Railway Engineering Points and Crossings

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Questions and Answers

What should a pointsman ensure regarding hand points?

That the points are held down or locked. (correct)

That the points are fully automated.

That all points are labeled correctly.

That the points are adjusted regularly.

What can occur if the gauge is tight by 10 mm?

The wheel will certainly mount the nose. (correct)

The wheel will cause a derailment immediately.

The wheel will miss the edge of the nose.

The wheel will slow down significantly.

What impact does a high wing rail have on derailment risk?

It decreases the risk of derailment in both directions.

It has no impact on derailment risk.

It may cause a derailment in the trailing direction. (correct)

It solely assists in the leading direction.

Why is maintaining the correct check block clearance important?

To allow for correct passage and avoid derailments. Signup and view all the answers

What should be avoided during the renewal of wing rails?

Renewing wing rails without checking crossing conditions. Signup and view all the answers

Which of the following statements correctly defines the allowable condition of a tongue rail?

A chipped/cracked length must be under 200 mm from the toe. Signup and view all the answers

What is the maximum allowable vertical wear for a tongue rail of 60 Kg?

8 mm Signup and view all the answers

Which action is recommended if a tongue rail has developed a knife edged tip?

Immediate replacement is suggested. Signup and view all the answers

What should be done when the tongue rail is badly twisted or bent?

It should always be replaced. Signup and view all the answers

What is the purpose of providing steel packing at the toe of a switch?

To adjust for slightly wide gauge. Signup and view all the answers

At what distance from the toe of the switch must the gauge be uniform?

1000 mm Signup and view all the answers

Which condition is NOT considered under the classification of tongue rail being worn or damaged?

Vertical wear exceeding 10 mm. Signup and view all the answers

For the 52 Kg and 90R tongue rails, what is the maximum lateral wear allowed?

6 mm Signup and view all the answers

What should be done if the tongue rail is chipped to a depth of more than 10 mm over a continuous length of 10 mm?

It should be classified as damaged and replaced. Signup and view all the answers

What is the correct maximum allowable vertical wear for 75R and 60R rails?

3 mm Signup and view all the answers

What is a common consequence of an obstruction under the switches?

The points will not close effectively. Signup and view all the answers

Which issue can arise from a bent rear point rod?

Indication of points trailed through when not set. Signup and view all the answers

What role do loose heel bolts and poorly packed sleepers play in derailments?

They allow the toe of switches to lift under passing wheels. Signup and view all the answers

What could be a sign of excessive wear leading to derailment?

Switch head splitting longitudinally. Signup and view all the answers

How does the wear of stock rails affect switch performance?

It leads to unexpected wheel contact with switch heads. Signup and view all the answers

How should the flange profile of a derailed vehicle's wheel be examined?

By assessing any visible grease marks. Signup and view all the answers

What happens if the switch is worn excessively?

It results in crushing and metal flow issues. Signup and view all the answers

What risk does forcing points open during shunting operations pose?

It creates a danger for vehicles passing in the facing direction. Signup and view all the answers

What can be an indication that a point has been trailed through improperly?

Visible distortion in point rod alignment. Signup and view all the answers

What maintenance issue can prevent proper switch setting?

Inadequate heel bolt tightening. Signup and view all the answers

What is the role of the toe in a switch assembly?

To provide a tapered edge that sets against the stock rail. Signup and view all the answers

What causes the toe of the tongue rail to jump upwards?

Insufficient length of the tongue rail. Signup and view all the answers

What is the purpose of the stretcher bar in a switch assembly?

To stabilize the stock rail and prevent jumping of the tongue rail. Signup and view all the answers

Which components are included in a crossing assembly?

V rail, two wing rails, and two check rails. Signup and view all the answers

What can potentially cause a derailment in relation to the tongue rail?

A gap between the tongue and stock rail. Signup and view all the answers

What aspect is crucial in the maintenance of points and crossings according to IRPWM?

No junction fish plates at stock rail joints or heel of crossing. Signup and view all the answers

Which of the following parts is NOT included in a switch assembly?

Crossing rails. Signup and view all the answers

What is the main function of the crossing assembly in points and crossings?

To guide the movement of wheels and prevent derailment. Signup and view all the answers

What is indicated as a potential cause for badly worn wing rails or check rails?

Wide gauge at the crossing Signup and view all the answers

How much vertical wear is allowed on a wing rail or the nose of a crossing?

10 mm Signup and view all the answers

What should be recorded at stations during the inspection of turn-in curves on loops?

Versines at 1.5 m intervals Signup and view all the answers

Which position should the obtuse crossings be laid in reference to the acute crossing?

Square Signup and view all the answers

Who is responsible for the correct gauging of the switches?

PWI Signup and view all the answers

What may cause derailments at switches?

Gape in the points Signup and view all the answers

What is the distance between the throat and nose that must be maintained in obtuse crossings?

Correctly Signup and view all the answers

When must any work involving the insertion or removal of points and crossings be authorized?

Only by the Commissioner of Railway Safety Signup and view all the answers

What is a common cause for gaping points?

Bent tongue rail Signup and view all the answers

What is the primary role of the SI in relation to points and crossings?

To ensure proper fixing of interlocking apparatus Signup and view all the answers

Study Notes

Points and Crossings

Railway tracks are provided for receiving and dispatching trains
Trains need to cross other tracks to reach their destination
Points and crossings allow trains to change tracks
A set of points and crossing consists of switch assembly, crossing assembly, and lead rail joining switch and crossing assembly.

Switch Assembly

Consists of two tongue rails and two stock rails
Stock rail is part of the main rail
Tongue rail has a tapered edge (toe) that sets against the stock rail
Tapered toe prevents obstruction to wheel movement
Toe prevents jumping / rising due to weight on heel
If tongue rail is short, weight can cause toe to jump upwards
A stretcher bar is used to prevent jumping of the tongue rail
Sufficient room is needed for wheel flanges to pass through
Crossing assembly provides guidance for wheel movement

Crossing Assembly

Formed by joining V rail, two wing rails (left and right), and two check rails
Illustration of crossing assembly in provided

Important Aspects in Points and Crossing Maintenance

Junction fish plates should not be used at stock rail joints or at heel of crossing
Gauge should be uniform except near the toe of a switch
Worn/damaged stock and tongue rails should be replaced
Tongue rail assessment for wear (chipping/cracking of 200 mm within 1000 mm of toe; worn > 10mm over 10 mm length; or knife edge tip < 2 mm) triggers replacement
Vertical and lateral wear limits based on rail weight categories (60kg, 52/90R, 75/60R)
Gauge adjustments at crossings
Maintaining correct distances between throat and nose of obtuse crossings
Diamond crossings should be laid square to each other
Maximum vertical wear on wing rail/nose of crossing = 10mm

Derailments on Points and Crossings

Derailments occur at switches (points)
Gaping points or slightly bent tongue rails cause derailment
Obstructions (e.g., stones) can cause switch misalignment
Detection and immediate maintenance of defective points or crossings are crucial
Bent rear point rods indicate points not properly set
Loose heel bolts and poorly packed sleepers can cause toe lift -Excessive wear can cause longitudinal splitting
Excessive side wear can cause switch head crushing
Wheel flanges need to be assessed for sharpness (using grease marks) to identify defective wheels
Unmanned/unlocked hand-operated points are susceptible to opening slightly

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Description

This quiz focuses on the components and functionality of points and crossings in railway engineering. It covers switch and crossing assemblies, highlighting their structures, such as tongue rails and stock rails, and their operational importance. Test your knowledge on how these components ensure safe and efficient train operations.