emergency power system

[rail10]

in nyc subway system what types of emergency system and alarms are in place in case of a power failure,accident or other causes and how it differs from the emergency power system used in the newer computerized washington subway system?

[F40]

Not sure about inside the stations, but if a train loses power en route (3rd rail shuts off), that will cause the train to trip.

[Allan]

Not sure about inside the stations, but if a train loses power en route (3rd rail shuts off), that will cause the train to trip.

Actually, no. If the 3rd rail (DC current) loses power the train will continue to roll with forward momentum until it comes to a stop or the T/O applies the brakes using whatever air is in the reservoir. This is very useful if a train is near a station when power is lost thus preventing it being stuck in the tunnel.

If the train trips it is because the nearest signals trip/stop arm is up which would happen if power (AC current) is lost to the signals as well. If signal power is still on then the train can continue to roll as described above.

[arrow]

Allan is right. If the train loses power for whatever reason, the train is allowed to coast to the next station.

[F40]

Not sure about inside the stations, but if a train loses power en route (3rd rail shuts off), that will cause the train to trip.

Actually, no. If the 3rd rail (DC current) loses power the train will continue to roll with forward momentum until it comes to a stop or the T/O applies the brakes using whatever air is in the reservoir. This is very useful if a train is near a station when power is lost thus preventing it being stuck in the tunnel.

If the train trips it is because the nearest signals trip/stop arm is up which would happen if power (AC current) is lost to the signals as well. If signal power is still on then the train can continue to roll as described above.

Thanks for the clarification. It is another reason why I do not venture onto SubChat anymore. You never know when an extraneous 'fact' goes around unnoticed.

Years ago when I didn't know any better and stuck with SubTalk (formerly), someone mentioned the 'blue lights' in the tunnels are either call boxes or places where the 3rd rail can be switched off. Which is true?

[Allan]

Not sure about inside the stations, but if a train loses power en route (3rd rail shuts off), that will cause the train to trip.

Actually, no. If the 3rd rail (DC current) loses power the train will continue to roll with forward momentum until it comes to a stop or the T/O applies the brakes using whatever air is in the reservoir. This is very useful if a train is near a station when power is lost thus preventing it being stuck in the tunnel.

If the train trips it is because the nearest signals trip/stop arm is up which would happen if power (AC current) is lost to the signals as well. If signal power is still on then the train can continue to roll as described above.

Thanks for the clarification. It is another reason why I do not venture onto SubChat anymore. You never know when an extraneous 'fact' goes around unnoticed.

Years ago when I didn't know any better and stuck with SubTalk (formerly), someone mentioned the 'blue lights' in the tunnels are either call boxes or places where the 3rd rail can be switched off. Which is true?

It can be either one or both.

[F40]

Score one out of too many.