A bridge used by commuters and visitors to Bristol's harbourside is set to be closed to cars, vans and lorries.

Within four years the Prince Street Bridge, which spans the docks near the Arnolfini arts centre, will have one lane used by the proposed bendy buses from Long Ashton park and ride into the city centre, while the other will be restricted to pedestrians and cyclists.

One lane was closed earlier this year, which led to an outcry and fears of traffic jams in nearby streets, particularly at peak times.

It will also mean motorists will have a lengthy detour to reach Prince Street or car parking in The Grove or Queen Square.

But Bristol's transport leader Jon Rogers said the volume of traffic using the Grade II-listed bridge was "not high" and he does not believe that full closure will lead to traffic chaos.

He said: "The levels of traffic using the bridge are not high and predictions of traffic chaos following a trial reduction in traffic did not turn out to be at all accurate.

"The chaos was in fact non-existent and I don't expect to hear that word connected with this bridge any more.

"Motorists are keen that we provide the kind of high-quality public transport that will tempt them out of their cars and well, this is it.

"It's time to bite the bullet. We're opening the bridge to a high-quality fast and efficient mode of public transport never seen before in Bristol.

"I am confident that many people who currently drive over the bridge will use it."

The bridge closure will be part of a Transport and Works Act Order to be submitted by Bristol and North Somerset councils early in the new year.

The order will provide the legal consent to build the £48 million first rapid transit route in Bristol, which is hoped to be up and running by 2013.

Transport experts looked at various ways to route the bendy buses over the docks, including building a new bridge.

They also considered widening and strengthening Prince Street Bridge.

The council spent £40,000 on alterations to the bridge to make it a one-lane system in January, with traffic lights controlling cars and cyclists.

The rapid transit is intended to provide an affordable, fast and reliable solution to Bristol's congestion.

Stops on the route would include Ashton Gate, the proposed site for Bristol City's stadium near Ashton Vale, Spike Island, the soon-to-be renovated Museum of Bristol, Cabot Circus, Broadmead and the Arnolfini.