A delay on plans to close a Castle Cary road for 19 weeks will “have a serious impact” on the town’s annual carnival.
Part of the A371 near Castle Cary Railway Station will be closed between July and November next year.
Network Rail originally planned to close the road to carry out engineering work on Ansford Bridge this autumn.
This was then delayed until January, but has now been put further back to July after a meeting with local authorities and businesses.
Somerset County Council has given Network Rail a window between July 8 and December 1, 2013, to complete the work.
A 19-week road closure will take place from July 8 until November 1, which will clash with the Castle Cary carnivals on October 5 and 12.
After this, a single-file traffic management scheme will be in place until December 1.
Gordon Stockman, Castle Cary and Ansford Carnival Committee president, said: “This road closure will have a very serious impact on our carnival. We have float entries that come from Shepton Mallet, Frome and all around the Mendip area who will have serious difficulties getting to us.
“Carnivals in Somerset bring in around a million pounds of revenue for local businesses each year, not to mention they raise well over £100,000 for local charities.
“It’s so very important. Yeovil carnival sadly no longer exists and Wincanton carnival no longer exists – we need to support the carnivals.”
Mr Stockman said it would cause particular problems for the town’s award-winning, 100ft long Cary Comedians float, which can only travel on certain roads.
He said it would also have an impact on other carnivals and he will be objecting to the new planned dates.
John Baker, Network Rail’s media relations manager for Wales and West, said: “We had a productive meeting with the elected representatives and businesses, and two hours before the meeting Somerset County Council informed us we had a window of opportunity to do the work from July 8 to December 1, 2013.
“We now need to go away and understand the impact this will have on our programme and on the local community. The work will miss the Bath and West Show and the Glastonbury festival, but will affect Castle Cary Carnival.
“We have to work within our window of opportunity. It will always be difficult to please everyone.”
Mr Baker said work was necessary as it is not within their budget to build a new bridge at a cost of £1m.
Somerset County Council said these dates have been selected to fit in with other scheduled works in the area during the year.
Part of the A371 between Castle Cary and Wincanton will also be closed on week days for three weeks from October 31 to prepare the drains for winter.
Local resident Phil Merritt said: “I find it incredible that those in charge of our roads can contemplate a complete closure of an A road for such a long time.”