International engineering consultancy Arup has warned the Western Australian government that the Fremantle Traffic Bridge is still at significant risk of a vessel collision, which given its current state could result in a disastrous collapse.

In a report prepared in May for Western Australia’s Public Transport Authority and Main Roads, Arup said the frequent impacts suffered by the bridge over the past four decades have inflicted considerable damage, and that the structure remained “at continued risk of a more sufficient impact.”

The Fremantle Traffic Bridge is situated on Queen Victoria Street and serves as the primary crossing point over the Swan River. The road frequently experiences heavy traffic due to its role as the main road entering the city centre of Fremantle from the direction of Perth, as well as its close proximity to Fremantle Harbour.

The bridge is the fourth to have been built at the site since the 1860s, and has been in operation since the late 1930s despite designers only intending for it to remain in service for several years. Major strengthening and repair work was performed on the predominately timber structure in 1978 and 1982.

The warning from Arup follows a similar dour assessment released a decade ago which said the bridge was on the verge of reaching the end of its serviceable life.

That engineering report, which was commissioned by Main Roads and dates from 2004, concluded that the probability of a fatal collapse in the case of a ship collision was unacceptably high, at around 66 times above acceptable levels. According to the report, the risk created by failing to replace or upgrade the bridge was “intolerable.”

The latest report by Arup, working under the assumption that a replacement bridge will be built within the next one to two decades, recommended the construction of “glancing protection frames” to safeguard the septuagenerian structure from any unexpected impacts.

Main Roads said it would build a reinforced steel fender system next year in order to “mitigate impacts of glancing blows from large marine craft and to give added protection in the event of a head-on impact,” as well as install in-river navigational aids.

The measures are too few and too late for Fremantle MP Simone McGurk, who said the Barnett government had failed to properly address the potentially disastrous hazards surrounding the existing bridge.

“Labor allocated $80 million towards a new bridge but the Liberal Government stripped that allocation and has since done a series of expensive patch-up jobs,” McGurk said. “It’s an outrageously haphazard approach to a major piece of traffic infrastructure.”