Edinburgh West Liberal Democrat MSP Margaret Smith said the Forth Crossing Bill, which paves the way for the new 2 billion bridge, strips the city council of its powers to limit working hours and act over noise pollution.
She said: "Residents who are going to be affected by five or six years of construction will end up with less protection than people getting a block of flats at the bottom of their garden."
The code of construction practice drawn up for the project sets the normal working hours as 7am-7pm, Monday-Saturday, but allows Sunday and evening working if necessary.
Ms Smith has raised her concerns in an official objection to the Bill. She said: "I'm not suggesting they will be working 24/7 every single day for five years, but the protection against these things is being taken away."
She said there might well be occasions when the contractors could make a reasonable case for round-the-clock working.
But she said: "It's important to have an independent professional who will look at it and decide."
She said the Bill would leave it up to Transport Scotland and the contractors to decide.
Ms Smith said: "Our track record of dealing with Transport Scotland is such that I don't think people have a great deal of faith that if they don't have some kind of regulation they are going to do it out of the goodness of their heart."
Doug Tait, vice-chairman of BRIGS (Bridge Replacement Interests Group South), an umbrella group for local communities, said most of the residents' groups objecting to the Bill had also raised the issue of round-the-clock working.
He said: "Just imagine it, you've put up with the noise all day and you're trying to get your kids off to sleep."
City transport convener Gordon Mackenzie also voiced concern. He said: "We must safeguard the interests of residents during the construction period."
Sources at Transport Scotland said the proposed arrangements were due to the involvement of more than one council.
A Transport Scotland spokeswoman said the agency had carried out "significant and sustained consultation" with affected communities and their elected members.