BCE Railway 5 — Questions and Answers
Question 1: What is 'gage widening' applied on sharp railway curves?
- Intentional increase in track gauge to ease wheel negotiation (Correct answer)
- Widening of the rail head to reduce wear
- Increasing ballast width on curves
- Expanding the shoulder beyond the rail
Correct answer: Intentional increase in track gauge to ease wheel negotiation
Gauge widening (slackening) increases the track gauge slightly on sharp curves to allow the rigid wheelbase of locomotives to negotiate the curve without binding.
Question 2: The 'P-formula' in AREMA standards is used to calculate:
- Dynamic wheel load including impact factor (Correct answer)
- Rail bending stress under static loads
- Ballast pressure distribution
- Required splice bolt tension
Correct answer: Dynamic wheel load including impact factor
The AREMA P-formula calculates the equivalent dynamic wheel load by applying an impact factor to the static wheel load based on train speed.
Question 3: What is the function of a 'derail' device installed on railway sidings?
- Intentionally derail runaway cars to protect main line traffic (Correct answer)
- Detect derailments and trigger alarms
- Prevent turnouts from moving under traffic
- Measure rail deflection under load
Correct answer: Intentionally derail runaway cars to protect main line traffic
A derail is a safety device that deliberately derails any unauthorized or runaway vehicles before they can reach and endanger main line traffic.
Question 4: In railway earthwork, what is a 'borrow pit'?
- Excavation site where fill material is obtained for embankments (Correct answer)
- Pit used to store excavated spoil material
- Depression caused by soft subgrade settlement
- Test pit for soil investigation
Correct answer: Excavation site where fill material is obtained for embankments
A borrow pit is an off-site or adjacent excavation from which suitable fill material is obtained when cut material is insufficient for embankment construction.
Question 5: Which type of bridge deck is most commonly used for heavy freight railway bridges in the US?
- Open-deck with timber ties directly on stringers (Correct answer)
- Ballasted deck with concrete slab
- Steel orthotropic deck
- Filled spandrel arch deck
Correct answer: Open-deck with timber ties directly on stringers
Open-deck timber tie construction is traditional for heavy freight railway bridges, allowing direct rail fastening and easy inspection.
Question 6: What is 'wheel climb derailment' caused by?
- High L/V ratio causing flange to ride up over the rail head (Correct answer)
- Excessive train speed on tangent track
- Rail breakage under dynamic load
- Subgrade failure beneath the sleepers
Correct answer: High L/V ratio causing flange to ride up over the rail head
Wheel climb derailment occurs when the ratio of lateral force (L) to vertical force (V) exceeds the Nadal limit, causing the wheel flange to climb over the rail.
Question 7: What is the purpose of 'thermal pre-stressing' in continuously welded rail (CWR) installation?
- Lock rail in a stress-neutral state to prevent buckling and breakage (Correct answer)
- Increase rail hardness at the surface
- Improve electrical conductivity of track circuits
- Reduce rail corrugation over time
Correct answer: Lock rail in a stress-neutral state to prevent buckling and breakage
CWR is thermally pre-stressed (or stress-relieved) at a target neutral temperature so it is in neither tension nor compression at that temperature, minimizing buckling and fracture risk.
BCE Railway 5
What is 'gage widening' applied on sharp railway curves?