Hauliers say that a decision to ban heavy goods vehicles from the M48 Severn Bridge could be "devastating" for their businesses.
The ban will come into force for at least 18 months from 27 May after National Highways discovered the cables supporting the structure are deteriorating.
A director of an Avonmouth-based haulage company warned the alternative route into Wales via the M4 Prince of Wales Bridge is not always reliable, and drivers could be forced to take lengthy detours around Gloucester.
National Highways said it has "no choice" but to impose weight limits in the interest of public safety, and that it was looking for a long-term solution to allow HGVs to return "in a controlled manner".
It is currently proposing a "technological solution" that will manage the flow of HGVs over the bridge to prevent overloading it.
