The Highways Agency is pleased with the proportion of motorists paying the new Dart Charge – despite the fact around 300,000 journeys have not been paid for.

Of the roughly two million crossings made between the 6am to 10pm chargeable period since the scheme went live on November 30, 85 per cent have been paid for.

According to a Highways Agency spokesman the proportion is significantly above the average for the same stage of similar projects around the world.

But it still means 15 per cent of journeys in the tunnels or across the QEII Bridge, have not been paid for when they should have been.

Despite this the agency team is said to be pleased with the figures so far, though the target of 93 per cent of journeys being paid for once the scheme has bedded in, is some way off.

One million vehicles are now registered to Dart Charge accounts, and the Highways Agency claims average journey times have been significantly reduced.

According to new figures, between 7am and 7pm it now takes on average nine-and-a-half minutes less to cross the Thames southbound that it did before Dart Charge was introduced.

The figure for those using the tunnels to travel northbound into Essex is four minutes 11 seconds less.

The figures compare average journey times from the end of November against average times during the first two weeks of December.

The Highways Agency has also announced that first time offenders who haven’t paid for a journey can avoid a fine if they do so within 14 days of receiving a penalty charge notice in the post.

The announcement comes as the first 10,000 PCNs covering roughly the first full day of the scheme on December 1, were sent out to motorists.

The measure is likely to be in place for the foreseeable future.

The normal penalty for using the crossing without paying is a £70 fine, which can be avoided if you settle the debt before midnight the day after your crossing.

The £70 is reduced to £35 if paid within 14 days of the PCN being issued, but it rises to £105 if not paid within 28 days.

Dart Charge project director Nigel Gray said: "Dart Charge is off to a fantastic start, and I’m really encouraged that more than a million vehicles have been registered for accounts.

"Traffic flow is going well too and there has been a real improvement in journeys, especially southbound where drivers no longer have to stop at a barrier at all.

"We want to give all drivers the opportunity to pay and comply with the scheme.

"That’s why the first penalty charge notice issued for any vehicle for non-payment of the charge will offer the driver an extra 14 days to pay – and pay for any crossings they have made since.

"This measured approach strikes the right balance between being clear to drivers they need to pay Dart Charge and giving them every opportunity to do so."

The scheme has replaced fixed toll booths with ANPR cameras which record whenever a car uses the tunnels or the bridge.

The charge is payable through a pre-paid account set up online, by phone or by post.

One-off payments can also be made at one of more than 18,000 Payzone retail outlets.

It costs £2.50 to use the crossing in a car, £3 in a twin-axle goods vehicle or £6 in a multi-axle goods vehicle.