Kenilworth residents are warning of traffic "chaos" for eight years after proposed construction details were revealed for the HS2 rail line.
Infrastructure plans for creating the route between London and the West Midlands were announced on Tuesday.
They include a new village for workers at Stoneleigh, a power station between Coventry and Kenilworth and a contra-flow system on the A46.
Joe Elliot, local resident, said: "It's going to be a nightmare."
Mr Elliot, a member of campaign group Stop HS2, added: "If you look at the chaos caused through one lane being shut the other morning, this is going to be a contra-flow system on the A46... for between five and eight years.
"How are people going to get from Coventry to Warwickshire and vice versa down the A46? All the roads through Kenilworth, through Stoneleigh are going to be either closed or severely disrupted for years."
A larger area is now expected to be disrupted by the work for the route to negotiate Canley Brook.
An HS2 spokesman said: "Our current plan is to move the alignment of the brook so our trains can pass through without the need to increase the height of the railway.
"We fully intend to recreate the character of the area after construction. Our hope is to provide more diverse and extensive habitat areas than there are at present."
Nick Hillard, secretary of the Crackley Residents' Association, said: "The whole area, one of the thinnest green belts in the country is going to have to be dug up... this highlights the potentially catastrophic unforeseen consequences of HS2 [construction] which have formed no part of any public consultation to date.
"This situation will undoubtedly be replicated up and down the line as more detailed information becomes available to the HS2 engineers."
The high-speed rail network was given the go-ahead by the government in January and it is expected phase one, between London and Birmingham, should be running by 2026.
Ministers say the railway will stimulate regional economies, and it has been welcomed by some business leaders.