One of Dublin Port's biggest container companies is considering taking legal action against Dublin City Council on the basis that it would be "put at a competitive disadvantage" if its trucks were forced to use the port tunnel.
Marine Terminals Ltd (MTL), which is located in the south port container terminal, said the trucks would have to pay €4.80 each way in tolls to cross the East Link Bridge and, with 150,000 truck movements a year, this would amount to €7.2 million.
The company's general manager, Éamon Sullivan, said it was "considering all options, including closure" if the city council proceeded to implement its strategy of excluding trucks from the city centre from 7am to 7pm when the port tunnel opens later this year.
MTL employs 100 people, and Mr Sullivan said a further 1,000 people "depend on us for their livelihood".
Other options being examined by its solicitors, Arthur Cox and Company, include seeking an injunction or judicial review of the council's decision.
"At the moment, truck drivers have a choice - they can go over East Link, down the canal, along Pearse Street or anywhere they like. Our difficulty is with a toll being placed in the middle of the port when they have no alternative but to use the East Link."
Mr Sullivan said MTL had "no issue" with the purpose of the port tunnel to take heavy goods vehicles (HGVs) off the city streets - even though many of its drivers would have to travel all the way round the M50 and through the tunnel to get to the south port area.
Some 300 trucks would be added to the East Link during the morning and evening peak periods as a result of this diversion "and that's going to be a nightmare, particularly for car users", he said. Freight companies in the north port would not be so affected.
"We will do everything we can to protect ourselves", Mr Sullivan said, adding that another option being considered was to take its case to the Competition Authority on the basis that the city council itself is a shareholder in the East Link with National Toll Roads.
Reg McCabe, transport director of Ibec, which also has serious reservations about the HGV management strategy, said its implications "only came into focus before Christmas" when the council produced its map showing the extent of the truck exclusion zone.