LIVERPOOL city centre's major route to the new Paradise Street bus station is to close for almost a year and a half from next month.
The latest phase of the Big Dig will mean hundreds of buses a day having to be re-routed during a full shutdown of Hanover Street and virtually all of Ranelagh Street.
A combination of work by Grosvenor, United Utilities and gas company National Grid will lead to the road closures starting near the end of July.
Last night, Liverpool Chamber of Commerce transport spokesman Steve Pearse said businesses along the closure route were already expressing "deep concerns" about the impact of the measure.
The city's two major bus operators, Arriva and Stagecoach, have had to devise plans for buses that normally use Hanover Street to reach the multi-million pound transport interchange at Canning Place.
The closure will affect half of the buses that currently use the new interchange.
It is expected that buses will start and terminate around Great Charlotte Street and Lime Street, as well as Skelhorne Street, for the duration of the closures. Grosvenor's Paradise Street project director Rodney Holmes said bus operators had rejected a proposal for signal-controlled one-way traffic along Hanover Street during the work.
He said: "That street is therefore going to be closed to all vehicles, except those that have to cross it to serve existing businesses, from the start of work by United Utilities at the end of July through to the end of Paradise Project work at the end of next year."
Mr Holmes said pedestrian access along the whole length of Hanover Street will be maintained throughout the period of the closure to traffic.
Mr Pearse added: "This is one of those occasions where the work has to be done and there are few options for traffic diversions.
"There had been discussions about keeping one lane opened, but that would have significantly increased the contract period and mean problems for a longer period."