Angry motorists have found themselves trapped in car parks for up to an hour as the new Mill Way road layout causes chaos.
One shopper says he had to abandon his car at the weekend and walk to the railway station where he caught a taxi home – returning hours later when the congestion had cleared.
Problems have been going on for weeks following the revamp of the road network as part of the Morrisons’ development.
But issues came to a head last Saturday afternoon as thousands of people visited the new store and the nearby Sittingbourne Retail Park.
Those stuck say traffic lights, which have replaced the roundabout, seem to have been wrongly phased and the road layout failed to cope with so much traffic.
Highways chiefs say they will monitor the situation around the new Mill Way road layout and make changes if needed.
The pledge comes after weeks of frustration came to a head at the weekend.
The area was so swamped, motorists were left trying to escape the car parks for up to an hour and surrounding roads were jammed.
Shopper Michael Peters said: “Rather than join the queues and sit there, wasting precious time with my engine running for ages, I abandoned my car, steamed off to the railway station and took a taxi home.
“With traffic blocking both lanes in front and behind people, the famous British patience was being tried to the utmost.”
“In the evening after the shops had shut, whilst striding back to collect my vehicle, I pondered on the thousands of hours, wasted by hordes of people trapped in those long queues since all this started.”
Despite Morrisons opening on January 28, temporary traffic lights remained in place until the permanent ones were switched on last Thursday.
However, less than 24 hours after going live the signals were down for an hour after the power supply was disconnected.
KCC’s highways transport and development manager, Nasser Sarrafan, said: “The works on Mill Way to build an entrance to the new Morrisons’ site were carried out by a contractor on behalf of the supermarket chain.
“Power for the two sets of traffic lights, at Crown Quay Lane and Mill Way, was cut for a time on Friday afternoon when the energy supplier disconnected them.
“In terms of the road scheme layout, a final assessment will be made to make sure it is working as planned and as efficiently as possible. This audit will identify any necessary changes or modifications.”
Motorist Graham Jones, who was also trapped on Saturday, said: “The whole area is becoming a no-go zone. Businesses must be losing a fortune.
“Plus Chalkwell Road is experiencing extra traffic it can’t cope with as people avoid the retail park and Morrisons.”
Some people, including borough Labour leader, Cllr Roger Truelove, believed the traffic flowed better while the lights were out of action.
A Morrisons' spokesman said: “KCC designed and approved the new road layout and contractors simply implemented it.
“The timings for the signals are also the responsibility of the council who are able to monitor and adjust them.”
Gordon Henderson MP says he wants to see the present traffic light phasing changed as a matter of urgency.
He said: “I would also like to see the inside lane heading west past Morrisons changed to access to the store, rather than allowing straight ahead traffic as it does now.
“I think those who designed the junction missed a trick by not adding in an east-bound slip road out of the retail park.
“There is plenty of room for such a road, but instead they have constructed two footpaths. That was a mistake.”
County and borough councillor Mike Whiting says the traffic situation has been a nightmare for local businesses and motorists.
He said: “I will be closely monitoring the situation and if necessary will demand the reinstatement of the roundabout.”
Labour leader Cllr Roger Truelove said: “The developers withdrew their earlier commitment to a pedestrian flyover from the mill site to the retail park. That prompted KCC to put in lights instead of the roundabout.
He said simply restoring the roundabout would cause difficulties, adding: “Sittingbourne town centre needs the completion of the northern relief road.”