The force had already made 30 arrests for “low-level offences”, Det Supt St Quintin said, mostly for drink and drug driving offences.
He added patrols would be stepped up on Friday and Saturday, when the event was expected to be at its busiest, and he urged people to be cautious when driving to the fair.
“We are expecting lots of slow-moving vehicles, so people do need to take it steady on the roads and be patient,” he said.
During the event, police will also be asking people if they would back plans to use facial recognition software cameras to help catch criminals at future fairs.
Det Supt St Quintin said the technology had the potential to have a “profoundly positive impact” on keeping people safe by identifying suspects, as well as vulnerable and missing people.
