The controversial Lower Thames Crossing is a “smart motorway by stealth,” campaigners have claimed.

Thames Crossing Action Group has written to the government calling for the £10bn project to be shelved.

But Lower Thames Crossing bosses argue congestion will be eased at the Dartford Crossing and create a new reliable route.

The government has accepted plans for the crossing which will now be examined by a panel of government appointed independent experts.

Work on the two new 2.5-mile (4km) tunnels under the Thames could start as early as 2024, if the project gets the go ahead.

But, given the government paused its roll out of smart motorways last January over safety fears, campaigners believe that should put the brakes on the new scheme.

One document highlights that the proposed new crossing "would operate with no hard shoulder but would feature a 1m hard strip on either side of the carriageway".

It would also feature technology including stopped vehicle and incident detection, lane control, variable speed limits and electronic signage and signalling.

In their letter to the Transport Secretary, Mark Harper MP and Roads Minister, Richard Holden MP the action group said this information shows that the proposed LTC would be a smart motorway by stealth.

Speaking today, Laura Blake, of the Thames Crossing Action Group, said: “Since the government has paused the roll out of smart motorways, the proposed crossing should be paused now in keeping with that decision.

“Obviously there are many other reasons why we feel the proposal should be scrapped - it would be so hugely destructive and harmful.”

The campaigner took umbrage over future carbon emissions, claiming the current plans “would not be compliant with net zero,” targets.

“Right now the very least we need them to do is to pause the project on the grounds it is a smart motorway by stealth," she added.

The planning process is likely to take about 16 months including six months of examination, with some taking place at public hearings.

And the project requires changes to the current road network and requires approval from the government in the form of a development consent order.

The proposals have come under fire over eco-credentials and whether it provides taxpayers with value for money.

Last year, National Highways said the crossing would double road capacity across the Thames east of London and reduce congestion at the Dartford Crossing.