Costs have soared for a major scheme to improve Derby's road system.
The Connecting Derby project was originally expected to cost about �23m but project leaders predict it will rise to more than �38m.
The government, which is providing the bulk of the cash for the initiative, has agreed to pump in a further �9m.
But the city council is now set to have to contribute �7m to ensure it can be completed. The project includes finishing an inner ring road.
The scheme, which is already under way, will see new junctions, new roads, changes in the direction of traffic flow and additional pedestrian priority.
The additional council funding is set to be agreed by its cabinet on 14 June.