Protesters have pledged to keep up their guard in case a controversial road scheme is revived.
Campaigners said a protest camp in woods at Tortington Common, near Arundel, would stay in place to make sure plans to build a bypass were not resurrected.
Transport Secretary Alistair Darling axed the controversial scheme, along with others on the fringes of the South Downs, last week.
Pressure group South Coast Against Roadbuilding said it was taken by surprise by the decision but could not rule out a U-turn.
Spokesman Ian Brookes said: "The protesters' camp at Tortington Common will stay. For all we know there may be a different government in two years time with a policy of building an M27 through the ancient woods and across the Downs."
He said there was now an opportunity for campaigners and councils to work together to reduce traffic.
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