The Docklands Light Railway in East London is a modern marvel. Trains stop at the same place, to an inch, on the platforms. Hence, passengers have learnt where to stand to gain access to the trains. Hence, when the doors open, passengers trying to get off are met with a plug of people, blocking the exit. Then, as you try to get on, some of the wedge of people don't move. Why? Well they are waiting for a later train, to a different destination. But they want to maintain their position in the "queue".
Fritz Laing's Metropolis (1927) has been realised in 2007. Man and machine, man becomes machine, and we all line up!
DLR is driven by machines. Computers on the train and computers in the central control. The doors are shut by "Train Captains", who have little regard for late running passengers. At Bank station, where trains start their journey, there are often heated words when the doors at shut in people's faces. The staff say "we have to maintain the timetable". Odd that. I have often seen DLR staff hold doors open when it suits them...
DLR is part of Transport for London. As such, it can accept Oystercards as a means of payment for travel. "Oystercard Pre pay" (also know as "pay as you go") and Travelcards can both exist an an Oystercard's ARPHID to be read by men and machines. But the DLR is an open platform system, so you have to remember to "touch in and touch out". Great. Just don't forget!
And aren't all tickets "pre pay"?
But if you go to a DLR start a journey, travel to a destination, and come back within two hours you may find yourself with a penalty fare, since the "touch out" at the destination is a registered as a "touch in", and hence you outward journey is not complete. Hence incomplete. Hence a fine, or a "full cash fare" deduction from your card.