Highways England has advised drivers using the M5 in Gloucestershire to plan ahead and allow extra travelling time during the four-day horse racing festival.
The popular event runs from today until Friday, with more than 200,000 people expected to attend throughout the week.
The Festival concludes with the Gold Cup which can see more than 65,000 people attend on a single day.
The busiest times on the roads are expected to be between 9.30am until 12.30pm each day.
Queues are likely on the approach to M5 junction 10 southbound, and on all approaches to M5 junction 11.
Members of the public should contact the Highways England customer contact centre on 0300 123 5000.
Journalists should contact the Highways England press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer.