The lights at the junction of Wragby Road and Ruskin Avenue are to be replaced because they are now so old they are likely to begin to fail.
This means drivers who usually use Ruskin Avenue as a cut-through from either the bypass or estates in the north of the city will instead be sent along Outer Circle Drive – an area prone to long traffic queues.
Temporary traffic lights are to be set up from today, with the main work starting on July 30.
Tim Clark, acting principal engineer at Lincolnshire County Council, said: "The traffic signals are essential for the safety of pedestrians and motorists at this busy junction.
"The current installation is more than 25 years old and has reached the point where failures are much more likely and some parts are now difficult to replace.
"The new installation will be fitted with the latest technology available. It will have improved facilities for pedestrians, it will be cheaper to maintain and will use less electricity.
"We apologise for any inconvenience caused by the closure, but this will enable the works to be completed in less time."
The road will be shut from the Wragby Road entrance up to Ruskin Green so contractors can work safely on the £120,000 upgrade.
Some work will take place on pedestrian paths, but a safe route around will be provided, said Mr Clark.
The refurbishment includes the removal of the old signal equipment including existing cables, installing new ducting on the footways, resurfacing the existing carriageway and installing new kit.
But residents are not happy with the plans. Motorist Dave Jassie, 59, of Outer Circle Drive, said he felt his road was already badly congested.
He said: "I cannot see why traffic is being diverted down here. It's bad enough already. The other night it took me five minutes to get off my drive. It would be better to divert traffic via the bypass."
Stay-at-home dad-of-two Winston Dunbar, 44, of Ruskin Green, added: "It will be an inconvenience because we rely on public transport and during the roadworks the nearest bus stop will be on Macaulay Drive.
"I think the traffic lights that are already there do their job, so if it's not broke why fix it?"