Tunnels could be dug between Sheffield and Rotherham to cut congestion on the M1.
Consultants say as much as a third of traffic on junctions 33 and 34 is simply crossing between the two towns – and causing jams in an area vital to Sheffield’s prosperity.
Road tunnels between Tinsley and Brinsworth could be the answer, according to Mike Holmes, of WSP, a consultancy hired by Sheffield City Council.
The firm will also consider whether a new motorway junction is needed, at a cost of about £200m, and widening the last mile of the Parkway to three lanes, for £42m.
The city council is desperate to keep traffic moving in an area set to create thousands of jobs.
But gridlock is already hampering major developments.
A £300m extension at Meadowhall – set to create 1,400 posts – has been put on hold for a third time by Highways England.
Mr Holmes said: “In theory you can fix anything with engineering and tunnels are a solution which doesn’t interfere with the M1.
“The numbers we are looking at suggest there’s a solution, with a number of interventions at a number of locations.”
It is only in the last three years that so many hopes have been pinned on the Lower Don Valley.
But then several huge projects came along at once - and the road network has been found wanting.
Thousands of jobs could be created under plans for a giant new Ikea - opening this summer - the Olympic Legacy Park, an Advanced Manufacturing District and a 48-acre Peel logistics depot at Junction 34.
The motorway through Tinsley is on an embankment, lending itself to tunnelling, Mr Holmes said.
He added: “At the moment, up to 35 per cent of traffic on those motorway junctions are on local journeys. It’s acknowledged at a national level this kind of infrastructure is necessary for economic growth.
“With the right kind of benefits there is no reason why you can’t get funding.”
Public transport, car sharing, cycling and walking were a much cheaper and quicker fix, he added.
WSP will submit a report to the Department for Transport in May next year.
Ikea paid for improvements to Junction 34 roundabouts to gain permission for its new store on Sheffield Road.
Meadowhall owner British Land has yet to reveal what measures it is proposing to combat the extra traffic it would create.
A tram-train project between Sheffield and Rotherham has been delayed and is not set to open until summer next year.
Damien Wilson, of Rotherham Council, said they were committed to Parkway widening but the DfT must agree the scheme was value for money first.