Jersey's Chamber of Commerce has warned of major implications if current plans for the 75th anniversary of Liberation Day go ahead.
The link road between Liberation Square and Weighbridge Place is due to close so the two spaces can merge.
Infrastructure Minister Deputy Kevin Lewis has said businesses in the area are 'largely happy' with what is proposed - but the Chamber of Commerce disputes that.
Andy Jehan thinks the plans are 'rushed' and says the government needs to realise the major consequences this will cause.
"There's been a distinct lack of consultation. Yes we've got the planning process to go through, but the impact of closing the roads with more people coming to work down at the Esplanade and the Finance Centre we believe is very disappointing.
"To consider double-decker buses maneuvering through the centre of town as opposed to coming through the little slip road that they do at the moment we think is open to problems."
The Jersey Taxi Drivers Association has also spoken out against the plan. It is warning of price rises of £2.42 or more to passengers heading east if drivers can't use the link road.
Domino Cabs owner Ian Le Gallais says he's very unhappy with the lack of consultation so far.
"“Before launching such plans, Taxi drivers and businesses that regularly have to deliver through St Helier should have been consulted. The impression we get is this is a foregone conclusion.
"It is also disappointing that there is a lack of any consideration to increasing the taxi spaces in the areas, despite rank drivers having asked for this for a long time."
Deputy Susie Pinel revealed in the States Assembly that the project will cost around £3m, which is £1m over budget.
The plans will go on show at Jersey Museum tomorrow (Tuesday 19th March).
However the Chamber of Commerce wants an urgent review and 'further thinking' on the proposals.
"This plan would be significantly disruptive to the flow of traffic around Hill Street and the Pomme d’Or Hotel for what I can see is of little benefit. Sending double-decker buses around the block will only increase the risk of accidents, on top of the additional time spent on the loop around Hill Street. Sending traffic up Pier Road, instead of having access to the tunnel, which was built and designed to ease traffic heading east, will cause more issues, just when Havre des Pas is looking to bring in a one-way system facing the other way.
Personally, I just don’t see the benefit of the current plan when weighed against the disruption, delays and frustration it will cause. For the few events that we have during the year that would require the joined-up space, we can close the intervening road like we have been doing. With regard to the re-routing buses, changes to send these through the town centre to access to the bus station does concern me on safety issues. Here we have a project that is already scheduled to cost an additional £1m, that is being rushed through.
"The normal engagement process used for other traffic changes being cast aside on this occasion without and thoughts on the impacts to the retail heart of our island. Giving the impression in a Government press release that everyone is happy with these plans is, at best, disingenuous." - Eliot Lincoln - Chamber President.