A shopowner claims his takings have plummeted by more than 80% as a result of a scheme by Powys council to improve safety for shoppers in a town centre.
Only buses and taxis can exit the Bulwark in Brecon
As part of a new relief road opened last June, the council shut Brecon's Bulwark except for buses and taxis.
Shop owner Peter Casaru said the move had hit trade, and a nearby two-hour supermarket carpark did not leave people enough time to explore the town.
The council said the relief road would provide long-term benefits to Brecon.
Last November, some shops in the Bulwark refused to pay business rates in protest at the move, which they claimed was "crippling trade".
Shopkeepers said the road closure confused visitors and diverted passing trade away from their shops.
But the council said the move reduced traffic and improved safety for shoppers.
Mr Casaru, who runs digital imaging centre in Lion Yard, said last year his takings averaged between £800 and £1,400 a day but they were now down to £130.
"Retailers' trading figures in the town have plummeted, and no one seems to care," he said.
"I too have been affected by the new scheme, but I believe I have discovered why the trade has gone down - more than 80% in my case.
"Two hours parking doesn't allow shoppers time to do their food shops and then visit other retail outlets. The town centre off-street parking has now been reduced to 30 minutes."
Other shops said a fall in passing trade had seen their sales drop too.
Ian Dent, who owns the A-Frame Gallery in the Bulwark, said: "I stopped paying my business rates for six months in protest. The situation in the Bulwark hasn't improved."
A Powys council spokesman said: "The £3.5m inner relief road aims to provide long-term benefits to Brecon town centre, reducing traffic in the centre, improve pedestrian safety and provide a public transport interchange.
"There are more car parking spaces since the refurbishment in the town. We have a mixture of short stay and long stay within reasonable walking distance of the town centre."