Bosses said “short-term and piecemeal planning” may be undermining plans to build a new road link and tunnel between Kent and Essex.

At the final event before the consultation closes this week, business leaders expressed their concerns that proposals for a Lower Thames Crossing do not include improvements to important parts of Kent’s road network.

Consultants working on behalf of Highways England tried to reassure more than 100 people at the Great Danes Hotel in Maidstone that the scheme would not cause congestion elsewhere in the county.

However, they said the scheme was unlikely to be approved if it tried to solve the county’s entire traffic problems.

Their brief is to alleviate congestion at Dartford, which is why proposals to the east of Gravesend, known as Option C, had been chosen.

Andrew Stupple, marketing representative at Canterbury-based Academy for Distance Learning, said: “I think there’s merit in the idea for a Lower Thames Crossing but they are more interested in getting the funding from Government than making sure they build the road links to get to it.

“The whole thing should be done in unison. It seems to me like they have a fragmented road policy.”

At the consultation event on Friday, businesses said upgrades were needed to the junctions at both the A229 and A249 linking the M2 and M20.

They also raised concerns the tunnel is only set to be two lanes wide, with the potential to extend capacity to three lanes.

Douglas Horner, a director at construction firm Trenport Investments, which has developments across Kent, said: “I’m concerned with the short-term and piecemeal planning.

“Will the tunnel be at capacity on the date it opens? If not, how soon will it be required to exceed capacity?

“We are putting in the provision to build a three-lane tunnel. Would it not be wiser to build that now? This is part of the transeuropean network. It has international significance. This piecemeal approach to improvement is not adequate.”

Peter Fry, a senior consultant at CJ Associates, which is working on the project for Highways England, said: “We don’t just look at the problems in Dartford in isolation but these projects are a balancing act.

“We have defined parametres we have to work in. You can’t pile too much stuff on a project because it becomes unaffordable. Then the business case gets dicey.”

Jo James, chief executive of Kent Invicta Chamber of Commerce, said her organisation had responded to the consultation in favour of Option C.

Mrs James, who is also a board member of South East Local Enterprise Partnership, which organised the meeting, said: “This is a once in a generation opportunity to create new development, new jobs and stimulate much-needed investment.”

The consultation closes at 11.45am on Thursday, March 24. Details at www.lower-thames-crossing.co.uk