Signal Systems & Communication Flashcards
7 cards from real REC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Signal Systems & Communication flashcards as text
What does 'signal indication' refer to in railroad operations?
Answer: The required engineer action or speed limit conveyed by a signal aspect
Signal indication is the meaning conveyed by a signal aspect—what action the engineer is required to take in response to what they see.
What is 'tumble-down' logic in a signal system?
Answer: The automatic propagation of restrictive indications from one signal back to preceding signals
Tumble-down logic causes a restrictive condition to automatically propagate backward through preceding signals, warning approaching trains of a stop indication ahead.
During a radio failure in CTC territory, how should an engineer proceed if no signals are displaying a clear indication?
Answer: Stop and protect the train; wait for dispatcher contact by other means
A combined radio failure and restrictive or absent signals requires the engineer to stop and protect the train, then contact the dispatcher using any available alternate means.
What does 'TWC' (Track Warrant Control) allow when there is no wayside signal system?
Answer: Dispatchers to grant and restrict train movements verbally or via data link
Track Warrant Control is a method where dispatchers issue warrants that authorize specific train movements over defined limits in dark or non-signaled territory.
What is the significance of a 'distant signal' located ahead of a home signal?
Answer: It provides advance warning of the home signal's indication, allowing time to adjust speed
A distant signal is placed far enough in advance of the home signal to give the engineer sufficient distance to react and adjust train speed before reaching the home signal.
Under PTC requirements, what event must be reported to the railroad's designated officer when a PTC system malfunctions?
Answer: It must be reported immediately so a conditional authority or alternate method can be established
A PTC malfunction must be immediately reported so that the railroad can authorize the train to continue under an approved alternative movement authority procedure.
What is 'restricted speed' on a railroad, and what must the engineer be prepared to do?
Answer: A speed not exceeding 15 mph, prepared to stop within half the range of vision
Restricted speed means proceeding at a speed not exceeding 15 mph and being prepared to stop within half the range of vision ahead.