The use of a car park by travellers has been defended by one of the men living at the site.
Bus services to the park and ride in Bicester, Oxfordshire, have been suspended by Stagecoach following the travellers' arrival on 5 April.
It is the fourth time a group has moved on to a park-and-ride site in the county this year.
A spokesperson for the group called Dennis said they were there because of a lack of official traveller sites.
He told the BBC they were from the same family and had camped in 35 different locations this year, including sites in Birmingham, Coventry and London.
They were at Water Eaton park and ride on the outskirts of Oxford last week and previously camped at the Redbridge and Peartree park-and-ride sites in Oxford.
Dennis said they chose the sites as they were quite big and away from town, adding Oxfordshire was a nice area.
When asked about disruption, he accepted it caused inconvenience but said they tried to only use the perimeter of the site to leave the middle free for cars.
On Wednesday, Oxfordshire County Council said it was "working towards returning the park-and-ride site to normal operation".
"This may involve using powers available to us," a spokesperson added.
The Ministry of Housing, Communities & Local Government said the number of traveller caravans on authorised sites had increased since 2010.
But it added figures showed 16% of all caravans are on unauthorised sites, and a review of the laws to deal with such sites was announced by housing minister, Dominc Raab, last week.