Twelve campaigners will face no penalty after staging a protest near Heathrow against airport expansion.
A small group of people ran on to the M4 and A4 roads, and lay down in front of oncoming traffic, causing a temporary disruption on Saturday November 19.
Fifteen people aged between 21 and 67 were charged with wilful obstruction of the highway.
At a hearing at Ealing Magistrates' Court, 12 of them pleaded guilty and were given a conditional discharge.
They were told they would each have to pay a victim surcharge and prosecution costs of £105.
The court heard their motivations were fears about air pollution potentially caused by a third runway at Heathrow, the urgency of climate change and social inequality.
District Judge Stephen Day gave the 12 defendants a conditional discharge, pointing out that they had pleaded guilty at the first opportunity, and that they were all of good character and had no previous convictions.
Prosecutor Richard Doolan said the protesters were joined together by plastic tubing and some of the defendants had to be cut free.
They were removed from the road in less than half an hour, he said.
The court heard that police knew a protest had been organised.
Those sentenced after pleading guilty were Madeleine Ellis-Petersen, 24, of Ealing; Joanne Louise Bodimeade, 28, of Lambeth; Alexis Delage, 25, of Lewisham; Tom Venner-Woodcock, 29, of Southwark, and Tess Lotter, 30, of Camden, all in London.
Also sentenced were Antoine Thalmann, 25, and Henry Owen, 23, both of Oxford; Simon Bramwell, 44, of Stroud, Gloucestershire; Ian Bray, 49, of Kirklees, West Yorkshire; Graham Lewis, 53, of Wells, Somerset; Thomas Harford, 26, of Bristol, and Sibi Moore, 21, of Sidmouth, Devon.
Lewis wore a white shirt in court which said: "Plane crazy runway hell."
He also intervened at one point in proceedings to say he was a "trainee Buddha".
Speaking after the sentencing, Ellis-Petersen said: "It's a great result within the realms of what we were expecting."
She added: "This is not the end. We will continue to fight until the Government takes meaningful action to tackle climate change and that includes not building a third runway."
Asked if she would stage a similar protest again, she said: "If that's what it takes."
The court heard the defendants are involved in voluntary work with charities and in the community.
Earlier, Isabelle Anderson, 30, of Hebden Bridge, and Sophia Lysaczanko, 28, of Haringey, pleaded not guilty to wilful obstruction.
Anderson will go on trial on February 6 at Uxbridge Magistrates' Court, and Lysaczanko will go on trial at the same court on February 7.
Margaret Charnley, 67, of Bristol, was not at the hearing as she was excused from attending but a lawyer indicated a plea of not guilty.