TRAFFIC jams must be at least 12 miles long before toll barriers at the Dartford Crossing are lifted.

The barriers will also only be lifted in an emergency situation and if traffic is travelling at a continuous speed of 10mph.

It means jams would have to start from junction 28 on the M25 in Essex and from junction 4 in Kent. Drivers and business leaders have labelled the rules “ridiculous”.

Rob Nordon, company secretary for Canute Lorries, in Purfleet, said: “The conditions they have set are ridiculous. Traffic regularly queues back to junction 28 every Friday and it is because the tolls are there.

“They keep them in place because of the money it brings in. A common sense approach is needed to this.”

A six-month trial was launched at the beginning of June by the Highways Agency and M25 operator, Connect Plus, to suspend the charges at times of severe congestion.

However, the trial has already been tested when the tolls remained in place even though a lorry broke down on the bridge and caused 11 miles of tailbacks.

Transport minister Mike Penning came under fire for not insisting the barriers were lifted, but the conditions have now been clarified.

Iain Wicks, chairman of Essex Federation of Small Business, said: “Within 13 hours of the decision becoming effective, Mr Penning had broken his promise and his performance has not improved since.

“On July 16 a lorry broke down on the bridge closing two lanes and despite the trigger marker being reached, once again the tolls were still being collected even though vehicles had to queue for two hours.”

Motorists are also facing price hikes at the tolls. The proposed changes would see charges rise from £1.50 to £2 later this year and then up to £2.50 by next spring.

Mr Wicks added: “We will be continuing to monitor how many times traffic reaches the trigger point and the tolls continue to be collected in defiance of the minister’s promise.

“We hope this will be the last time that promise is broken, but suspect the list will be considerable by the time the pilot project ends in six months’ time.”

A spokeswoman for the Highways Agency confirmed since the trial was introduced the tolls have not been suspended.