FRA Signal Systems & Train Control 3 — Questions and Answers
Question 1: What is the function of the 'vital' logic in a solid-state interlocking (SSI) system?
- To manage train scheduling and dispatching
- To ensure fail-safe operation so any failure defaults to a safe state (Correct answer)
- To increase processing speed for signal changes
- To communicate cab signal codes to locomotives
Correct answer: To ensure fail-safe operation so any failure defaults to a safe state
Vital logic in solid-state interlockings is designed so that any component failure causes the system to default to the most restrictive, safe state.
Question 2: What does a 'time release' in interlocking logic accomplish?
- It automatically resets signals after a predetermined time with no train detected
- It delays signal changes to allow train movements to clear conflicting routes (Correct answer)
- It tests signal bulbs on a timed schedule
- It sends timed pulses to cab signal receivers
Correct answer: It delays signal changes to allow train movements to clear conflicting routes
Time releases delay the clearing of conflicting routes or signals until sufficient time has passed for a train to have cleared the interlocking.
Question 3: According to FRA rules, what defines 'restricted speed' in signal territory?
- A speed not exceeding 15 mph, prepared to stop in half the range of vision
- A speed not exceeding 20 mph, prepared to stop within the range of vision (Correct answer)
- A speed not exceeding 10 mph at all times
- A speed not exceeding 25 mph on straight track only
Correct answer: A speed not exceeding 20 mph, prepared to stop within the range of vision
Restricted speed is defined as a speed not exceeding 20 mph while prepared to stop within the range of vision, short of a train, obstruction, or misaligned switch.
Question 4: Which FRA-regulated system uses transponders embedded in the track to provide location and authority information directly to the locomotive?
- Automatic Train Stop (ATS)
- Automatic Block Signal (ABS)
- Communication-Based Train Control (CBTC) (Correct answer)
- European Train Control System (ETCS)
Correct answer: Communication-Based Train Control (CBTC)
CBTC systems use trackside transponders (balises) to provide precise location data and movement authorities to equipped locomotives.
Question 5: What is the maximum civil penalty per violation per day under 49 CFR for failing to maintain required signal system records?
- $5,000
- $10,000
- $25,000 (Correct answer)
- $50,000
Correct answer: $25,000
FRA may assess civil penalties up to $25,000 per violation per day for violations of signal and train control regulations under 49 CFR Part 236.
Question 6: In a two-indication block signal system, what does a red (stop) indication require of the train crew?
- Reduce speed to 30 mph
- Stop before the signal (Correct answer)
- Proceed at restricted speed
- Notify the dispatcher and continue
Correct answer: Stop before the signal
A red indication at an absolute signal requires the train to stop and not proceed past the signal without proper authority.
Question 7: What does the term 'approach locking' prevent in an interlocking?
- A switch from moving while a train is approaching on a conflicting route (Correct answer)
- A signal from displaying green before track circuits are clear
- A train from entering an interlocking above authorized speed
- A dispatcher from clearing conflicting routes simultaneously
Correct answer: A switch from moving while a train is approaching on a conflicting route
Approach locking prevents a switch from being moved after a signal has been cleared and a train is approaching, protecting the train's expected route.
FRA Signal Systems & Train Control 3
What is the function of the 'vital' logic in a solid-state interlocking (SSI) system?