Work on a £4 million revamp of Leicester's Belgrave Circle is now set to run into the new year.
Council bosses had originally hoped to have the scheme, which began with the demolition of the 1970s flyover, complete by October, but now it is expected to take until March.
However, they have said work will be stopped in October to allow the annual Diwali celebrations to take place.
The project is being entirely funded by Sainsbury's as part of a deal that saw the supermarket giant granted permission to relocate from its Belgrave store to a bigger outlet in Rushey Mead.
The council's head of highways, Martin Fletcher, admitted the project had taken "a little bit longer" than anticipated.
He said: "When the flyover was finished, we took stock. We decided to add some extra capacity and put in additional lanes.
"Belgrave Circle is not only a major traffic junction but also a major utilities junction.
"We have major sewers going out of Leicester to Wanlip. We have gas and water mains together with high-voltage electricity and telecommunications cables. It has been complicated."
Concerns have been raised that Diwali celebrations will take place in a building site, but Mr Fletcher said the works in the footprint of the flyover, on the main carriageway, would be complete by then.
Work will stop on October 10 for the Diwali lights switch-on, starting again on October 13.
There will be a further break from noon on October 22 until October 27 for the Diwali Day celebrations.
Mr Fletcher said: "There will be a bit of safety fencing around, but by the time Diwali arrives we will have new lighting columns down to the circle island in place carrying Diwali decorations. It will look great.
There will be some lane restrictions during the work, at times reducing to one lane in either direction, but there are no planned road closures. All work will take place between about 7.30am and 5.30pm.
After Diwali, the remaining work will be carried out at Belgrave Gate, to the south of Belgrave Circle.
This will include the creation of car parking, some alterations to footways on the Abbey Park Street side of Belgrave Circle and work on the central reservation to the south of the old flyover.
Mayor Sir Peter Soulsby said: "This is a major project which is vastly improving this part of Belgrave and reconnecting the Golden Mile to the rest of the city.
"This latest stage of work will be done with the same attention to detail as the removal of the flyover earlier this year, where careful traffic management and planning helped it run smoothly with the minimum of disruption to motorists.
"The Diwali celebrations on the Golden Mile in October are among the best in the world, so we will ensure the majority of the works are complete by then, so that the festivities can take place as normal.
"The remaining works will then be completed afterwards and the entire project completed by spring 2015.
"We are very grateful to the businesses and residents in the area near the works for bearing with us, and can assure them the end result will be worth the wait."
