The leader of Southampton City Council has said he believes most drivers will pay for parking - despite all the city's traffic wardens going on strike.
They are striking for a week from 31 May as part of "rolling" industrial action by city council workers.
The council said managers could be used to empty parking machines and issue tickets during the action.
But a Unison spokesman said they would not have the training or the authority to stand in for the wardens.
Royston Smith, leader of the Conservative-run council, said: "I am confident that the majority of people will abide by the parking rules in the city next week.
"Southampton residents are law-abiding, honest people.
"Anyone using council parking facilities next week is required to pay for parking."
He asked residents to remember parking was an important source of council income, bringing in about £100,000 a week.
Andy Straker, from Unison, said of the council's 40 traffic workers, all but two were members of either Unison or Unite.
"Our understanding is every single one is coming out [on strike]," he said. He explained that the two non-union workers were on long-term sick leave.
Mr Straker added: "Councillor Smith can say all he likes and make all the threats he like but they [council managers] won't have the training and they won't have the authority.
"They have to know the law."
The industrial action is being held in a bid to stop proposed pay cuts of up to 5.5%.