Hundreds of commuters wore cattle masks as they boarded their trains in an angry protest against unreliable services and rising fares.
Campaigners gathered at 20 stations across the South West and handed out "fake tickets" for passengers to display their displeasure at the service provided by First Great Western.
There was standing room only on the Bath Spa to Bristol Temple Meads service after 40 passengers brandishing the special tickets were allowed through barriers.
Peter Andrews, one of the leaders of the More Train Less Strain group, said: "We feel at last our message is beginning to get through. The First Great Western service is appalling. Have a look around, no one can sit down."
Mr Andrews said First Great Western's fares were now the most expensive in Europe and he hoped special tickets sent to Transport Secretary Ruth Kelly would prompt the Government to intervene. He said: "The sight of all these passengers in their cattle masks could not paint a clearer picture of the public's disapproval of the service."
First Great Western insisted most of the passengers allowed through with fake vouchers had already bought tickets.
Spokesman Adrian Ruck said: "On trains and stations across the network fewer than 100 people refused to pay, out of 100,000 passengers and 1,350 services.
"We have taken the names and addresses of this tiny percentage of customers - this is the usual policy for fare evaders.
"We accept that the service has fallen short in the past and we will continue to have dialogue with the public to resolve these issues."
Comedian Dom Joly boarded a train to support the campaign.
