A double warning has been issued by authorities ahead of this weekend’s V Festival in Chelmsford.

Essex County Council is urging motorists to avoid the area around the festival venue at Hylands Park while revellers travel to and from the music event.

County Hall is also sending a message to festival goers to not take so-called legal highs as they may not be good for their health.

There are concerns that the drugs, specifically designed to avoid legal bans, have unknown ingredients and unknown effects – especially when mixed with alcohol.

Open Road, commissioned by Essex County Council’s drug and alcohol team, will be on site during the festival offering support for the ninth year running.

Joni Thompson, treatment and quality manager at Open Road, said: “We’ll be on hand not only to provide welfare and safety services to any festival goers that need help, but also to reduce the impact of drugs and welfare issues on the festival medics.

“Our advice would be that even if you think you know what you’re buying, you can never really be sure. If you don’t know what it is, don’t take it.

Essex Police has already issued a public space protection order for the festival meaning anyone found selling, distributing or consuming legal highs can be fined, arrested and potentially evicted from the festival.

Anne Brown, county councillor for healthy living, added: “We want festival-goers to have fun, but to make healthy and informed choices and not risk their lives.

“Legal highs or nitrous oxide can result in serious side effects.”

More than 10,000 vehicles are expected to arrive at this year’s V Festival, with Monday August 24 expected to be the worst day as 50,000 people leave the event.

The A414 will be closed along Three Mile Hill, linking to the A12 junction 15, to minimise congestion on the day.

A 30mph speed limit will also be in force from Friday until Monday to improve safety.

Eddie Johnson, county councillor for highways maintenance and small schemes, said: “Our traffic management team has gained 20 years’ experience of supervising V Festival road movements. This has included working closely with the organisers and developing contingency plans to meet most eventualities, including a complete closure of the A12.

If you are worried about the effects of drugs during V Festival contact Open Road on 07532 095219.