Dismantling the Sydney Harbour Bridge and floating in a new double-deck version built overseas sounds like a plan hatched over beers at the pub. But one man says it should be reality.

Former federal Liberal MP Ross Cameron approached the state government with the radical proposal, which he says would solve Sydney's worst transit ''choke point''.

Even better, it could be built using Chinese labour, at a fraction of the cost of the proposed $10 billion second harbour rail crossing, Mr Cameron says.

"If you left [the bridge] it would get increasingly dangerous and more bits of it will start falling off," he said, referring to an incident in March when loose metal plates caused commuter chaos.