They fear that more than 20 separate road schemes along the 230 mile route are slowly and stealthily turning it into a fast coastal "superhighway". At present only one quarter of it is dual carriageway.
Their chain of bonfires mimicked the beacons lit more than 500 years ago to warn of the arrival of the Spanish Armada.
"We chose Friday the 13th because it's one of those days when nasty things happen," said John Stewart of the national anti-roads group Alarm UK and one of the organisers.
Most of the individual schemes along the Folkestone to Honiton trunk road are by-passes. The road widening and straightening schemes in the open countryside are justified by the Department of Transport as improvements needed to cope with existing trafficbottlenecks. But protesters say this conceals the big picture - the linked schemes will produce cross-country stretches of fast dual carriageway.
Several of the schemes along the A259, the A27, the M27, the A31 and the A35 via Hastings, Brighton, Southampton and Dorchester, will damage Government-designated wildlife sites or Areas of Outstanding Natural Beauty, including the South and North Downs.
Roads and rail Minister John Watts said yesterday: "The suggestion that this route is being improved by stealth is a nonsense." .Reuse content