Two brickies in a white van became the first motorists to drive along Angmering's new £4 million bypass.
Scores of people waved and cheered as the van, with the two builders inside, passed beneath a footbridge over the two-mile dual carriageway.
Developers building hundreds of homes at Bramley Green in Angmering paid for the road, which was completed four months ahead of schedule.
Residents hope heavy lorries will now stop using the village as a short cut from the A27 to the A259.
West Sussex county councillor Tex Pemberton, who has special responsibility for transport planning, cut a red ribbon to open the bypass.
He told villagers: "It must be as if you have won the lottery.
"It will take a little while to settle down but it will bring welcome relief to Angmering village centre.
"It will allow us to introduce some traffic calming in Angmering, which will enhance the village environment."
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