Interrupted daily flow of people going to work đź‘Ť
Make it 10 years custodial
Actually the Dartford Crossing comprises of two tunnels and one bridge. The tunnels take the traffic northwards, and the bridge southwards.
They often close the bridge - windy days, maintenance work, whatever. The tunnels then take traffic both ways.
The real reason that they got the long sentence was the supposed defiance of a court order. The court order stated that they must not protest on the M25 motorway or obstruct it as before. Accordingly they moved to the bridge which is not part of the motorway. Neither did they obstruct the bridge - a decision was taken to close it. Ambulances and other emergency vehicles do not routinely use the bridge since it spans two different counties. The usual system then prevailed, the traffic used the tunnels.
The rights to freedom of expression and the right to protest under articles 10 and 11 of international law which is cemented into UK law through the Human Rights Act.
If you then say that they did not have the right to protest, then equally you have no right to free speech.