REC Signal Systems & Communication 3 — Questions and Answers
Question 1: What is 'approach locking' in signal system terminology?
- A lock preventing signal changes while a train approaches and occupies the block (Correct answer)
- A mechanical lock on switch points
- A cab signal that locks at the last indication
- A dispatcher lock on track warrants
Correct answer: A lock preventing signal changes while a train approaches and occupies the block
Approach locking prevents a signal from being cleared or a route from being changed after a train has approached within a specific distance of that signal.
Question 2: Under Centralized Traffic Control (CTC), who has authority to align switches and signals?
- The locomotive engineer
- The conductor
- The train dispatcher at the control center (Correct answer)
- The signal maintainer on duty
Correct answer: The train dispatcher at the control center
In a CTC territory, the train dispatcher remotely controls all switch and signal alignments from a centralized control center.
Question 3: What does the term 'vital' mean when describing a railroad signal circuit?
- The circuit is energized at all times
- A failure of the circuit results in the most restrictive indication (Correct answer)
- The circuit controls life-safety equipment only
- The circuit is monitored 24/7 by dispatchers
Correct answer: A failure of the circuit results in the most restrictive indication
A vital circuit is designed so that any component failure causes the system to default to the safest (most restrictive) state.
Question 4: In a cab signaling system, where is the signal indication displayed?
- On a pole-mounted signal beside the track
- On a display in the locomotive cab (Correct answer)
- On a sign at the entrance to each block
- On the dispatcher's console only
Correct answer: On a display in the locomotive cab
Cab signaling transmits coded current through the rails and displays the appropriate indication directly on instruments inside the locomotive cab.
Question 5: What does a 'Diverging Clear' signal indication permit?
- Proceed on the diverging route at maximum authorized speed
- Proceed on the main track at reduced speed
- Proceed on the diverging route at the maximum speed for that route (Correct answer)
- Stop then proceed on the diverging route at 15 mph
Correct answer: Proceed on the diverging route at the maximum speed for that route
Diverging Clear permits the train to proceed on the diverging route at the maximum authorized speed for that specific diverging route.
Question 6: Which system continuously monitors train speed and automatically applies brakes to enforce signal and speed restrictions?
- ATCS (Advanced Train Control System)
- PTC (Positive Train Control) (Correct answer)
- ABS (Automatic Block Signals)
- TWC (Track Warrant Control)
Correct answer: PTC (Positive Train Control)
Positive Train Control (PTC) is designed to automatically stop or slow a train to prevent signal violations, overspeed conditions, and unauthorized movements.
Question 7: What is the primary purpose of a 'home signal' in railroad operations?
- To indicate the train is approaching its home terminal
- To govern entry into an interlocking or a specific protected track section (Correct answer)
- To signal the engineer to contact the home dispatcher
- To indicate the maximum authorized speed for the district
Correct answer: To govern entry into an interlocking or a specific protected track section
A home signal governs the movement of trains into an interlocking or a controlled point, protecting the track layout ahead.
REC Signal Systems & Communication 3
What is 'approach locking' in signal system terminology?