Minimum Distances and Heights for Structures

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the maximum width of the AXI 1755 model as indicated?

3660 mm

4.2 m

2.9 m

1755 mm (correct)

Which dimension is specifically mentioned in relation to the electrified stock?

LOA (correct)

DIM

What is the meaning of the acronym LOA in this context?

Load Operating Area

Length Of Approach

Length Over Axles

Length Overall (correct)

Which component appears to be related to the axles according to the provided information?

AXL Signup and view all the answers

Which option indicates a specification related to 'MAX.WIDE ELECTRIFIED'?

Max.WIDE Electrified SIO Signup and view all the answers

What is the minimum horizontal distance from the center of the track to any structure at a height of 300mm above rail level?

1675mm Signup and view all the answers

For structures positioned between 3355mm and 4115mm above rail level, what is the decreasing minimum horizontal distance required from the center of the track?

2135mm to 1980mm Signup and view all the answers

What is the minimum height above rail level for overhead tie bars in workshops where electric traction is not likely to be used?

5030mm Signup and view all the answers

What is the minimum height above rail level for doorways in workshops when electric traction is likely to be used?

6176mm Signup and view all the answers

What is the minimum horizontal distance from the center of the track to any structure for heights from 4115mm to 6100mm above rail level?

1370mm Signup and view all the answers

What additional clearance must be accounted for on running lines relative to goods platforms that are 1065mm above rail level?

25mm Signup and view all the answers

How much extra height must be added to the minimum required heights where electric traction is likely to be used, for every 12mm above 5410mm?

1mm Signup and view all the answers

For tunnels and through girder bridges, what is the minimum horizontal distance required from the center of the track when the height is 4420mm above rail level?

2135mm Signup and view all the answers

What is the maximum permissible speed estimated for cant deficiency value of 100mm?

Speed worked out is not specified Signup and view all the answers

What should the clearance be between live conductors and earth for short-term conditions?

200 mm Signup and view all the answers

What is the maximum height of contact wire needed to assess clearance under an existing structure?

Must account for slewing of tracks Signup and view all the answers

Which radius of curvature requires an extra clearance of 150 mm for new line/gauge conversion?

Curves lesser than 875m radius Signup and view all the answers

What is the minimum long-term clearance required from live conductors to earth?

250 mm Signup and view all the answers

When locating permanent structures on curves, what is the considered maximum cant for future speed increases?

185 mm Signup and view all the answers

What factor is NOT explicitly required when determining the permissible height of the contact wire?

Weather conditions Signup and view all the answers

What is the vertical and lateral distance required for live conductors to ensure long-term safety clearance?

250 mm Signup and view all the answers

Which of the following is a required consideration for over-dimensional consignments?

Maximum dimensions permissible Signup and view all the answers

Under what conditions should short-term clearances be measured?

For brief periods only Signup and view all the answers

What is the minimum distance center to center of tracks when re-spacing existing lines?

4495 mm Signup and view all the answers

For new works, what dimension should be adopted as the standard minimum distance between centers of tracks?

4725 mm Signup and view all the answers

What does the dotted line in the diagram represent?

Minimum outline where electric traction is not likely to be used Signup and view all the answers

When the line is on a curve, what must be done regarding the horizontal distance of any structure?

Increase the distance according to the Appendix Signup and view all the answers

What is the minimum height dimension indicated in the notes for a clearance requirement?

1830 mm Signup and view all the answers

What is the significance of the dimension 4, 6, 10, 14 mentioned for 2020/CEDO/SD/IRSOD/O/ACS-30?

Reference to multiple design parameters Signup and view all the answers

Which of the following is true about existing lines when seeking to avoid heavy alterations?

Minimum distance may be adjusted based on regulations Signup and view all the answers

In the context provided, what does '9 15 Min' represent?

Minimum distance for clearance Signup and view all the answers

What is the primary focus of the dimensions and notes provided?

To establish clearances and distances for tunnels and bridges Signup and view all the answers

What aspect does the term 'standard dimensions' primarily address in this context?

Minimum and maximum structural requirements Signup and view all the answers

What is the maximum allowable height dimension specified for the contact wire above the rail level?

3150 mm Signup and view all the answers

In the context of track design, when curves are involved, how should the horizontal distance be adjusted?

It should be increased by an amount 'D'. Signup and view all the answers

For which type of works are the specified dimensions of 4265 mm maximum applicable?

Signup and view all the answers

What is the relationship between the height of the contact wire and the super-elevation factor as described?

The formula for adjustment involves both height and super-elevation. Signup and view all the answers

Which factor must be considered when determining the horizontal distance from the center of the track on curves?

Additional amount 'D' for super-elevation. Signup and view all the answers

What implication does the note about dimensions being in millimetres have for interpretation?

Accuracy in dimensions is crucial for safety and design. Signup and view all the answers

In the context provided, what does 'minimum height for continuous covering in passenger stations' likely refer to?

Height above rail level for unrestricted movement. Signup and view all the answers

What is specifically mentioned about applying distances to straight track in the context?

Specified distances only apply to straight tracks. Signup and view all the answers

What is the maximum dimension specified for the indicated gauge in the context?

4265 mm. Signup and view all the answers

Why is it important to increase the horizontal distance by an amount 'D' only on curves?

Curves necessitate adjustments for super-elevation angles. Signup and view all the answers

What does the note about standard dimensions most critically address?

Establishing a uniform approach to design and safety. Signup and view all the answers

What is indicated about the dimensions in the context provided?

They are guidelines that can change with regulations. Signup and view all the answers

What should be done if an extension above 5410 mm is required?

Increase minimum required heights according to specific standards. Signup and view all the answers

What does the abbreviation AXI likely relate to in the provided specifications?

A model of electric rail vehicle Signup and view all the answers

Which design consideration is essential for structures positioned at varying heights above rail level?

The minimum horizontal distance from the track Signup and view all the answers

In the context of electrified stock, why is it necessary to specify the width?

To ensure compatibility with electrification infrastructure Signup and view all the answers

What consideration should be taken when planning structures around curves?

The additional horizontal distance required from the track Signup and view all the answers

What is the significance of the dimension 3660 in the specifications?

It represents a critical clearance requirement Signup and view all the answers

What is the revised minimum clearance provided between a platform on the outside of a curve and the ends of a vehicle?

127mm Signup and view all the answers

Which factor is NOT considered when calculating extra clearance on curves?

Minimum width of tracks Signup and view all the answers

How much reduction is made on the permissible clearance inside a curve as per the revised guidelines?

51mm Signup and view all the answers

What was considered excessive in the 1922 schedule regarding curves?

Superelevation for sharper curves Signup and view all the answers

What adjustment is made to the clearance on straight platforms as opposed to curved platforms?

Sway is entirely additional Signup and view all the answers

What is the maximum movement allowed due to lurching at the center of a vehicle compared to the ends?

Less than half Signup and view all the answers

According to the revisions, what is one reason the clearance between platforms and footboards was deemed dangerous?

Too large a gap causes possible falls Signup and view all the answers

What constitutes the 'additional clearance' required on the inside of a curve?

Curvature and additional vehicle sway Signup and view all the answers

What is the minimum height where DC traction is likely to be used?

140 mm Signup and view all the answers

Which maximum value is indicated in relation to the height for a specific structure clarifying its usage?

229 mm Signup and view all the answers

What is the significance of the dimension 610 in the provided standards?

Denotes a minimum height requirement Signup and view all the answers

For which height must the distance from the center of the track be diminished due to curves?

4115 mm Signup and view all the answers

What factor must be taken into account for structures located on curves according to standards?

Maximum cant adjustments Signup and view all the answers

What vertical clearance is recommended to prevent contact wire interference in existing structures?

150 mm Signup and view all the answers

What dimension should be used for the standard minimum distance between tracks?

4265 mm Signup and view all the answers

What is the maximum height for contact wire clearance indicated in the standards?

5410 mm Signup and view all the answers

What additional height must be added where electric traction is likely to be utilized?

12 mm per 100 mm Signup and view all the answers

What is the minimum height required for overhead tie bars in workshops where electric traction is not likely to be used?

1600 mm Signup and view all the answers

What factor is relevant for determining the adjustment of horizontal distances on curves according to the provided guidelines?

The super-elevation factor Signup and view all the answers

Which dimension must be assessed to determine the proper clearance above the rail level when electric traction is involved?

5410 mm Signup and view all the answers

What does the formula D = H x S / G imply regarding height adjustments on curves?

H impacts the necessity of horizontal distance adjustments Signup and view all the answers

For structures situated above 3355 mm and below 4115 mm, what is the relationship of horizontal distance needed?

The distance increases linearly with height Signup and view all the answers

In terms of standard dimensions, what critical note is associated with straight tracks?

Specified distances apply only to straight track Signup and view all the answers

Which element must be taken into account for an extension above the specified heights in relation to electric traction?

Safety clearance requirements Signup and view all the answers

What minimum height for continuous coverage is implied for passenger stations?

1200 mm Signup and view all the answers

When considering existing works, what is a key implication of the provided dimensions?

Existing works require strict adherence to maximum dimensions Signup and view all the answers

Why is it necessary to refer to specific minimum heights and distances in this context?

To ensure safety and operational efficiency Signup and view all the answers

What is indicated about the dimensions specific to electrified lines in the provided content?

They require higher clearance than non-electrified lines Signup and view all the answers

Which factor primarily affects the necessary clearance between the overhead wire and the structure?

Length of structure along tracks Signup and view all the answers

What is the minimum height of the contact wire required for a stock height of 4.42m?

4.69m Signup and view all the answers

Which of the following factors is least likely to impact the required height of the contact wire?

Type of overhead conductor Signup and view all the answers

What additional allowance is made in height clearance for track maintenance?

0.02m Signup and view all the answers

Which aspect would be important to consider when assessing the likelihood of diesel locomotives halting under a structure?

Presence of traction feeder Signup and view all the answers

When the span length of overhead equipment is 49.5m or below, how much can the minimum height of the contact wire be reduced?

0.05m Signup and view all the answers

What clearance is required between the lowest portion of a structure and the overhead wire?

Calculated after studying various factors Signup and view all the answers

In evaluating the type of structure, which of the following is NOT mentioned?

Reinforced concrete Signup and view all the answers

What is one of the factors to consider regarding the maximum number of electric locomotives per train?

Train configuration Signup and view all the answers

Which aspect least influences the determination of overhead equipment clearance?

Presence of parallel tracks Signup and view all the answers

Study Notes

Minimum Horizontal Distances for Structures

The minimum horizontal distance from the center of the track to any structure varies based on height above rail level.
From rail level to 305mm above rail level, the minimum distance is 1675mm.
From 305mm to 3355mm above rail level, the minimum distance is 2135mm.
From 3355mm to 4115mm above rail level, the distance decreases from 2135mm to 1980mm.
From 4115mm to 6100mm above rail level, the minimum distance is 1370mm.

Minimum Heights for Overhead Structures

For workshops and running sheds, the minimum height above rail level for overhead tie bars, girders, etc. depends on the use of electric traction.
Where electric traction is not likely to be used, the minimum height is 5030mm.
Where electric traction is likely to be used, the minimum height is 6176mm.

Minimum Doorway Heights

The minimum height above rail level of doorways in workshops and running sheds is determined by the use of electric traction.
For a doorway width of 1370mm on either side of the track center, where electric traction is not likely to be used, the minimum height is 4875mm.
Where electric traction is likely to be used, the minimum height is 6176mm.

A.C. Traction Clearances

For tunnels and through girder bridges with 25 kV, 50 cycles A.C. traction, the minimum horizontal distance from the center of the track to any structure is 2135mm, decreasing to 915mm from 4420mm to 5410mm above rail level.
From 4115mm to 6100mm above rail level, the minimum horizontal distance is 1370mm.

Appendix Notes

For goods platforms 1065mm above rail level that are not on a running line, a 25mm addition to the figures in column 5 of the Appendix is required.
Where electric traction is likely to be used, add 1mm for every 12mm of height above 5410mm to the figures in column 7 of the Appendix up to the height where the conductor wires are likely to be fixed.

Clearances for New Lines

For new lines, gauge conversions, and doubling, the minimum horizontal distance is 2575mm below rail level up to the formation level on straights and curves with radii of up to 875m.
For curves with radii less than 875m, the minimum distance is 2725mm.

Maximum Speed and Cant Values

The maximum permissible speed for cant deficiency values of 100mm and cant of 165mm.
However, a maximum cant of 185mm may be assumed for locating permanent structures on the side of curves on new construction and doubling on Group A routes with potential for increased speed in the future.

Clearances for 25kV AC Electric Traction

It is desirable to provide maximum possible clearances for lines equipped with 25kV AC 50 cycles single-phase electric traction.
There are both short-term and long-term clearance requirements for live conductors and earth.
Short-term clearances (brief periods) require a vertical and lateral distance of 200mm.
Long-term clearances (which may remain for a sustained period) require a vertical and lateral distance of 250mm.

Determining Permissible Contact Wire Height

To ensure sufficient clearance under existing structures, the permissible height of the contact wire must be determined.
This requires information about the structure's profile, allowance for track slewing, low joints in the tracks, track curvature, super-elevation, maximum permissible speed, dimensions of over-dimensional consignments, location of the structure in relation to level crossings, water columns, and turnouts, and the type of overhead equipment.

Standard Dimensions for Tunnels & Through Girder Bridges

Where the line is on a curve, the horizontal distance of any structure from the center of the adjacent track and the distance between track centers should be increased according to the Appendix.
When re-spacing existing lines, the minimum distance center to center of tracks may be reduced from 4725mm to not less than 4495mm to avoid significant alterations to tunnels or bridges.
The dimension of 4725mm is to be adopted for all new works.

Maximum Moving Dimensions

The maximum moving dimensions for a track gauge of 1676mm are provided in the diagram.
The dimensions include constraints for the side clearances of moving vehicles and the height of the vehicle.

Standard Dimensions in Stations

The specified distances for stations only apply to straight tracks.
On curves, the horizontal distance should be increased by an amount 'D' to account for the lean due to super-elevation.
This adjustment is calculated using the formula: D = H x S / G, where H is the contact wire height, S is the super-elevation, and G is the track gauge, all dimensions in meters.
The minimum height for a continuous covering in passenger stations is also provided.
The diagram specifies dimensions for the maximum width of electrified stock and the maximum dimensions for existing and new construction.

Extra Clearance on Curves

Extra clearance for curved tracks should be provided according to columns 5, 6, 7 and 8 instead of column 9.
The appendix detailing extra clearance on curves has been revised to include maximum speeds, corresponding superelevation, and the required clearances.

Rationale for Revisions

The clearance provided in the 1913 and 1922 schedules was considered too liberal, causing dangerous gaps between platforms and footboards.
In the 1922 schedule, sway allowance for carriages was treated as an addition to existing clearance on straight tracks, not accounting for the additional sway on curved tracks.
The amount of superelevation was also excessive on sharper curves.

Reduced Clearance on Curves

The clearance between a vehicle (footboards) and the platform coping on a straight track is 152mm.
To reduce the average distance between a curved platform and foot boards, the minimum clearance on the outside of a curve can be reduced to 127mm.
The clearance between the center of a vehicle and the platform on the inside of a curve can be safely reduced to 102mm due to reduced lurching at the vehicle’s center.
Therefore, extra allowances on curves in paragraphs 5, 6, 7, and 8 have been reduced by 51mm on the inside and 25mm on the outside of curves.

Considerations for Contact Wire Height

The additional clearance on the inside of a curve must account for curvature, lean due to superelevation, and additional sway of vehicles over that already accounted for on straight tracks.
The additional clearance on the outside of a curve must account for the effect of curvature.
The clearance between the lowest portion of a bridge or structure and the topmost position of the overhead wire is determined using the following factors:
- System of tensioning of the overhead equipment
- Atmospheric conditions
- Maximum permissible number of electric locomotives per train
- Location of the structure in relation to points, crossings, overlaps, spans, etc.
- Length of the structure along the tracks
- Type of structure (girder, masonry, etc.)
- Span of overhead equipment under the bridge
- Presence of traction feeder
- Likelihood of diesel locomotives halting under the structure

Minimum Height of Contact Wire

The minimum height of contact wire for stock height of 4.42m running on sections electrified with 25 kV A.C. traction system with live traction overhead equipment is 4.69m.
This minimum height is determined by adding the height of the locomotive (4.42m), minimum clearance to contact wire (0.25m), and allowance for track maintenance (0.02m).
For OHE span lengths of 49.5m or below, the oscillation of the contact wire is reduced to 0.05m, allowing for a reduced minimum height of the contact wire to 4.64m.