Drivers are advised of delays and some road closures ahead of the Sonisphere music festival at Knebworth Park next weekend.
Thousands of people are due at the event between Thursday (July 3) and Monday, July 7, and congestion is expected on the A1M and around Stevenage and Knebworth.
Drivers will need to use the A1M junction 7 to access the site, which is different to previous events at the location.
Southbound traffic should leave the motorway at junction 8 and go along the A602 Hitchin Road, A1072 Gunnels Wood Road and A602 Broadhall Way.
Northbound motorists can use junction 7 left turn into the venue.
Westbound traffic should use the A602 into the venue via A1m junction 7 and eastbound should use A602 to A1m junction 8 then follow signs as per southbound traffic.
To leave the venue motorists should take the Novatel Road onto A1m junction 7 roundabout and access the A1m southbound or A602 eastbound. Alternatively, drivers can leave the site through Deer Gate and go onto Old Knebworth Lane, then the B197 London Road and follow signs to A1m junction 7 for the A1 south or A1m junction 8 for A1 north.
The Highways Agency and Hertfordshire Constabulary have been working together to advise drivers to plan and check their travel routes in advance.
Members of the public should contact the Highways Agency Information Line on 0300 123 5000
Journalists should contact the Highways Agency press office on 0844 693 1448 and use the menu to speak to the most appropriate press officer