The cost of changes to the route of the Norwich Western Link will fall on the county council, rather than its contractors, leaders have confirmed.
Norfolk County Council officers need to devise an alternative route for part of the northern section of the £198m road, after surveys confirmed protected barbastelle bats roosts nearby.
The council says full details of how the scheme could have to change and any impact on cost will not be clear until June.
But, following a question from Labour group deputy leader Emma Corlett at Monday's cabinet meeting, it was confirmed any extra costs would fall on the council, rather than on contractor Ferrovial.
Martin Wilby, cabinet member for highways, infrastructure and transport, said: "The latest alignment refinement is part of the design process and has been instructed by the council. Therefore, the cost of this work rests with the council under the terms of the contract, as it is a change to the original contract proposals."
Supporters say the scheme, to link the A1067 Fakenham Road to the A47 west of Norwich, will cut rat-running and bring an economic boost, although critics say it will damage habitats and increase car use.
The Conservative-controlled authority is waiting to hear if the Department for Transport (DfT) will approve its business case for the road - and contribute £168m towards it.
Mr Wilby also faced questions about a letter councils got from the DfT, stating: "It is likely that we will not have sufficient funding to continue to fund all the schemes currently in the programme to the current scale or timing."
The letter asked councils and regional transport bodies to review priorities.
Ben Price, leader of the Green group, asked: "How is Norfolk County Council preparing for the likely eventuality that the DfT will not fully fund the Western Link?"
Mr Wilby said the council was working with Transport East - made up of local councils, Local Enterprise Partnerships and businesses across Norfolk, Suffolk and Essex - over its response.
But he said: "There is currently no reason to believe that the support for the Western Link to remain part of their recommended projects, alongside other important infrastructure projects within Norfolk, has changed."
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