The Birkenhead Bridge at Port Adelaide will be closed to cars for eight weeks for a $3.7m upgrade

If you regularly use the Birkenhead Bridge, you will need to find a new route for the next couple of months.

The Island Seaway steaming down the Port River through the Birkenhead Bridge, Port Adelaide, in 1988.

• Birkenhead Bridge upgrade will be in keeping with its heritage status
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A $3.7 million upgrade of the historic Birkenhead Bridge will start on Monday.

Motorists will be unable to use the state heritage-listed bridge for about eight weeks, while work to replace its timber roadway deck with fibre-reinforced polymer is undertaken.

The eastern timber footpath will be replaced with aluminium and there will be some minor steel protection works, resurfacing and line-marking.

Traffic will be diverted around the bridge via the Port River Expressway, Francis St, Perkins Drive and St Vincent St.

Detours will be in place for at least eight weeks while a $3.7 million upgrade of the Birkenhead Bridge is undertaken.

Pedestrians will be able to use the bridge, which opened in 1940, throughout the upgrade, however, there will be no access for marine users for about 10 weeks.

Most of the works, being carried out by SA company McMahon Services Australia, will take place Monday to Friday between 7am and 5pm, and on Saturdays between 7am and 3pm.

It is being done to ensure the bridge’s long-term structural integrity and safety for all users.

A heavy-vehicle weight limit, including buses, was placed on Birkenhead Bridge last year due to its age and deterioration.

Birkenhead Bridge was state heritage listed in 1993 because it was Australia’s first double bascule (opening) bridge.

The upgrade is expected to be completed late this year.