Under a blue tarpaulin at the foot of the protest camp, Simon "Sitting Bull" was having a brief break from tunnel digging. "There are three different types of tunnel that you use in anti-roads protests," he explained, showing off his handiwork. "Opencast, doored and shored, and tight and nasty. This one is tight and nasty."

With his head torch he illuminated about four feet of tunnel, which divided at the end to the left and to the right. "Not going to tell you how much further it goes. Sorry," he added.

Sitting Bull's excavations are part of what fellow protesters describe as "the second battle of Hastings". The protest, which saw two arrests on Monday, aims to halt the construction of the Bexhill-Hastings link road in East Sussex and is part of a wave of protests against the government's road-building programme. The road will be just over three miles long and will cost, according to most estimates, at least £86m.

On Monday around 30 to 40 protesters prevented around a dozen contractors from cutting down trees at two locations. At one site three protesters dangled from a giant oak, while at another, two people were constructing rope walks between trees. The contractors were accompanied by around 30 security guards who are in an uneasy standoff with the protesters – not confronting them or attempting to remove them from the trees, but trying to prevent them from occupying new ground. Police stood well back and did not intervene.

The link road was described last year by the Campaign for Better Transport (CBT) as "the most environmentally harmful and least economically justifiable road scheme currently being proposed in England". Even the Department for Transport thinks the scheme risks being poor value for money.

There is, however, plenty of local support for the road. Amber Rudd, Conservative MP for Hastings and Rye, who is also the chancellor George Osborne's parliamentary private secretary, said it "will be an important part of the regeneration of the town [Hastings], opening up a new area for employment and houses". Dennis Haffenden, a local resident, said people in the area supported the road. "It will ease up the traffic through here, it gets really bad sometimes."

In one of the most deprived parts of the south-east, some argue that any economic investment is a good thing. But protesters believe that the funding – nearly half of which must come from local taxpayers – would be much better invested in public transport, housing infrastructure or other local projects. The county council is "already planning to cut £34m from adult social care and £14m from children's services", said one protester, Abby Nicol.

And the campaign may be just the beginning of a national one. In December, Osborne announced a £1bn national road-building push as part of his autumn statement. In response CBT released a report highlighting 191 road schemes around the country, and held a conference to bring campaigners together and to organise resistance.

"We warned last year that there would be resistance," said CBT road campaigner Siân Berry. "We think we'll see more and more of these protests as the road building schemes get under way."

Back at the site, where the protesters claimed to have dug new tunnels, Indiana watched as the contractors lopped branches off a large oak. "That tree is ancient," she said.

"You need four people to get your arms around it."

Does she think they will be able to stop the road being built? "What you have to understand is that it's not about just one tree, however beautiful it is, or about one road. We want to stop all of Osborne's roads. It's about hundreds of roads and thousands of trees," she said.