There aren't any. This means that people think a train is full if you can't get on without touching someone. If a lift/elevator has a capacity of 14 posted, nobody gets in if there's more than six on board. "it's too full, i'll wait for the next one" Waterloo Station has a maximum of maybe 12 trains and 20 buses an hour and is correctly called one of the busiest stations in the country. Quick, send these people to London or New York. Or even Liverpool or Baltimore.