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
Looking a little less cold into the long weekend with some sunshine. Wind, rain & showers in the mix too. Here's the detail.....
Bungling Martin Bainbridge attempted three armed robberies in Carlisle, brandishing a knife wrapped in a tea towel.
The 24-year-old started three separate fires at a major Cumbrian tourist attraction, and caused more than £500,000 of damage.