Workmen trying to cut trees down along a railway were stopped dead in their tracks.
The contractors moved on after the protests
The men were confronted by protestors who say the felling, in the Montpelier and St Werburghs areas of Bristol, is unnecessary and should stop.
Network Rail says the work must go on because it is the only way to cure an age-old problem - leaves on the line, which causes the trains to skid dangerously on the tracks.
On Wednesday morning, many protestors were willing to trespass on the railway lines to make their point, prompting the contractors to move further down the line.
One protestor said: "It's all that we have in the city and it's being taken out for no reason that I understand at all.
"My daughter and I walked up here yesterday and when we saw it, we were utterly horrified and devastated at what they had done."
Another added: "They are cutting trees down that are 30 or 40 ft down the bank and they're saying it's for safety, but trees don't fall uphill."
"I feel sad. I have watched these trees grow from saplings, these people may own the land by they are answerable to us all."
Despite the protests, a spokesman for Network Rail said the work would continue - so trains were not delayed and passenger safety was ensured.