Two Devon councils are considering borrowing more than £23m between them to help fund a south Devon bypass.
The South Devon Link Road bypass between Newton Abbot and Torquay was first proposed more than 50 years ago.
A recent costing estimated the scheme's budget at £110m, of which the government is willing to fund £76.3m.
Torbay Council and Devon County Council had approved giving £10m between them to help fund it. They are to discuss plans for more borrowing next week.
The Department for Transport had been willing to provide more than £100m for the project, but that was cut because of government savings.
Those in favour claim it is vital to the economy of south Devon and it will also reduce congestion, improve air quality and improve road safety.
But opponents claim it would damage the village of Kingskerswell by stopping traffic travelling through it and disrupt the ecology of the surrounding countryside.
Both councils had agreed to provide about £5m towards the project.
Devon now needs to provide another £11.7m and Torbay another £11.5m.
In a report going before Torbay Council which the BBC has seen, officers explained that the total debt, including the new £11m, was likely to cost council tax payers about £1.2m a year to pay off.
'Best single investment'
The council said the debt was be manageable and that it was a price that had to be paid.
Conservative elected mayor Gordon Oliver said: "It is the best single investment that we can make for Torbay.
"We're were the only conurbation [urban area] in the whole of the UK that isn't connected to the motorway network."
Opponents of the scheme said it was not a good use of public money in a time of austerity.
Ken Pegden, from the Kingskerswell Alliance, said: "We see the need to make savings by both councils and I don't believe that it is right that cuts that should to be made to vital front-line services to fund a road that is not necessary."