"The Welsh Government has failed to make a business case for the proposed Northern Access Road to the Enterprise Zone in St Athan," said South Wales Central regional AM Andrew RT Davies.
Calling on ministers to scrap the plans, the Welsh Tory leader referred to several questions he had asked in the Assembly over the past few weeks, saying they had failed to counter suggestions that upgrading the existing road infrastructure would be sufficient.
The road is set to cost £15 million, but Mr Davies has called for that money to be put towards other infrastructure projects in the Vale.
Over 100 people attended a public meeting in Llanmaes last week and in a show of hands, all present voted against the road.
Unlike the proposed road, the Dinas Powys by-pass has widespread local support, with many people believing it will solve congestion problems between Cardiff and Barry in the eastern Vale.
Mr Davies said he has written to cabinet secretary for economy and infrastructure, Ken Skates AM, asking him to scrap plans for the Northern Access Road and instead put the money towards delivering the by-pass.
He went on: “I have raised concerns about the lack of a business case for the Northern Access Road on several occasions and, sadly, Welsh Government Ministers have failed to make it. There is widespread local opposition, with many people feeling the road is unnecessary.
“With no evidence to the contrary, the logical step is for us to upgrade the existing road infrastructure and that way we can all get on with making the St Athan Enterprise Zone the success we want it to be.
“I have, therefore, called on the Cabinet Secretary to scrap plans for the Northern Access Road and put the money towards the Dinas Powys by-pass instead.
“We have a situation where residents in one part of the Vale are vehemently opposed to a new road, while in another part, residents are campaigning hard in support of one.
“It seems illogical not to put the money towards a project people want, as opposed to one that has been the source of many local concerns.”