Upgrading Turnout and Loop Speeds to 30 Kmph

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Questions and Answers

What is the minimum rail section required for turnouts on running loops?

45 kg/m

60 kg/m

52 kg/m (correct)

40 kg/m

What is the sleeper density required on running loops?

1700 Nos.per km

1540 Nos.per km (correct)

1400 Nos.per km

1200 Nos.per km

What is the permissible speed for 1 in 12 curved switch?

20 Kmph

30 Kmph

40 Kmph

50 Kmph (correct)

What type of switch is required on turnouts on running loops?

Curved switch Signup and view all the answers

What is the minimum sleeper spacing required on turn-in curves?

65 cm centre to centre Signup and view all the answers

What is the purpose of providing extra shoulder ballast on the outside of the turn-in curve?

For improving drainage Signup and view all the answers

What is the purpose of welding rail joints on turnouts?

To increase permissible speed Signup and view all the answers

What is the minimum permissible speed on turnouts laid on PSC sleepers?

15 Kmph Signup and view all the answers

What is the purpose of the curve board provided at the tangent point of a curve?

To indicate the radius of the curve, length of the curve, and maximum cant Signup and view all the answers

What is the purpose of the rail posts on the inside of the curve?

To indicate the positions of the beginning and end of the transition curves Signup and view all the answers

What is the special case of Super-elevation run out that may be approved?

Run out approved by the Chief Track Engineer Signup and view all the answers

What is the typical color scheme used for the rail posts?

Red and white Signup and view all the answers

Where is the curve board typically placed?

On the tangent point of the curve Signup and view all the answers

What information does the curve board provide?

The length of the curve, the length of the transition curve, and the maximum cant Signup and view all the answers

What is the purpose of the rail posts on the tangent track and on the circular curve?

To indicate the beginning and end of the virtual transition Signup and view all the answers

What type of curve is referred to when rail posts are erected on the tangent track and on the circular curve?

Non-transitioned curve Signup and view all the answers

What is the cumulative spacing from SRJ at point 1?

268 Signup and view all the answers

What is the spacing at point 20?

598 Signup and view all the answers

At which point does the spacing change from 600 to 550?

43 Signup and view all the answers

What is the cumulative spacing at point 15?

8833 Signup and view all the answers

What is the spacing at point 10?

600 Signup and view all the answers

At which point does the cumulative spacing exceed 15000?

40 Signup and view all the answers

What is the cumulative spacing at point 5?

2773 Signup and view all the answers

What is the spacing at point 2?

600 Signup and view all the answers

What is the purpose of keeping the original rail face as the base until the change is certain?

To ensure accurate versine readings Signup and view all the answers

What should be recorded at every station where there are two or more lines?

Track centres Signup and view all the answers

What is the basic principle of string lining which states that the sum total of the existing versines should be equal to the sum total of the proposed versines?

The sum total of the existing versines should be equal to the sum total of the proposed versines Signup and view all the answers

What is the effect of a slew in any direction at a station on the versine values at the adjacent stations?

It affects the versine values by half the amount in the opposite direction Signup and view all the answers

What does the second summation of versine difference between proposed versine and existing versine represent?

Half the slew at any station Signup and view all the answers

What should be the slew at the first and at the last station?

Zero Signup and view all the answers

What is the purpose of selecting proposed versines in a certain way?

To obtain uniform rate of change of versines over the transition curve Signup and view all the answers

What should be calculated to obtain a realignment solution?

The calculations in the manner given in Table-1 Signup and view all the answers

Why must the outer track be raised in a cross over road?

To avoid change in cross level Signup and view all the answers

What is the minimum distance on either side of the diamond crossing where the cant should be uniformly run-out?

20 metres Signup and view all the answers

Why are speed restrictions imposed on the approach curve?

All of the above Signup and view all the answers

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

50 m Signup and view all the answers

What is the purpose of providing extra clearance on curves?

To provide additional lateral clearance Signup and view all the answers

Why is compensation for curvature necessary?

To compensate for the existing gradient Signup and view all the answers

What is the maximum permissible speed over the diamond crossing?

65 Kmph Signup and view all the answers

Who decides the speed restrictions on the approach curve?

Chief Track Engineer Signup and view all the answers

Study Notes

Up-gradation of Speeds on Turnouts and Loops to 30 Kmph

Up-gradation of speeds on turnouts should cover a number of contiguous stations at a time to derive a perceptible advantage of the higher speed in train operation.
Works described should cover all the running loops on the stretch of line taken up.
Turnouts on the running loops should be laid with curved switches, with a minimum rail section of 52 kg/m.
All rail joints on these turnouts should also be welded to the extent possible.
Permissible speeds for different types of curved switches are:
- 1 in 8½ curved switch: 15 Kmph
- 1 in 8½ symmetrical split with curved switches: 30 Kmph
- 1 in 12 curved switch: 30 Kmph (50 Kmph for TWS)
The minimum track structure on the running loops should be 52 kg/m rails laid as Short Welded Panels, sleeper density 1540 Nos. per km, and 150 mm clean ballast cushion.
Proper drainage of the area should also be ensured.

Turn-in Curves

Turn-in curves should be laid with the same rail section as on the turnout with PSC sleepers.
Sleeper spacing should be 65 cm centre to centre (maximum).
Turn-in curve should conform to Para 408(2) and especially so in respect of curvature of the lead curve.
Extra shoulder ballast of 150 mm should be provided on outside of the turn-in curve.

Indicators/Boards Provided in Curves

Each approach of a curve should be provided with a curve board at the tangent point fixed on the outside of the curve.
The board should indicate the radius of the curve, the length of the curve, length of transition in metres, and the maximum cant provided on the circular portion of curve in millimetres.
Rail posts indicating tangent points should be erected on each approach of the curve, to indicate the positions of the beginning and end of transition curves.

Curves with Diamond Crossing

Straight diamond crossings should not be provided in curves as these produce kinks in the curve and uniform curvature cannot be obtained.
Where provision of such diamonds cannot be avoided, the approach curves of these diamonds should be laid without cant for a distance of at least 20 metres on either side of the diamond crossings.
The cant should be uniformly run-out at the rate specified in Para 405 beyond 20 metres.

Extra Clearance on Curves

On curves, additional lateral clearances, in excess of the fixed dimensions, should be provided as laid down in the Schedule of Dimensions.
Clearances should be provided 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 when added to the curve compensation exceeds the ruling gradient.

Realignment of Curves

The basic principles of string lining are as follows:
- The chord length being identical, the sum total of the existing versines should be equal to the sum total of the proposed versines.
- The slew in any direction at a station affects the versine values at the adjacent stations by half the amount in the opposite direction, when the track is not disturbed at the adjacent stations.
- The second summation of versine difference between proposed versine and existing versine represents half the slew at any station.
- At the first and at the last station, the slews should be zero.

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Description

This quiz covers the up-gradation of speeds on turnouts and loops to 30 km/h, including the length of section, works, and speed permits. It's essential for train operation and infrastructure management.