The Highways Agency has announced that the new barrier-free Dartford Crossing will now come into effect in late November — not this month, as originally planned.

The Web site, systems and infrastructure needed to operate the new arrangements have been installed and are being tested to ensure that they operate reliably and are easy to use.

Highways Agency project leader Nigel Gray said: “Dart Charge is a massive change for drivers using the Dartford Crossing; it’s only right that it is thoroughly tested before being introduced. We want to help drivers to be ready for the improvements we’re making at the Crossing. That’s why we are saying today that Dart Charge will start during late November.

"We can reassure drivers that we’ll give them plenty of notice before the changes are introduced. They will have considerable time to sign up for a pre-pay account, which for most will be the easiest and cheapest way to pay the charge — with discounts of up to a third on every crossing.”

The full changes to the road layout will be finished by the end of April. Further details about registering for pre-pay accounts are still to be announced, but drivers will be able to pay through a range of methods, including phone, text, on-line and at shops.

It is hoped that the new system, which in theory means no more queues and barriers, will improve traffic flow at the river crossing for the 140,000-150,000 vehicles that use it each day.