Chief Inspector Kevin Greenhow told ITV Border:
"The event has grown and grown and we're expecting in excess of 40,000 people over the course of the Fair. We're asking motorists throughout the North of England and South Scotland to be aware that there will be carriages and caravans on the road and they must be passed with caution.
Respect other road users and be patient. Last year was successful and safe, let's have the same again this year."
More top news
Chilly start. Some frost in places, icy patches possible too. Cloud and sunny spells today, hazier in the west later
Emma Jesson brings you Sunday night's forecast
Not alot of rain in the forecast outlook, but remaining cloudy. Temperatures average by day and above freezing by night