Formal objections have now been lodged against the £2 million Smart corridor scheme in St James just weeks before works are due to start - including one from a PCSO.
Northamptonshire County Council is due to start construction work on the scheme on January 4, claiming measures such as introducing live traffic update displays and new bus stops would improve traffic flow on the clogged roads.
But the St James Residents Association says one measure - to ban those turning left from Spencer Bridge Road into Weedon Road - will create traffic chaos.
It has now formally objected to the proposal on the grounds that getting rid of the turn would force people to use the 'Scottish' residential streets as rat runs.
It has been joined in doing so by both county councillors for the area, and even a local PCSO.
The association has called on the council, which had contracted Kier WSP to carry out the work, to fully consult with the people on those streets before ploughing ahead.
In its objection to the scheme, the association, said: "Most will use the Scottish streets as a rat run, which will bring them out further down the Weedon road via Glasgow Street, effectively just moving the problem elsewhere by around 400 yards - and to the annoyance of those residents in the Scottish streets.
It adds: "Residents in the streets named above would experience a deterioration in their quality of life even further, by the extra traffic which will use their roads as rat runs and those who live in Abbey Street and those surrounding streets, will be massively inconvenienced by the plan."
There are also real concerns over the construction phase of the scheme, which will see a right turn from Weedon Road onto Harlestone Road closed off for around three months.
This will coincide with the major gas works to Gold Street, Woolmonger Street and Horseshoe Street - expected to last 13 weeks.
Chairman of the St James Residents' Association, Graham Croucher, said running the two major roadworks simultaneously could bring the town centre to a standstill.
A spokesman for the county council said closing the left turn from Spencer Bridge Road into Weedon Road will improve traffic flow in the area.
He said: "It is intended to ban this turn in the final scheme to increase the capacity of this junction and [this] means that pedestrians have a much safer route at this junction."