Steve Dulieu wrote:

Most (all?) of the ones on the Munich S/U-Bahn seem to work on a "who
steps on the actuator plate first" system. As you approach your
stopped escalator (with an illuminated sign showing two arrows
pointing up and down) and step onto the flat plate at the start, the
escalator bursts into life, the double arrow light at the start end
changes to a single arrow pointing in the direction of travel and the
double arrow at the terminus end changes to a "No Entry" type
roundel. The escalator keeps going for as long as people keep
stepping on the actuator plate, then after it has moved sufficient
distance to transport the last person to step on the actuator to the
other end, it runs for about another 5 seconds then stops and goes
back into "first-come" mode. Of course, for the impartial observer,
this provides for some most amusing spectating of "can I get to the
actuator before that bugger coming the other way" type racing.

So if two people approach two escalators from the top, both escalators start
running down, and then a trainfull of people arrive at the bottom with no up
escalator for them?