Protestors at the dualling of the A5 road from Aughnacloy to Londonderry have set up camp along the route.
Transport Minister Conor Murphy identified the preferred route for the new A5 last July.
The new road will be an 86km long dual carriageway and is estimated to cost between £650m and £850m.
The road could lessen journey times by up to 20 minutes, but campaigners said the environmental impact far outweighed the shorten journey time.
Local protestors and campaigners from Climate Camp, a group of environmental activists who travel around Britain and Ireland, are camping in the field of a farmer outside Victoria Bridge.
The new route would cut across his land.
Molly Walsh from Climate Camp said they expected up a couple of hundred people to join in their protest over the weekend.
"More roads mean more cars and more cars mean more pollution," she said.
"Climate change is one of the greatest threats that is facing us right now, a much greater threat than traffic congestion.
"We're proposing the rail link be put back.
"I'm from Donegal, but I live and work in Dublin so I use the A5 quite a lot. But I'd much rather get on a train in Dublin and off in Derry without having to go to Belfast and all the way around the north Antrim coast."
Marcus Isherwood from Omagh Chamber of Commerce said the road was needed because the area had been "deprived of much needed inward investment".
"From an economic prospective the A5 is a crucial piece of infrastructure that must go ahead," he said.
"If you look at what inward investment companies put on their wish list it's road networks, airports, seaports, telecommunications.
"Infrastructure lets us down so it is crucially important."
The plans for the new route will be put out to public consultation in 2011.
Construction of the dual carriageway is expected to commence in 2012 and be completed in 2015.