A new umbrella organisation has been set up to coordinate anti-road protests across Britain.
Road Block has warned direct action may become common
Campaigners behind Road Block say they have formed the group because of proposals to build new motorways or widen existing ones.
The group aims to highlight "the insanity of more road building" and to support sustainable transport options.
It has warned that direct action to try to stop roads - seen in the 1990s - could become common again.
On Monday, Road Block campaigners met to try to stop work on a £50m bypass from Stoke Hammond in Buckinghamshire to Linslade in Bedfordshire.
Local residents claim the road is being built for huge housing developments and expansion at Luton Airport.
More than 50 families with children and others started arriving at 0630 GMT but no contractors turned up to start work.
In the mid-1990s hundreds of environmental protesters locked themselves to trees, buried themselves in tunnels and sat in front of bulldozers to stop a bypass in Newbury.
The bypass went ahead, but was delayed by the protest campaign.
Stephen Joseph, director of campaign group Transport 2000, said: "Unless destructive road building becomes firmly a thing of the past, we will see the re-emergence of mass protests, last seen at Newbury and Twyford Down in the mid-90s."
BBC transport correspondent Tom Symonds says campaigners believe a series of road improvements proposed by the Government could become new flashpoints for direct action.
"But with road congestion growing, the Government believes it has bent over backwards to make sensitive decisions about roads building," he says.
Road Block says road building is environmentally unfriendly, divides communities and contributes to health problems.