Drivers parking on new pavements in the centre of Preston have been warned they could face a £70 penalty charge notice, after dozens were issued on Sunday.
Enforcement has been stepped up to coincide with the latest stage of work, with signs showing the parking restrictions in place.
County Hall bosses said more than 30 penalty charge notices were issued over four-and-a-half hours at the weekend.
John Fillis, cabinet member for highways and transport for Lancashire County Council, said: “It’s important that people always park their vehicles responsibly.
“During this work there have been times where people have parked inconsiderately, especially on the pavement.
“This blocks pathways for people shopping, working and getting around the city centre and causes particular problems for people with a visual impairment.
“It can also damage the paving, which would mean costly bills if we had to replace it.
“We’re delighted that this latest stage of work has been completed, which has given a new-look to this area of the city, but we want to make sure that it’s kept in good condition for everyone to enjoy and benefit from.
“There is a lot of investment in the city centre and it is no surprise that more people will want to come and spend time here.
“There are many great car parks around the city centre, as well as the park and rides, so I would urge visitors to use these instead of the new pavements.”