One of Adelaide's busiest and most historic bridges may have to be replaced or closed.

Key points: The Adelaide Bridge connects the CBD and North Adelaide

The Adelaide Bridge connects the CBD and North Adelaide The Adelaide City Council has been told it might need to be replaced or closed

The Adelaide City Council has been told it might need to be replaced or closed Trucks over 26 tonnes will be banned from using the bridge

The Adelaide City Council has been told the condition of the King William Road bridge over the River Torrens connecting the CBD and North Adelaide was in "fair to average" condition.

It may need to be closed or replaced within 10 years, a council committee was told last night.

The eight-lane bridge — officially called the Adelaide Bridge — was built in 1931 and is on the South Australian Heritage Register.

Deputy Mayor Houssam Abiad said funding a replacement or fixing the existing bridge would be too expensive for the council to do on its own.

"The first thing we think of is safety for commuters in and out of the city and also how will the city be able to fund a new bridge or the improvement of a bridge?" he said.

"So there'll be a significant amount of talks with the Federal Government and the State Government over the next five to 15 years to make sure that that style of work is co-funded and supported by the State and Federal Government as well.

"It's a significant piece of infrastructure for our city and when those roads and bridges were built back in the past no-one could take into account the type of vehicles that would be used in the modern world."

Adelaide Oval with King William Road to the left. ( ABC News: Malcolm Sutton )

Trucks to be banned from bridge

Trucks weighing more than 26 tonnes will be banned from using the bridge.

Some trucks weighing up to 60 tonnes are expected to bring construction materials for an office building being built on Festival Plaza, between the Festival Centre and Parliament House.

They will have to come from the south, rather than over the bridge.

However, council staff told the meeting there were also concerns if trucks then started using the Victoria and Albert bridges more if the Adelaide Bridge was closed.

Mr Abiad said trucks such as garbage trucks and emergency service vehicles "will not be impacted as a result".

Concerns about future tram plans

Before last year's state election, the former Labor government promised to build a new tramline across the bridge connecting the CBD, North Adelaide and Prospect.

The Festival Plaza tram stop which opened on King William Road last year. ( ABC Radio Adelaide: Malcolm Sutton )

However, the new Liberal Government has focused on reviewing the whole public transport system rather than focusing on trams.

Mr Abiad said the tramline proposal had the council concerned.

"For us, it was always a concern for how the bridge could handle the weight of the tram, but we're also hearing with new technology and trackless trams that they weigh a lot less, so there's lots of factors to take into account," he said.

A new tramline spur ending at the Festival Centre on King William Road opened last year.

Trams used the bridge until the 1950s, however, they were much lighter than modern trams.

The Adelaide Bridge was last repaired 11 years ago.