Proposed improvements to a busy motorway junction have been criticised by local firms.
Under the plans M1 southbound drivers would not be able to join the M6 at the Catthorpe Interchange, the Coventry and Warwickshire Chamber of Commerce said.
A14 motorists would also not be allowed south at the junction, it added.
The M1, M6 and A14 meet close to the Warwickshire/Leicestershire border. The Highways Agency said the scheme chosen was the most popular with the public.
It said the changes would remove direct access to the motorway network from the local roads and new local routes would improve travel between villages.
The agency said there would be direct links from the A14 to the M1 northbound, the M1 southbound to the A14, the M6 to the A14 in both directions, the M6 to the M1 southbound and the M1 northbound to the M6.
Simon Leech, chairman of the Rugby branch of the chamber, said about £400m would be spent on a junction "that has two glaring errors".
He said: "If you're going to spend that much money, surely it should be a once-and-for-all fix.
"If we want to encourage [major companies] to grow and other companies to come to Rugby, if they see there are logistical problems, they may locate somewhere else."
A Highways Agency spokesperson said: "The current layout suffers from serious congestion, leading to major delays for motorway and trunk road users.
"There is an accident problem around the junction and travel between villages is difficult for local traffic and pedestrians. The improvements will tackle all these issues."
Subject to funding and planning issues, work at the junction is expected to start in the summer of 2011, the agency said.