Bristol MetroBus scheme cost up by further £4.6m
The cost of building Bristol's MetroBus network has risen a further £4.6m, the council has admitted.
The bill for the North Fringe to Hengrove route has gone up to £117.9m since November, a report indicated.
Drivers in the city have faced months of delays caused by work on the network across Bristol.
South Gloucestershire Council blamed a series of construction delays for the extra costs.
The £216m MetroBus network aims to provide better public transport and cycling infrastructure across Bristol.
Campaigners said they were "not surprised" the costs had spiralled.
The report to cabinet said the scheme has "faced a number of issues during the delivery phase, which have now resulted in an estimated forecast outturn cost of £117.9m, an increase of £4.6m over the November 2016."
The bill for this section of the network is now £16m higher than forecast two years ago.
The South Gloucestershire authority will need to spend an extra £9.8m above its original £30.5m contribution to the scheme, to cover the increased costs.
It is recommending the extra is taken from the highways maintenance budget over the next 10 years.
Its senior environmental policy officer Jane Antrobus, said in the report: "Failure to support the extra funding needed for completion of this project would put these benefits at risk."
Commuters have been enduring roadworks associated with the scheme in the city centre, on the M32 and various other locations in South Gloucestershire.
In October, the mayor of Bristol said he would investigate complaints about a busy commuter route that was made one-way for the North Fringe-to-Hengrove construction.
Amanda Vinall, from the Stoke Lane Action Group, said costs had soared because multiple contractors had been hired.
"It's crackers and lessons have to be learned," she said.