Roadchef raises objection to proposed M4 relief road
A motorway services operator has lodged an official objection to the proposed route of the £1bn M4 relief road.
Roadchef, backed by hauliers, said the so-called black route would be "devastating" for its Magor services in Monmouthshire, which employs 190 people.
It follows an official objection by the owners of Newport docks in April.
However, the CBI said most businesses were telling the Welsh Government to "get on with it".
David Cameron urged the re-elected Labour administration in Cardiff Bay to take immediate action to tackle M4 congestion.
During Prime Minister's Questions, he told MPs: "It's a vital transport artery - we've given the Welsh Government £500m in increased borrowing powers.
"The delay in upgrading the M4 is damaging business in south Wales and frankly it's high time the Welsh Government got on with it."
The proposals - first put forward 25 years ago - are for a 15-mile (24km) motorway and six-lane bridge over the River Usk to ease problems from the bottleneck at the Brynglas tunnels.
Roadchef has hired a QC to challenge the plans, which it said would leave the site under threat of closure as it would mean drivers taking a detour of about four miles (6.4km) to use the facilities.
The company has been supported by the Road Haulage Association and the Freight Transport Association.
There are question marks over the future of the M4 plan, with Labour failing to get a majority in Thursday's Welsh Assembly election and Plaid Cymru, the Liberal Democrats and UKIP all against the black route.
The Welsh Conservatives support building an M4 relief road but have not settled on an option. The group has not previously done deals with Labour on budget negotiations.
Roadchef estimates the current plan could trigger an 80% drop in long-haul traffic at Magor and leave a "dangerous" gap of almost 50 miles (80km), as the M4 black route has no provisions for a new service station.
As a result, the company has put on hold £1.7m of new investment.
Simon Turl, chief executive of Roadchef, said: "Our submission assesses that the planned route has serious implications on safety grounds, is inadequate for road users, will threaten the future viability of our site and our 190 employees and will increase carbon emissions."
Other businesses have raised objections.
But supporters of the M4 black route have suggested some firms may be exaggerating the potential damage to their businesses in order to improve potential compensation claims if it gets the go-ahead.
Roadchef denied that was its motivation, saying it wanted to avoid compensation altogether by finding a solution, such as a repositioning of a junction.
However, CBI's director general Carolyn Fairbairn said moving ahead with the black route, the previous Labour government's preferred option, should be a priority for the next administration.
"Businesses are very concerned for this decision to be taken. They feel it was part of the plan and it now needs to be reconfirmed. This is about real costs and the competitiveness of the Welsh economy," she told BBC Wales during a visit to south Wales.