I live in a country with many trains – after the Japanese, the Swiss travel the second-most by train and year. Naturally, there are thus more than one company that equip the railway corporations with trains.
However, there is one specific aspect in their design that merits close attention because it shows intelligent — and less intelligent — engineering: The toilet door.
The following image shows the lock mechanism of both kinds of doors. The upper is a very simple, mechanical lock: You open and close the door with a handle and to lock, you simply turn the knob. Instant feedback is given by noise and a big, visual indicator.
The second one is more sophisticated. It’s actually an electrical door that doesn’t require much force to open and close it. Definitely a piece of great engineering, which certainly took a lot of time to develop and implement. With the green button, you give the command to open or close the door and with the red button, you lock or unlock it. But: the noise feedback is missing almost completely and the visual feedback consists of two small LED’s that are either light or dark.
While, after such an explanation, you would most definitely be able to use both doors equally well, it becomes quickly and also embarrassingly obvious that the latter is flawed if you sit in the train: You can observe that almost every time someone that never used that toilet before is going to the loo, you can bet that they push only the “close” but not the “lock” button. With the result that the door’s not really locked.
What generally happens is, that another person will push the “open” button from the outside, creating some silence and embarrassing moments for both parties. Worse, because the door’s operated electrically and at a very low speed, it takes ages to close the door again.
The interesting part of this is, that the technically superior solution with lots of “nice” features is practically challenged by the simple yet always working solution with a door that’s opened by hand and which has a big, round knob to lock it.
So, if you design anything, please keep in mind that still, the simpler solution is maybe the better one …
Update 14.11.2006: Recently, the operator added big blue stickers to the electrical doors, exlplaining how to use the buttons and asking people not to try to pull the door open or close. Yikes. Picture is now part of the “Making Life Easy” group on flickr.