Plans to build Britain’s longest road tunnel – which have been in the works for 15 years without any progress – have cost £300 million so far.

The Lower Thames Crossing, which was proposed to ease congestion on the Dartford Crossing, would connect Kent and Essex.

It is expected to cost around £9bn for the whole 2.4-mile project, which would be built in Gravesend.

Recently, it was revealed the development is the longest planning application on record with a whopping 359,866 pages spread over 2,838 separate documents.

There are so many pages of plans, arguments, and comments that if every page of paper was laid on the ground it would stretch 66 miles – the equivalent of a trip from Gravesend to Cambridge.

More than a decade on from when the project was suggested, no physical work has been completed. In comparison, the cost is more than Norway spent on completing a 15.2-mile road tunnel in 2000.

The Scandinavian country only splashed out £140m on the world’s longest road tunnel, around £9.2m per mile, connecting Oslo and Bergen.

Sam Richards, founder and campaign director at Britain Remade, who discovered the huge costs, said: “Britain Remade fully backs the plans for the Lower Thames Crossing, but spending £300m just on a planning application is simply astonishing. Unfortunately, this is set to increase further thanks to our dysfunctional planning system.

“For the hundreds of millions of pounds one part of government is paying another part of government for permission to build the Lower Thames Crossing, Norway could build the longest and deepest road tunnels and have change left over.

“The Lower Thames Crossing is symbolic of what is wrong with our planning system. From multiple rounds of consultation to last-minute government delays for no good reason, currently it’s simply far too difficult and takes far too long to get anything built in Britain.

“But it’s not inevitable that in Britain these kinds of infrastructure projects take so long and cost so much. By overhauling our outdated planning system we can get spades in the ground faster, unlock growth, and create jobs up and down the country.”

Some campaigners however aren’t happy with the costs or the project. Thames Crossing Action Group doesn’t think the new tunnel will ease congestion at the crossing.

Chairman Laura Blake said: “What is being proposed with the LTC is simply not going to solve the problems that we all suffer with due to the Dartford Crossing. It is clear that National Highways still intends to close one of the tunnels when they close the QE2 Bridge, even if the proposed LTC goes ahead.

“It wouldn’t just be when the QE2 Bridge is closed, it would be any time there was an incident at either crossing. It is quite clear that there would not be adequate connections. It would just be more congestion, more pollution, and more chaos.

“Not only that but also the Dartford Crossing would still be over design capacity, even if the LTC goes ahead, and independent assessment of official National Highways traffic modelling has also concluded that the Dartford Crossing would be back to today’s levels of traffic within five years of opening.

“Put simply the proposed £10bn+ LTC would be hugely destructive and harmful, and is simply not fit for purpose. We need and deserve better, and there are better, more sustainable, more affordable alternatives."

Mark Bottomley, Lower Thames Crossing Development director, said: “The Lower Thames Crossing will provide a vital new transport route to help grow the UK economy and improve the journeys of millions of people every year by tackling congestion on the Dartford Crossing.

“We understand that for many the new road is needed urgently and the length of time which goes into the planning can be frustrating. However, it is vital that a project of the size and complexity of the Lower Thames Crossing goes through a rigorous, democratic planning process that makes sure we take every opportunity to maximise the benefits and reduce the impact on local communities and the environment.

“The planning process and our comprehensive programme of consultation and engagement has ensured the views of local communities and stakeholders have been incorporated into our design and we’ve made improvements such as placing 80% of the road below ground level, replanning our works to take thousands of lorries off the roads during construction and amending our plans to enable the Thames Freeport to be developed. The detailed examination of the project finished in December, and the government's team of independent planning experts are currently writing their recommendation so the government can make a decision this summer.”

Meanwhile, in the coming weeks there are a number of community drop-in events where people can have their say and ask questions about the project.

The first is at Bluewater’s Moon Court on Tuesday, February 13, from 10am until 8.30pm. A second is being held at Hempstead Valley Shopping centre, outside Marks and Spencer, on Thursday, February 15 from 10am to 6.30pm.

On Friday, February 16, National Highways staff will be on the centre concourse at Orchards Shopping Centre in Dartford High Street between 10am and 5pm. While on Saturday, February 17, they will be Thamesgate Shopping Centre outside Superdrug at the same time.

Two drop-ins will be held between 3pm on Tuesday, March 5, at Chalk Parish Hall, and Wednesday, March 6, at Cascades Leisure Centre in Gravesend.