PTS Railway Hazards and Terminology 5

Question 1

What is a 'SPAD' (Signal Passed At Danger) in railway safety?

Accepted Answer

An incident where a train passes a signal displaying a stop aspect without authority

Answer

A track defect report filed after a routine inspection

Answer

A scheduled possession activity document issued by the controller

Answer

A speed restriction imposed after adverse weather conditions

Question 2

Which of the following best describes the hazard of 'trespass' on railway property?

Accepted Answer

Exposure to moving trains, electrified equipment, and other hazards without protection or warning

Answer

Legal liability for the trespasser only, with no direct safety risk to others

Answer

A minor risk managed entirely by perimeter fencing along the line

Answer

A hazard that only exists during hours of darkness

Question 3

What does 'track circuit block' (TCB) signaling rely on to detect trains?

Accepted Answer

The electrical conductivity of steel wheels bridging a low-voltage circuit between the two rails

Answer

GPS transponders fitted to every locomotive and wagon

Answer

Infrared sensors mounted at regular intervals at the trackside

Answer

Weight sensors embedded in the sleepers under each rail

Question 4

What is the primary hazard when working inside a non-electrified railway tunnel?

Accepted Answer

Falling debris from the tunnel roof combined with very limited escape routes if a train approaches

Answer

Excessive heat buildup caused by trains passing through in both directions

Answer

Tunnel acoustics magnifying distant train noise, making warnings inaudible

Answer

Risk of flooding from underground water tables beneath the invert

Question 5

What is 'rail creep' and what structural problem can it cause?

Accepted Answer

Gradual longitudinal movement of rails due to traction and braking forces, which can open or close rail joints dangerously

Answer

Slow lateral spreading of rails on curves due to centrifugal forces

Answer

Progressive sinking of the track into soft subgrade over time

Answer

Corrosion of fasteners that allows the rail to rotate in its rail seat

Question 6

What does 'degraded mode working' mean in a railway signalling context?

Accepted Answer

Operating the railway under alternative rules when normal signalling equipment has failed

Answer

Operating trains at reduced power to conserve energy during off-peak hours

Answer

Reducing train frequency during periods of severe staff shortages

Answer

Using older mechanical signals instead of electronic ones during planned maintenance windows

Question 7

What is 'differential settlement' of track and why does it create a derailment risk?

Accepted Answer

Uneven sinking of the track formation at different rates, creating twist or vertical misalignment in the track geometry

Answer

The difference in wear rate between inner and outer rails on a curve

Answer

Variation in sleeper spacing that develops progressively over years of heavy traffic

Answer

Settlement of ballast on one side causing gauge widening on a straight section