The Church Village bypass opening in Wales this week triggered a dispute over whether construction costs had increased on the project.

Rhondda Cynon Taf Council (RCT) received Welsh Assembly Government funding to build the £90m road, and Welsh first minister Carwyn Jones praised the council and contractor Costain for completing ‘on time and on budget’.

RCT said the budget at contract award in 2007 was £125m and costs were reduced by £35m through value engineering. However, the Welsh Assembly’s Liberal Democrat opposition compared the £90m with the expected £34.8m cost in 2002, when WAG started funding the scheme.

Lib Dem transport spokesperson Jenny Randerson said: ‘Even taking into account inflation, it’s twice the cost it should have been. It’s clearly misleading to say it’s on time and on budget. Delayed projects always escalate in price. It would be more helpful if the government admitted it.’

Richard George, the Campaign for Better Transport’s roads campaigner, said: ‘Councils are notorious for claiming they can build a road for tuppence, only for the real costs to emerge several years down the line.’ He claimed government should protect road maintenance and other vital services rather than write blank cheques for road schemes.

A WAG spokesman said: ‘When RCT originally applied for funding for this project in 2001, costs were estimated at approximately £34m. Subsequent studies, design and analysis revealed that costs would be higher. Construction price inflation also played a part. We reviewed the scheme and agreed in March 2008 a total WAG contribution of £90m.’

RCT Council leader Russell Roberts said the bypass was Britain’s largest local-authority road scheme during its construction.