Lorries are taking short cuts through a housing estate in Moulsecoomb despite a promise that they would stick to a safer route during building work for the new Falmer Academy.
Residents have raised the matter at community group meetings.
They also signed a petition because they are unhappy about the dangers, particularly because the streets are so narrow on the estate.
Conservative councillor Maria Caulfield, who represents Moulsecoomb and Bevendean on Brighton and Hove City Council, gave her backing to worried residents.
She said: “Many months ago when plans were discussed with local residents a promise was made that no site vehicles would go through the estate.
“But this promise has not been kept and residents fear for the safety of locals as a result of heavy lorries now using small and narrow local streets.”
She said that the matter had been drawn to the attention of the contractors who were trying to address residents’ concerns.
Among their complaints was the state of the road, which is now being washed down beyond the site entrance.
