The FTA has expressed "utter dismay" at the Welsh Assembly's decision to scrap proposals for an M4 relief road.
Jo Tanner, director of communications at the FTA, says the government in Wales has performed a "complete about face" over the road between Magor and Castleton in Gwent, which had been due to open in 2013.
Ieuan Wyn Jones, deputy first minister and minister for economy and transport, told a meeting of the Welsh Assembly that an estimated tripling in costs - from £340m to about £1bn - was a factor behind the move.
The Welsh government has also dropped plans to improve road access at Cardiff Airport. Tanner adds: "We have seen a complete about face from the Welsh Assembly government, who had promised that the M4 relief road would be open by 2013.
"Without it the future of the South Wales 
economy is severely hamstrung".
Ian Jarman, environmental and legislation manager at Llanelli, Carmarthenshire-based Owens Road Services says: "Having the M4 relief road now not going ahead has left us wondering what the Welsh Assembly government is actually planning to do to ease congestion around the Coldra and Brynglas tunnels area, as this is probably the most congested road in Wales at peak times of the day".