A £500million town centre regeneration scheme could see the Queensway underpass scrapped and used as a giant underground flood water tank, it has been revealed.

Plans to ditch the busy dual carriageway underpass have caused outrage among councillors who say they were kept in the dark about the planned changes.

A consultation launched this week revealed plans to remove the dual carriageway underpass which allows traffic to flow to the seafront without using the Porters roundabout. The void will be used to site a tank which will help prevent the seafront flooding during heavy downpours.

The plan, being delivered in partnership with Swan Housing, will see all traffic to and from Victoria Gateway negotiating two light controlled pedestrian crossings and merging on to the Porters Grange roundabout.

The scheme includes 1,650 new homes along the Queensway. Former council leader Tony Cox said: “You might as well put a sign up at Progress Road saying ‘Southend is closed for business’. They want the underpass to be an underground water fill storage tank? This was a complete ambush. It has been railroaded through.

“Even on non-sunny days Queensway often grinds to a halt, but with two pedestrian crossings it will be impossible.”

Kevin Buck, shadow councillor responsible for transport, said: “We welcome the homes, but this doesn’t serve our demographic well. Four lanes of traffic dissect the development.

“It is a major through-road through the centre of Queensway. This doesn’t help the motorist trying to get through Queensway at all and will only create congestion.”

Mr Buck added: “The development is fine but this scheme will have to last up to the next 100 years. We’ve got to get it right now.

“Officers said having an underpass is not financially viable but we already have an underpass. They plan to put an attenuation tank in the underpass to take away seafront flood water. There would be all the huge cost of laying pipework.

“Why didn’t they make it part of the Seaway scheme?”

Martin Terry, councillor responsible for community safety and customer contact, added: “Myself and the majority of the cabinet share deep concerns about these proposals which are a dramatic change from what was previously discussed.

“This is a major road and we can’t afford to jam up that area. We all know when London comes to Southend in the summer we already struggle.”