Railway Engineering: Track Design

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Questions and Answers

Why should the outer track be raised when a crossover road is present?

To provide additional lateral clearance

To avoid change in cross level on the crossover road (correct)

To increase the speed restriction on the main line

To change the cross level on the crossover road

What is the primary reason for not providing straight diamond crossings in curves?

To enhance the aesthetic appeal of the track

To reduce speed restrictions

To increase the cant deficiency

To maintain uniform curvature (correct)

What is the maximum permissible speed over a diamond crossing in a curve?

65 kmph (correct)

70 kmph

60 kmph

75 kmph

What is the minimum straight length required between the curve and the heel of the acute crossing of a diamond?

50 metres Signup and view all the answers

What should be provided on curves to ensure safety?

Additional lateral clearance Signup and view all the answers

When is compensation for curvature required?

When the existing gradient when added to the curve compensation exceeds the ruling gradient Signup and view all the answers

Who decides the speed restrictions on the approach curve of a diamond crossing?

The Chief Track Engineer Signup and view all the answers

What is the purpose of repositioning posts on the cess?

To indicate zero and maximum Super-elevation Signup and view all the answers

Why should each curve be string-lined independently on double or multiple tracks?

All of the above Signup and view all the answers

What happens when the inner rail of the curve is ahead of the outer rail by an amount equal to half the pitch of boltholes?

Cut rails should be provided Signup and view all the answers

What is the formula to calculate the excess length 'd' by which the inner rail gains over the outer rail?

L x G / R Signup and view all the answers

Why are cut rails provided on curved tracks?

To obtain square joints on the inner rail Signup and view all the answers

What is the consequence of not providing cut rails on curved tracks?

The inner rail joints will not lead over the outer rail joints Signup and view all the answers

What is the purpose of remarking cant values on the inside web of the inner rail?

To indicate zero and maximum Super-elevation Signup and view all the answers

What is the definition of a cut rail?

A rail that is shorter than the standard length of rail by an amount equal to the pitch of the boltholes Signup and view all the answers

What is the formula to determine the radius of a curve?

125 × C^2 / V Signup and view all the answers

What is the unit of measurement for the radius of a curve?

Metres Signup and view all the answers

What is the degree of a curve with a radius of 1750 metres?

1° Signup and view all the answers

How often should measuring stations be located for measuring versines of a curve?

Every 10 metres Signup and view all the answers

What is the purpose of using a fishing/nylon cord or wire in measuring versines?

To measure the distance between the cord/wire and gauge face of the rail Signup and view all the answers

Which rail is taken as the reference level for level?

Inner rail of any curve Signup and view all the answers

What is the length of the chord used for measuring versines of a curve?

20 metres Signup and view all the answers

What is the length of the overlapping chord used for checking the radii of turnout and turn-in curves?

6 metres Signup and view all the answers

Study Notes

Curves and Turnouts

The outer track should be raised to avoid a change in cross-level on the crossover road, or else speed restrictions should be imposed.

Curves with Diamond Crossing

Straight diamond crossings should not be provided in curves as they produce kinks in the curve and uniform curvature cannot be obtained.
Approach curves of diamonds should be laid without cant for a distance of at least 20 metres on either side of the diamond crossing.
The cant should be uniformly run-out at the rate specified in Para 405 beyond 20 metres.
Speed restrictions on the approach curve should be decided by the Chief Track Engineer.

Extra Clearance on Curves

Additional lateral clearances should be provided on curves in excess of the fixed dimensions, between adjacent tracks and between curved track and fixed structure.

Compensation for Curvature on Gradient

Compensation for curvature should be given in all cases where the existing gradient added to the curve compensation exceeds the ruling gradient.

Determination of Radius

The radius of a curve is determined by measuring the versine on a chord of known length.
Curves can be designated by the radius in metres or by its degree.
The radius of a curve is calculated using the equation: R = 125 × C² / V

Measuring Versines

20 metres overlapping chords should normally be used with stations at 10 metres intervals for measuring versines of a curve.
For checking the radii of turnout and turn-in curves, overlapping chords of 6 metres should be used and the versine measuring stations should be located at every 3 metres.

Reference Rail for Level

The level of the inner rail of any curve is taken as the reference level.

Realigning Curves on Double or Multiple Lines

Each curve should be string-lined independently on double or multiple tracks.
No attempt should be made to realign any curve by slewing it to a uniform centre to centre distance from the realigned curve.

Cutting of Rails on Curves

Rails are usually laid with square fish-plated joints on curves.
Cut rails should be provided to obtain square joints when the inner rail of the curve is ahead of the outer rail by an amount equal to half the pitch of boltholes.
The excess length 'd' by which the inner rail gains over the outer rail is calculated by the formula: d = L × G / R

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Description

Learn about the importance of track design in railway engineering, including the placement of roads and curves, and the impact on speed and safety.