Motorists in Northampton are being warned to expect delays at the busy junction where Wellingborough Road meets Abington Avenue for the next six weeks.
Northamptonshire County Council is due to start work on installing new traffic lights that will be more responsive to changes in traffic flows and help vehicles flow more easily.
Work has been underway for some weeks, using existing traffic lights with lane-closures kept to off-peak periods.
However, from Monday, the whole junction will be under the management of temporary traffic lights with lanes on all approach roads reduced to single lanes, leading to delays for motorists.
A spokesman for the county council said: “The current traffic lights have been in place for about 20 years, using old technology which means it is more difficult to change the phasing in response to changing traffic volumes.
“This final phase of the works are scheduled to last for about six weeks – coinciding with the school summer holidays, the quietest time of year on the roads.
“Motorists are advised to, if possible, seek alternative routes while the work is taking place and allow extra time for their journeys.”