Post by Jefferson Lee Eng
Actually, it's a push button, but except for the Villanova, Bryn Mawr,
and terminal stops, passengers that want to board the next scheduled
Rt 100 at an intermediate stop have to push the button to signal to
the driver operator that a stop is required.
As Jefferson said, they're pushbuttons now (replaced the cords c. 1980).
For those who are interested, the way that the signals drop when a train
stops at the station, but don't drop when an express comes through is as
There is a fourth rail at the flag stop stations, under the platform where
the third rail shoe would contact it. That's connected to a time-delay
relay, or something like that. When a train is at the station, current
flows from the third rail to the shoes on that side to the shoes on the
opposite side to the fourth rail. If the current stays on long enough (as
in a train stopping, or proceeding through slowly, which is what operators
did when the signal was set and no passengers were visible), the signal
goes off. If an express comes through, it doesn't shunt the fourth rail
long enough to drop the relay, so it stays on.