The traffic light staging at the Tebourba Way and Romsey Road junction was changed in January to improve right turns at the junction, with the council saying this was due to reports of accidents.
However, this led to an increase in congestion in the area, with Cllr Jeremy Moulton criticising the impact on residents.
On February 5, the council confirmed the changes would be monitored for a fortnight, before a decision would be made on whether to revert to the original phasing or consider an alternative option.
Southampton City Council have now confirmed no change will be made.
Cllr Moulton said: “This decision has come four weeks after the original two week period that was promised.
“It’s a disappointing decision and it’s disappointing that I had to raise it in a full council meeting to get an answer.
“This change has caused unnecessary traffic congestion and has affected people getting about, doing the school run and going to work.”
He added: “Millions of people use that junction every year, it’s a main route into the city and connects to the hospitals.
“I think it’s an overreaction, the number of accidents have been tiny compared with the enormous volume of traffic.”
Cllr Moulton said, according to the data, there has been one right-turn accident for every 750,000 right turns at the junction.
A spokesperson for Southampton City Council said: “At the Romsey Road/Tebourba Way junction, a significant number of incidents were recorded over a five‑year period, with several directly linked to right‑turning movements.
“A detailed study and traffic signal modelling exercise recommended introducing separate signal phases for the two Romsey Road arms.
“This revised phasing was implemented, monitored and reviewed during a trial period.
“Throughout the trial, driver safety remained the council’s priority, and the level of queuing observed aligned with the modelling predictions.
“Based on this evidence, the recommendation was to keep the revised signal operation in place.
“However, the junction continues to be actively monitored by the traffic signals team, who will respond to any changes in conditions should they arise.
“So far, there has been little need for further alterations.”
“Since the opening of Winchester Road after the urgent SGN works, we have continued to monitor the junction and make improvements ensuring continuous flow where possible post works.”