Railway Track Maintenance and Alignment

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Questions and Answers

In what direction are emergency crossovers between double or multiple straight lines laid?

trailing direction

What type of turnouts may be used for snag dead end?

1 in 8½ symmetrical split turnouts

Why is it desirable to avoid laying turnouts on curved main lines?

due to maintainability and comfort considerations

What is the minimum radius of the main line curve and resultant lead curve radius when laying turnouts with 1 in 12 or flatter crossings?

350m Signup and view all the answers

From which part of a curved track should 1 in 8.5 turnouts not be laid?

inside Signup and view all the answers

Under what circumstances can 1 in 8½ turnouts with curved switches be laid from outside of a curve?

up to five degrees in exceptional circumstances with PCE approval Signup and view all the answers

Why is it essential to select the proposed versines carefully in re-alignment solution?

To obtain a suitable re-alignment solution Signup and view all the answers

What is the purpose of using a steel tape in staking out the revised alignment of the curve?

To measure the distance from the face of the pegs to the outer edges of the inner rail Signup and view all the answers

Why may it be necessary to drive pegs on the outer cess in narrow cuttings or tunnels?

Because the face of the cutting may foul the fishing cord Signup and view all the answers

What should be verified after measuring the versines on the pegs?

That they correspond to the final versines of the re-alignment solution Signup and view all the answers

Where should the pegs not be fixed?

On formation that is not firm or at locations where they are liable to be disturbed or tampered with Signup and view all the answers

What should be done after slewing the curve to the revised alignment?

Correct Super-elevation should be provided at each station Signup and view all the answers

What is the importance of paying attention to the run-off on the transition?

To ensure correct Super-elevation Signup and view all the answers

What is the purpose of Operation No. 3 in the re-alignment process?

Slewing the curve to the revised alignment Signup and view all the answers

What type of features should be recorded that restrict slewing of the track?

Features that restrict slewing of the track either inwards or outwards Signup and view all the answers

What should be measured and recorded against each station?

Existing Super-elevation Signup and view all the answers

What is the purpose of recording the versine in a curve?

To measure the cant and restrictions to slewing Signup and view all the answers

How should the versine survey be conducted in the case of reverse curves?

Continuously, transferred to the outer rail at points where the curvature changes sign Signup and view all the answers

What information should be included in the record of the survey?

Curve details, station names, date of survey, and jurisdiction of JE/SSE/P.Way (In-Charge) / (Sectional) Signup and view all the answers

What is the purpose of recording the 'remarks regarding restrictions to slewing'?

To note any obstacles or limitations that restrict slewing Signup and view all the answers

What is the significance of the 'GB' notation in the remarks column?

It indicates an obligatory point Signup and view all the answers

Why is it essential to record the 'High Bank, Moorum, etc.' in the remarks column?

To note any unusual features or conditions of the terrain Signup and view all the answers

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

Because the existing track centres may not be uniform, and slewing one curve to a uniform centre may entail a larger slew on the adjacent track. Signup and view all the answers

What is the purpose of cutting rails on curves?

To obtain square joints on curved tracks. 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 on a curve?

d = (L × G) / R 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 to obtain square joints. Signup and view all the answers

Why is it important to remark 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 purpose of repositioning posts on the cess?

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

Why do transitions at the entry and exit of curved tracks have different lengths?

Because the degree of circular curves may be nearly the same, but the transitions are impractical to maintain uniform track centres. Signup and view all the answers

What is a cut rail?

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

What is the requirement for laying points and crossings?

Points and crossings should be laid without the 1 in 20 cant unless otherwise specified in the drawing. Signup and view all the answers

What is the restriction on junction fishplates in points and crossings?

There should be no junction fishplates at stock rail joints or at the heel of crossings. Signup and view all the answers

What is the requirement for the section of rails on either side of points and crossings?

At least one rail on either side of the points and crossings should have the same section as the points and crossings assembly rail section. Signup and view all the answers

What is the preferred method of joining stock and lead joints on points and crossings assembly?

It is desirable to weld stock and lead joints on the points and crossings assembly. Signup and view all the answers

Where are spherical washers used in points and crossings assembly?

The spherical washers are used on skew side, and invariably on the left side in switch assembly. Signup and view all the answers

What is the importance of correct spacing of sleepers in points and crossings?

Correct spacing of sleepers should be ensured according to the standard layout drawings. Signup and view all the answers

What is the requirement for the track geometry at the turnout?

The track geometry at the turnout should not be inferior to that applicable for the route. Signup and view all the answers

What is the requirement for clearance at the toe, heel of switch, at checkrail and wing rail?

The clearance, at the toe, heel of switch, at checkrail and wing rail must be maintained within the tolerances prescribed in the schedule of dimensions. Signup and view all the answers

Study Notes

Track Alignment and Maintenance

Emergency crossovers between double or multiple straight lines can be laid with 1 in 8½ crossings in the trailing direction.
1 in 8½ symmetrical split turnouts may be used for snag dead ends.
Turnouts have inbuilt curvature as part of their design, and laying them on curved main lines should be avoided for maintainability and comfort reasons.

Laying Turnouts on Curved Main Lines

If laying turnouts on curved main lines is unavoidable, the following stipulations apply:
- For 1 in 12 or flatter crossings, the resultant lead curve radius and main line curve radius should not be less than 350m.
- 1 in 8.5 turnouts should not be laid from the inside of a curved track.
- 1 in 8½ turnouts with curved switches may be laid from the outside of a curve up to five degrees in exceptional circumstances with PCE approval.

Realigning Curves

To achieve a suitable realignment solution, proposed versines should be selected carefully.
A numerical example is given in Table 1 to illustrate the method of working out the solution for realignment of a curve.
The revised alignment of the curve should be staked out with a steel tape by using pegs cut from bars or wooden stakes with tack marks.

Slew Operations

The curve should be slewed to the revised alignment with reference to the pegs.
Super-elevation should be provided at each station to accord with the curvature, with attention paid to run-off on the transition.
Certain features that restrict slewing of the track either inwards or outwards should be recorded.

Recording Track Geometry

The existing super-elevation should be measured and recorded against each station.
The record obtained should be in the following form, including station, versine, cant existing, and remarks regarding restrictions to slewing.

Realignment of Curves on Double or Multiple Lines

Each curve on double or multiple tracks should be string-lined independently.
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' can be calculated by the formula: d = L × G / R.

Inspection and Maintenance of Points and Crossings

Points and crossings should be laid without 1 in 20 cant unless otherwise specified in the drawing.
There should be no junction fishplates at stock rail joints or at the heel of crossings.
At least one rail on either side of the points and crossings should have the same section as the points and crossings assembly rail section.

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Description

This quiz covers the alignment and maintenance of railway tracks, including the use of emergency crossovers, symmetrical split turnouts, and laying turnouts on curved main lines. It focuses on the design and maintenance considerations for railway tracks.