The traffic lights are expected to remain in place until 29 May.
Nolan said it was the fourth collapsed sewer in Canterbury, according to the Local Democracy Reporting Service.
“I was coming back from the coast, and I was caught in traffic from the top of St Thomas’ Hill,” she said.
“The whole of St Dunstan’s was crawling. London Road roundabout and Pin Hill were completely clogged.”
She urged the company to be “transparent” about the reasons for the collapse and if its maintenance schedule “needed to be improved”.
“It’s been an unacceptable inconvenience to local people travelling to work or taking children to school for their exams,” Nolan added.