contractor Fulton Hogan, BBR Contech was responsible for three key components of work on the underside of the deck: injecting flexible sealant into more than 1200 metres of cracks in the structure; applying 740 strips of 1.85-metre-long Sika CarboDur to the concrete surface; and finally applying a corrosion-inhibiting coating to give extra protection against the elements.

The seven-week project posed a number of challenges, not least the need for rigorous safety measures given the requirement to work on scaffolding high above the river. Time and traffic management was also a key component, as one lane of the bridge was closed and the speed limit reduced to 30 kilometres per hour. However, the result was well worth the wait, with a bridge designed to cope with traffic for many years to come.