Tenby could become a "no-go area" for tourists in the summer months without a town centre ban on cars, a public inquiry has been told.
The public inquiry into the traffic ban is scheduled to last four days
Arguments for the pros and cons of the controversial traffic scheme have begun at a hearing in the town.
For four years an experimental order has kept vehicles off Tenby's streets during most of July and August.
Pembrokeshire Council says it makes the resort safer, but opponents argue that the restrictions are excessive.
During the next four days planning inspector Clive Nield will hear evidence from close to 20 people on both sides of the debate.
Opening the inquiry, he said: "It seems to me almost everyone supports the principle of limiting traffic during the summer months.
"It's the details about how it would be operated that are in dispute here."
The fight against the scheme has been led by Tenby Walled Town Residents Association, which argues the ban penalises residents and businesses who live within the town's medieval walls.
First to give evidence was Ian Westly, director of transport and environment for Pembrokeshire Council, who said there was a balancing act between cutting traffic and causing minimum disruption for residents and businesses.
He said restricting traffic within the walled area had been a challenge facing councils for the last 50 years and without action there was the "potential for Tenby to become a no-go area for tourists".
Mr Westly said: "It's extremely difficult, if not impossible, to arrive at a scheme that will satisfy everyone from the outset. It's certainly not our intention to impart hardship in any way on people."
The Pembrokeshire National Park Authority and chamber of trade will also speak in favour of the scheme.
It uses fixed cameras to read the number plates of all vehicles entering the ban area and those not on the approved list are sent fines through the post.
Residents with their own off-road parking space are allowed one journey a day within the restricted hours of 1100BST and 1700BST and are given concessions at council run car parks.
Arrangements are made to accommodate weddings and funerals, and boat owners are allowed access to the harbour.
There are more than 500 homes and 300 businesses within the walled town.
The council ran the ban on an experimental basis in the past, but after it advertised its intention to make it a permanent fixture it received 63 objections, forcing this week's hearing.
Later in the week the inquiry will hear from businesses, residents and harbour users who claim the ban is too restrictive.
The town council clerk, sailing club, harbour users and Caldey Island Estate Company will also speak against the scheme.
They will argue that properties within the walled area should be allowed access to off-road parking throughout the day.