Requirements for Defining and Maintaining Clearances Iss 1.pdf · Requirements for Defining and Maintaining Clearances 2 RAILWAY SAFETY Railway Group Standard GC/RT5212 Issue One

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Railway Group Standard GC/RT5212 Issue One Date February 2003

Requirements for Defining and Maintaining Clearances

Synopsis This document mandates requirements for monitoring and maintaining clearances. It also mandates requirements for new, altered and temporary infrastructure relating to clearances; gauging conditions for passage of exceptional loads; standard vehicle gauges; and data relating to gauging and clearances, to be provided to Railway Group members and their suppliers.

Signatures removed from electronic version

Submitted by

Jonathan Ronda Standards Project Manager

Authorised by

Anne E Blakeney Acting Controller, Railway Group Standards

This document is a NOTIFIED STANDARD in the context of the European directives

for interoperability of railway systems

Uncontrolled When Printed Document ceases to be in force with effect from 05/03/2016 and is superseded by GIRT7073 Iss 1 on 05/03/2016

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Railway Group Standard GC/RT5212 Issue One Date February 2003 Page 1 of 33

Contents Section Description Page

Part A A1 Issue record 3 A2 Implementation of this document 3 A3 Scope of Railway Group Standards 3 A4 Responsibilities 3 A5 Health and safety responsibilities 4 A6 Technical content 4 A7 Supply 4

Part B B1 Purpose 5 B2 Application of this document 5 B3 Definitions 7 B4 Principles 9

Part C Control measures for clearances C1 Introduction 11 C2 Categorisation of clearances 11 C3 Required control methods 12 C4 Records of clearances and control measures 13

Part D Calculation of clearances D1 Method of calculation 15 D2 Measurement accuracy 16 D3 Track tolerances 16 D4 Adjustment for cross-wind 17 D5 Track quality data 17

Part E Determining the relative positions of tracks and structures E1 Need for measurement 19 E2 Detailed requirements for measurements 19 E3 Accuracy of measurement 20 E4 Records of the relative positions of tracks and structures 20 E5 Reassessment of the relative positions of tracks and structures 20

Part F Monitoring and maintaining the relative positions of tracks and structures F1 Need for monitoring 22 F2 Selection of monitoring systems 22 F3 Frequency of monitoring 22 F4 On-site information defining the relative positions of tracks and structures 22 F5 Actions to correct the relative positions of tracks and structures 24

Part G Requirements for new, altered and temporary infrastructure G1 Minimum upper sector clearances for new infrastructure 25 G2 Lower sector structure gauge for new infrastructure 25 G3 Track intervals for new infrastructure 25 G4 Alterations to existing infrastructure 26 G5 Temporary infrastructure 26 G6 Requirements of HM Railway Inspectorate 26

Part H Exceptional Loads H1 Gauging conditions for passage of exceptional loads 27



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Part J Standard vehicle gauges J1 Requirement to have standard vehicle gauges 28 J2 Application rules for standard vehicle gauges 28 J3 Availability of sections of track for standard vehicle gauges 28

Part K Data to be provided to Railway Group members and their suppliers K1 Requirement to provide information 29 K2 Processes for providing information 29

Appendices 1 Lower sector structure gauge 30

References 33

(Part I has not been used, to avoid potential confusion between upper case ‘I’, lowercase ‘l’ and the number ‘1’)



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Part A A1 Issue record

Issue Date Comments

One February 2003 Original document, supersedes parts of GE/RT8029.

This document is to be updated when necessary by distribution of a complete replacement.

A2 Implementation of this document

The publication date of this document is 1 February 2003.

This document comes into force on 5 April 2003.

The dates by which compliance with the requirements of this document is to be achieved are set out in Part B2. Where those dates are later than the date on which this document comes into force, this is to give Railway Group members additional time to plan and commence implementation so as to achieve full compliance by the dates set out in Part B2.

This document supersedes the following Railway Group Standards, either in whole or in part as indicated:

Railway Group Standard

Issue No. Title RGS sections superseded by this document

Date(s) as of which sections are superseded

GE/RT8029 One Management of Clearances and Gauging

All except section 14

5 April 2003

GE/RT8029 is withdrawn with effect from 5 April 2003.

Section 14 of GE/RT8029, dealing with gauging authority, is superseded by GE/RT8270 Route Acceptance of Rail Vehicles (which refers to ‘gauging acceptance’, rather than ‘gauging authority’). Some parts of GE/RT8029 dealing with out-of-gauge loads have been withdrawn, as their requirements are duplicated in GO/RT3407 Train Operation - Exceptional Load Documentation.

A3 Scope of Railway Group Standards

The overall scope of Railway Group Standards is set out in Appendix A of GA/RT6001. The specific scope of this document is set out in Part B2.

A4 Responsibilities Railway Group Standards are mandatory on all members of the Railway Group* and apply to all relevant activities that fall into the scope of each individual’s Railway Safety Case. If any of those activities are performed by a contractor, the contractor’s obligation in respect of Railway Group Standards is determined by the terms of the contract between the respective parties. Where a contractor is a duty holder of a Railway Safety Case then Railway Group Standards apply directly to the activities described in the Safety Case.

* The Railway Group comprises Railtrack PLC, Railway Safety, and the train and station operators who hold railway safety cases for operation on or related to infrastructure controlled by Railtrack PLC.

Railtrack PLC is known as Railtrack.



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A5 Health and safety responsibilities

In issuing this document, Railway Safety makes no warranties, express or implied, that compliance with all or any documents published by Railway Safety is sufficient on its own to ensure safe systems of work or operation. Each user is reminded of its own responsibilities to ensure health and safety at work and its individual duties under health and safety legislation.

A6 Technical content The technical content of this document has been approved by:

Jon Taylor, Principal Track and Structures Engineer, Railway Safety

Enquiries should be directed to Railway Safety – Tel: 020 7904 7518

A7 Supply Controlled and uncontrolled copies of this document can be obtained from the Industry Safety Liaison Dept, Railway Safety, Evergreen House, 160 Euston Road, London NW1 2DX.



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Part B B1 Purpose

This document mandates requirements for monitoring and maintaining the position of the track relative to adjacent structures and tracks, to ensure that rail vehicles do not approach infrastructure or other vehicles too closely. It also mandates requirements for new, altered and temporary infrastructure relating to clearances; gauging conditions for passage of exceptional loads; standard vehicle gauges; and data relating to gauging and clearances, to be provided to Railway Group members and their suppliers.

B2 Application of this document

B2.1 To whom the requirements apply This document contains requirements that are applicable to duty holders of the infrastructure controller category of Railway Safety Case.

B2.2 Compliance requirements This document applies to all Railtrack controlled infrastructure (existing, new, altered and temporary).

B2.2.1 Compliance with Part C of this document The requirements of Part C of this document (Control measures for clearances) shall be complied with no later than 5 April 2003, with the exceptions set out below.

Compliance with the requirement to provide information on site, defining the relative positions of structures and adjacent tracks as a control measure, set out in section C3 is required no later than 4 December 2004 (see also section B2.2.4).

B2.2.2 Compliance with Part D of this document The requirements of Part D of this document (Calculation of clearances) shall be complied with no later than 5 April 2003, with the exception set out below.

Compliance with section D5 (Track quality data) is required no later than 4 December 2004.

B2.2.3 Compliance with Part E of this document The requirements of Part E of this document (Determining the relative positions of tracks and structures) shall be complied with no later than 5 April 2003.

B2.2.4 Compliance with Part F of this document The requirements of Part F of this document (Monitoring and maintaining the relative positions of tracks and structures) shall be complied with no later than 5 April 2003, with the exception set out below.

Compliance with section F4 (On-site information defining the relative positions of tracks and structures) is required no later than 4 December 2004.

B2.2.5 Compliance with Part G of this document The requirements of Part G of this document (Requirements for new, altered and temporary infrastructure) are mandatory for new, altered and temporary Railtrack controlled infrastructure for which Approval in Principle is given on or after 5 April 2003.

When Approval in Principle is given before 5 April 2003, but the infrastructure has not yet been brought into service, the design shall be reviewed and, where reasonably practicable, brought into line with the requirements of this document. Where it is not reasonably practicable to do so, the situation shall be regularised by means of a non-compliance or derogation (see section B2.2.9).



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B2.2.6 Compliance with Part H of this document The requirements of Part H of this document (Exceptional loads) shall be complied with no later than 5 April 2003.

B2.2.7 Compliance with Part J of this document The requirements of Part J of this document (Standard vehicle gauges) shall be complied with no later than 4 December 2004.

B2.2.8 Compliance with Part K of this document The requirements of Part K of this document (Data to be provided to Railway Group members and their suppliers) shall be complied with no later than 5 April 2003, except where the availability of data to be supplied is dependent on a later compliance date, when that later date shall apply.

B2.2.9 General compliance requirements Until the compliance dates, or the date by which compliance is achieved (if earlier), the applicable requirements of the predecessor documents shall continue to be met (see Part A for details).

After the compliance dates, or after the date by which compliance is achieved (if earlier), Railway Group members shall not deviate from the requirements set out in this document.

Where it is considered not reasonably practicable to comply with the requirements set out in this document, authorisation not to comply shall be sought in accordance with GA/RT6001, GA/RT6004 or GA/RT6006.

B2.3 Exclusions from the application of this document The requirements of this document do not apply to clearances to road rail vehicles, rail mounted maintenance machines or on-track machines operating within a possession. Requirements for a safe system of work in these cases, taking account of infrastructure obstructions and adjacent lines open to traffic, are set out in GM/RT1403.

B2.4 Related requirements in other documents The requirements for means of access along running lines, provided for authorised people, are set out in GC/RT5203. These include requirements for cess walkways and continuous positions of safety that specify clearances greater than the minimum clearances set out in this document.

Requirements for the management of stepping distances between trains and platforms are set out in GC/RT5161.

Requirements for electrical clearances to the live parts of overhead line equipment and pantographs, and to the live parts of third rail electrification systems, are set out in GE/RT8025.

Methods of determining the size of railway vehicles are set out in GM/RT2149. It also sets out requirements for the format of the prescribed parameters for defining the size of railway vehicles.

Requirements and responsibilities for route acceptance of rail vehicles for operation on Railtrack controlled infrastructure are set out in GE/RT8270. These requirements include requirements for granting of gauging acceptance.

The process for producing and issuing exceptional load (including out-of-gauge load) conditions of travel documentation for train operation are set out in GO/RT3407.

The means by which tilting trains are permitted to utilise the tilt mechanism over routes, parts of which contain sections where tilting is prohibited due to clearance limitations, are set out in GE/RT8019 Tilting Trains: Controlling Tilt Systems to Maintain Clearances.



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Requirements for reporting safety related information are set out in GE/RT8047. These include requirements to report collisions between trains and any case of a train on a running line striking an object.

B3 Definitions Absolute gauging Absolute gauging of a vehicle is a full assessment of clearances on a section of track between the vehicle and fixed infrastructure, and between the vehicle and vehicles on adjacent tracks.

Alignment fault A fault in the alignment of track that the infrastructure controller’s standards, procedures, specifications or contract documents requires to be corrected within a defined timescale.

Altered infrastructure Infrastructure subject to alteration. This term does not refer to infrastructure that has been altered at some time in the past.

ARL Abbreviation for ‘above rail level’, measured perpendicularly to the plane of rails.

Clearance The minimum calculated distance between vehicles and fixed structures or between two vehicles on adjacent tracks.

Comparative gauging The process of comparing the swept envelopes of a vehicle new to a route, with the swept envelopes of a vehicle or vehicles which have been demonstrated to be able to use the proposed route.

Effective position of the track A position that the track could credibly occupy in relation to structures or an adjacent track at some point within its maintenance cycle, giving the smallest clearances. Compare with ‘Maintained position of the track’.

Exceptional load A vehicle or vehicle load that is subject to special operating arrangements, which are determined before authority to travel is granted.

Exposed route A route (or section of route) which is orientated generally in a north-south direction and which features hillsides, embankments or viaducts which are open and exposed to south-westerly winds. Examples of such routes are: West Coast Main Line north of Weaver Junction, and the Cumbrian Coast Line.

Fixed datum A reference monument fixed to a structure which allows the relative position of the track and structure to be checked.

Gauging The process by which swept envelopes of a vehicle or a standard vehicle gauge are used to determine clearances on a section of track between the vehicle and fixed structures and between the vehicle and vehicles on adjacent tracks.

Gauging acceptance The endorsement by the infrastructure controller that a vehicle has satisfactorily completed the gauging process for a route, in accordance with GE/RT8270.

Hybrid gauging A combination of comparative and absolute gauging where absolute gauging is used to evaluate the clearances related to features of the vehicle projecting outside the envelope of the comparator vehicle.



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Infrastructure For the purpose of this document, track and structures in combination. Compare with ‘structure’.

Lower sector The area up to and including 1100 mm above the plane of the rails. See also ‘upper sector’.

Maintained position of the track The position in which the track should be placed during maintenance. Compare with ‘Effective position of the track’.

New infrastructure Infrastructure other than that which already exists.

Normal clearance A clearance between a structure and a vehicle or between passing vehicles which does not require specific controls on the position of the track, but which does require the relative locations of structures and adjacent tracks to be monitored and maintained.

Out-of-gauge load An exceptional load, by virtue of its size.

Passing clearance The minimum calculated distance between the swept envelopes of two specific types of rail vehicle as they pass on adjacent tracks at nominated speeds, taking account of appropriate track tolerances and accuracy of measurement.

Permissible or enhanced permissible speed The maximum speed published in the Sectional Appendix at which traffic is allowed to run on a line.

Plane of the rails An imaginary surface coplanar with the top of both rails of a track.

Reduced clearance A clearance, less than a normal clearance, which requires special measures to maintain tracks relative to adjacent tracks and structures.

Route The physical path of a journey to be undertaken by a vehicle or a collection of vehicles, where the path is comprised of a number of track sections, each of which has individually defined characteristics.

Section of track Track bounded by identified limits such as junctions, terminals or points at which there is a significant change in traffic flow or permissible speed.

Special reduced clearance A clearance, less than a reduced clearance, which requires a specific risk assessment to be undertaken and the implementation of appropriate controls to demonstrate that risks have been reduced to as low as reasonably practicable.

Standard vehicle gauge An outline drawing or specification of a notional vehicle, which prescribes maximum permissible vehicle and loading dimensions, certain suspension displacements, and certain curve overthrow limitations (for example, W6a).



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Structure An element of the infrastructure adjacent to, or crossing over, a railway track. So far as this document is concerned ‘structures’ include, but are not limited to:

a) train control and communications equipment (for example, signals)

b) station platforms

c) overhead line equipment supporting structures at earth potential, but excluding insulators

d) civil engineering structures such as retaining walls, tunnels and bridges

e) other isolated structures

f) temporary works.

Compare with ‘infrastructure’.

Structure gauge An outline drawing or specification, complete with application rules, defining a line inside which structures are not permitted to intrude.

Structure clearance The minimum calculated distance between a structure and the swept envelope of a specific type of rail vehicle passing at nominated speeds, taking account of appropriate track tolerances and accuracy of measurement.

Swept envelope A cross-sectional profile, taken at right angles to the track, enclosing all dynamic movements, static deflections and overthrows of all points along the surface of the vehicle, that can reasonably be expected to occur under the appropriate range of operating conditions as it sweeps past a theoretical track location. A family of swept envelopes is required to define a vehicle’s behaviour on a route.

The swept envelopes referred to within this document exclude the effects of track tolerance and rail sidewear previously included in kinematic envelopes developed under GM/RT2149 issue 1 or earlier documents.

Track fixity The degree to which a track is restrained from movement in any direction. Fixity can be different laterally and vertically, and can be asymmetric.

Track interval The distance between the running edges of the nearest rails of adjacent tracks measured 14 mm below the plane of the rails.

Upper sector The area above 1100 mm above the plane of the rails. See also ‘lower sector’.

B4 Principles This document supports HMRI Safety Principle 6:

‘There should be adequate clearances between trains on adjacent tracks and between trains and structures and fixed equipment to ensure safe passage.’



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Part C Control measures for clearances

C1 Introduction Part D of this document sets out requirements for calculating clearances.

The measures required to maintain the position of a track, relative to adjacent structures or tracks, depend on the size of the calculated clearance. Clearances are therefore categorised as ‘normal’, ‘reduced’ or ‘special reduced’ and control measures are defined for each clearance category.

GE/RT8270 permits gauging acceptance to be granted through a number of routes:

a) absolute gauging

b) comparative gauging (comparison with vehicles already cleared for a route)

c) gauging to standard vehicle gauges

d) hybrid gauging.

The method of categorising clearances depends on the route used to gain gauging acceptance for a particular vehicle.

C2 Categorisation of clearances

C2.1 Categorisation of clearances for absolute gauging Upper sector clearances to vehicles shall be categorised as normal, reduced or special reduced, in accordance with Table 1.

Speed (see section D1.5)

≤ 125 mph > 125 mph and ≤ 140 mph

Normal clearance ≥ 100 mm ≥ 100 mm

Reduced clearance ≥ 50 mm to < 100 mm Not applicable

Special reduced clearance

> 0 mm and < 50 mm > 0 mm and < 100 mm

Table 1: Upper sector clearances to structures and inter-vehicle Lower sector clearances to vehicles shall be categorised as normal, reduced or special reduced, in accordance with Table 2.

Speed (see section D1.5)

≤ 125 mph > 125 mph and ≤ 140 mph

Normal clearance ≥ 50 mm ≥ 50 mm

Reduced clearance ≥ 25 mm to < 50 mm Not applicable

Special reduced clearance

> 0 mm and < 25 mm > 0 mm and < 50 mm

Table 2: Lower sector clearances to structures



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C2.2 Categorisation of clearances for comparative gauging By definition, a vehicle subject to comparative gauging is contained within the swept envelopes of a chosen comparator vehicle. Clearances shall therefore be related to the chosen comparator vehicle, categorised in accordance with section C2.1.

C2.3 Categorisation of clearances to standard vehicle gauges The application rules for a particular vehicle gauge include the clearances appropriate to the vehicle gauge. Usually, only normal clearances are defined. However, it is permissible to define reduced and special reduced clearances.

Requirements for vehicle gauges are set out in Part J.

C2.4 Categorisation of clearances for hybrid gauging Clearances to particular parts of a vehicle shall be considered in accordance with the particular gauging route chosen for that part (comparative or absolute gauging). The smallest resulting clearance category shall then be used.

C3 Required control methods

C3.1 Control measures for normal clearances Special measures to maintain the position of the track, relative to adjacent structures and tracks, are not required at locations with normal clearances. However, the relative positions of structures and adjacent tracks shall be monitored and corrective action taken when necessary (see Part F).

C3.2 Control measures for reduced clearances Special measures to maintain the position of the track, relative to adjacent structures and tracks, are required at locations with reduced clearances. Such measures shall include:

a) keeping of site-specific records (see section C4)

b) monitoring the relative positions of structures and adjacent tracks at regular intervals (see Part F)

c) providing on-site information, which defines the relative positions of structures and adjacent tracks (see Part F).

The infrastructure controller shall have a process for authorising the use of reduced clearances. The authorisation shall be recorded, together with details of the special measures put in place to maintain the position of the track.

There are special compliance requirements associated with this section - see section B2.2.1.

C3.3 Control measures for special reduced clearances Use of special reduced clearances shall only be permitted in exceptional circumstances.

Special measures to maintain the position of the track, relative to adjacent structures and tracks, are required at locations with special reduced clearances. The required measures shall be identified on the basis of a risk assessment, demonstrating that risks have been reduced to as low as reasonably practicable.

The risk assessment shall take into consideration the following factors:

a) the vehicle(s) to which the clearance applies

b) the likely number of vehicles to which the clearance applies

c) the speed at which vehicles travel past structures and vehicles on adjacent tracks



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d) the size of the clearance

e) the arrangements for track maintenance such that clearance is maintained

f) the arrangements for monitoring and the frequency of monitoring

g) the track fixity

h) the likelihood of the track quality deteriorating to a value below that supplied to train operators for the purposes of calculating swept envelopes, in accordance with section D5

i) the level above the rails at which the clearance applies

j) the possible consequences of glancing contact

k) the exposure of the location to cross-winds.

The measures to maintain the position of the track shall include, but are not limited to, those required for reduced clearances (see section C3.2). Other measures (for example, increasing track fixity) are also likely to be required.

The infrastructure controller shall have a process for authorising the use of special reduced clearances. The authorisation shall be recorded together with details of the special measures put in place to maintain the position of the track.


C3.4 Review of special reduced clearances to confirm validity of risk assessments Special reduced clearances shall be reviewed to confirm the validity of risk assessments:

a) at six-year intervals

b) whenever there is reason to believe that the risk assessment has ceased to be valid (for example, because of a change to the type of vehicles or vehicle loads using the route, or a change to the speed of vehicles using the route).

C4 Records of clearances and control

measures Records of reduced and special reduced clearances shall include:

a) location (including identity of structure, identity of track and track mileage)

b) vehicle type(s) and speed(s) to which clearance applies

c) value of calculated clearance

d) written authority (date / person authorising)

e) details and date of measurement used for applying for gauging acceptance

f) frequency (time) of measurement

g) information on site datums

h) action to be taken when measured clearances are at variance to information on site datums

i) normal system of measurement



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j) any special enhanced track fixity or track maintenance requirements

k) risk assessment (special reduced clearances only)

l) any local circumstances that could affect clearances (such as exposure to high winds, embankment liable to subsidence).

Records of reduced and special reduced clearances shall be kept up-to-date. Records shall be retained until such time as normal clearances are achieved at the location to which the record applies.



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Part D Calculation of clearances

D1 Method of calculation

D1.1 Calculation of effective position of the track The maintained position of the track, relative to adjacent structures or tracks, shall be adjusted to allow for accuracy of measurement (see section D2) and track tolerances (see section D3), to arrive at an effective position of the track (as defined in section B3), relative to adjacent structures or tracks.

D1.2 Calculation of clearances for absolute and comparative gauging Clearances are the minimum calculated distance between structures and the appropriate vehicle swept envelope (see section D1.3) on track in its effective position, or between vehicle swept envelopes on tracks in their effective position.

The distance between passing vehicles shall be calculated by choosing the vehicle on the adjacent track which provides the least clearance for the particular track parameters.

D1.3 Selection of relevant swept envelopes for absolute and comparative gauging GM/RT2149 requires train operators to determine vehicle swept envelopes for vehicles, which includes:

a) the full permissible range of operating speeds and cant deficiencies for which the vehicle has been designed

b) the dynamic inputs of the track on the routes for which gauging acceptance is required

c) the range of design and maintenance tolerances for the vehicle and expected failure modes.

The relevant swept envelope shall be selected to suit the infrastructure at the location under consideration, taking the particular track parameters at the location into account (see Part E).

For comparative gauging, the relevant swept envelopes are those applicable to the comparator vehicle.

D1.4 Calculation of clearances to standard vehicle gauges Structure clearances are given by the minimum calculated distance between structures and the standard vehicle gauge on track in its effective position.

Passing clearances are given by the minimum calculated distance between the standard vehicle gauge and a vehicle on the adjacent track, on tracks in their effective position.

The distance between passing vehicles shall be calculated by choosing the vehicle on the adjacent track, defined by either a swept envelope or a standard vehicle gauge, which provides the least clearance for the particular track parameters.

D1.5 Speed to be used for calculation of clearances Where the permissible or enhanced permissible speed is higher than the maximum vehicle operating speed, it is permissible to use the maximum vehicle operating speed for the purpose of calculating clearances.



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D2 Measurement accuracy

Part E requires the accuracy with which the relative positions of track and adjacent structures or tracks are measured to be determined. This measurement accuracy shall be used when calculating the effective position of the track in accordance with section D1.1.

D3 Track tolerances D3.1 Track fixity The allowances for track tolerances to be made when calculating the effective position of the track in accordance with section D1.1 depend on the fixity of the track. For this purpose, track fixity is classified as follows:

a) high track fixity - track with fixity equivalent to slab track

b) medium track fixity - track with fixity equivalent to undisturbed glued ballast

c) low track fixity - track with fixity equivalent to normal ballasted track.

Track can have different fixities laterally and vertically and can exhibit asymmetric lateral fixity (for example, where track is strutted against a platform). Therefore, the track fixity appropriate to specific directions shall be used when calculating the effective position of the track.

D3.2 Allowances for track tolerance The allowances for track tolerances given in sections D3.3, D3.4, D3.5 and D3.6 shall be used when calculating the effective position of the track in accordance with section D1.1.

It is permissible for the allowances for track tolerances given in sections D3.3, D3.4, D3.5 and D3.6 to be reduced by 25% when calculating the clearance between a vehicle and vehicles on adjacent tracks.

The infrastructure controller shall determine the allowances for track tolerances to be used at specific locations where values exceeding those given in sections D3.3, D3.4, D3.5 and D3.6 can reasonably be expected (for example, on embankments subject to seasonal settlement).

D3.3 Allowance for variation in lateral alignment The allowances in Table 3 shall be applied as a change in the position of the track, applied in the plane of the rails.

Track fixity Allowance

High track fixity NIL

Medium track fixity +/- 15 mm

Low track fixity +/- 25 mm Table 3: Allowance for variation in lateral alignment



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D3.4 Allowance for variation in vertical alignment The allowances in Table 4 shall be applied as a change in the position of the track, applied perpendicularly to the plane of the rails.



Medium track fixity + 15 mm / - 10 mm

Low track fixity + 15 mm / - 10 mm Table 4: Allowance for variation in vertical alignment

D3.5 Allowance for variation in cross-level The allowances in Table 5 shall be applied as an increase or decrease in cant, measured relative to the low rail.



Medium track fixity +/- 7.5 mm

Low track fixity +/- 10 mm Table 5: Allowance for variation in cross-level

D3.6 Allowance for sidewear The allowances in Table 6 shall be applied as a change in the position of the track, applied in the plane of the rails, towards the side of curved track that exhibits, or has in the past exhibited, sidewear.

Permissible speed Allowance

≤ 125 mph 4.5 mm

> 125 mph 3 mm Table 6: Allowance for sidewear

D4 Adjustment for cross-wind

Train operators are required by GM/RT2149 to determine the swept envelopes of vehicles for cross wind speeds of 0 m/s and 35 m/s, and any higher limit for particularly exposed routes identified by the infrastructure controller.

The infrastructure controller shall identify exposed routes and the cross wind speed, above 35 m/s, for which additional swept envelopes are required.

The effect of wind on clearances, taking into consideration the swept envelopes required by GM/RT2149, shall be assessed on exposed routes where reduced and special reduced structure and passing clearances are proposed.

D5 Track quality data GM/RT2149 requires vehicle swept envelopes to be determined for ‘the range of ... track quality appropriate to the route(s) for which gauging acceptance is required’.

The infrastructure controller shall specify, for appropriate speed bands, generic track quality data to be used for determining vehicle swept envelopes in accordance with GM/RT2149.



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The generic track quality data shall be such that, at any given time, at least 90% of the track within the speed band on Railtrack controlled infrastructure is of a higher quality than the generic data.

The infrastructure controller shall consult with train operators and take their views into account when determining the format of the track quality data to be used for this purpose (for example, the track roughness spectrum of a representative length of track).

It is permissible for the infrastructure controller to maintain sections of track to a different standard than that to which the generic track quality data applies, provided the requirements mandated in Railway Group Standards are met. Sections of track maintained to different standards shall be identified and track quality data applicable to the identified sections of track shall be specified.




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Part E Determining the relative positions of tracks and structures

E1 Need for measurement

E1.1 Where measurements are required To permit clearances to be calculated, it is necessary to determine the relative positions of tracks and structures. Measurements to determine the relative positions of tracks and structures shall therefore be taken and recorded where:

a) clearances to structures in the upper sector are likely to be less than twice the normal clearance defined in section C2

b) structures are likely to be within 200 mm of the lower sector structure gauge shown in Appendix 1

c) passing clearances between vehicles are likely to be less than twice the normal clearance defined in section C2.

E1.2 Relating measurements to the maintained position of the track All measurements shall be related to the maintained position of the track (that is, the position in which the track should be placed during maintenance).

Where the maintained position of the track has not been established by design, it is permissible to take the actual track position at the time of measurement as the maintained position, provided the track does not contain alignment faults.

E2 Detailed requirements for

measurements E2.1 Determination of the maintained position of the track E2.1.1 Data to be recorded The following data shall be recorded at regular intervals at the location under consideration, and for 10 m beyond:

a) measurements to define horizontal track alignment, including curve radius, cant, transitions and cant gradients

b) measurements to define track vertical alignment, including gradients and radii of vertical curves

c) measurements to define track intervals

d) whether any rails on curves are subject to sidewear

e) the lateral and vertical track fixity

f) the permissible or enhanced permissible speed.

E2.1.2 Spatial intervals between measurements The spatial intervals between measurements shall take into account:

a) the minimum assessed clearances and vehicles to which they apply

b) the horizontal curvature of the track

c) the relative levels and cants of the adjacent tracks.



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E2.2 Determination of the profile of structures The profile of structures relative to the track shall be established by measurement.

The number of points at which measurements are taken to define the profile of a structure shall take into account:

a) the closeness of the structure to the track

b) the curvature of the surface of the structure

c) the irregularity of the surface of the structure

d) the curvature of the track, horizontally and vertically.

E3 Accuracy of measurement

The accuracy with which the relative positions of track and adjacent structures or tracks are measured shall be determined, taking into account:

a) the accuracy of the measuring system

b) any likely human error

c) the spatial intervals between measurements, both longitudinally and laterally to the track.

This information is needed to meet the requirements of Part D.

E4 Records of the relative positions of

tracks and structures Records of the relative positions of tracks and structures shall be kept for all locations where the circumstances listed in section E1.1 apply.

The records shall be related to the maintained position of the track (see section E1.2).

The records shall permit clearances to be calculated in accordance with Part D and clearances to be monitored in accordance with Part F.

The records shall include as a minimum:

a) the data relating to the maintained position of the track required by section E2.1

b) the profiles of structures determined in accordance with section E2.2

c) the accuracy of measurement determined in accordance with section E3.

Records of relative positions of tracks and structures shall be kept up-to-date. Records shall be retained until such time as the circumstances set out in section E1.1 cease to apply at the location to which the record applies.

E5 Reassessment of the relative positions of

tracks and structures E5.1 Periodic assessment of continuing validity of measurements The continuing validity of the measurements taken to determine the relative positions of tracks and structures shall be assessed periodically.



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The frequency of assessment shall be determined taking into account:

a) whether clearances are normal, reduced or special reduced

b) whether on-site information, defining the relative positions of track and structures, is provided

c) the level of monitoring undertaken in accordance with Part F of this document

d) maintenance activities at the location

e) other factors which might cause the measurement to become invalid.

E5.2 Assessment following works likely to affect clearances The continuing validity of the measurements taken to determine the relative positions of tracks and structures shall also be assessed following any works, other than routine maintenance and repairs, likely to affect clearances at a location. Such works include, but are not limited to:

a) installation of new tracks or structures

b) erection of any temporary works at a structure

c) renewal of the track or structures

d) adjustment of platform coping stones or their equivalents

e) realignment of the track (that is, adoption of a new maintained position of the track)

f) maintenance work involving significant track disturbance.

E5.3 Assessment following disturbance to the infrastructure The continuing validity of the measurements taken to determine the relative positions of tracks and structures shall also be assessed following any disturbance to the infrastructure at a location likely to affect clearances. Such disturbances include, but are not limited to:

a) movement of earthworks supporting the track

b) signs of distress or movement at a structure.

E5.4 Requirement for re-measurement Re-measurement shall be undertaken if an assessment shows that there is reason to doubt the continuing validity of the recorded measurements.



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Part F Monitoring and maintaining the relative positions of tracks and structures

F1 Need for monitoring Part C of this document requires the relative positions of structures and adjacent tracks to be monitored and corrective action taken when necessary. Detailed requirements for monitoring and maintaining the relative positions of tracks and structures are set out in sections F2 to F5.

F2 Selection of monitoring systems

The following shall be considered when selecting systems to monitor the position of tracks and structures:

a) competence requirements of the system

b) accuracy of the system proposed

c) safety of people using the system

d) ease of access to the infrastructure

e) reliability of equipment

f) auditability.

Monitoring systems include measurement to fixed datums, on track gauging trains, hand held gauges and portable electronic (laser) systems.

F3 Frequency of monitoring

The infrastructure shall be monitored at a frequency consistent with the maintenance of the clearance / risk regime for the particular structure or location (for example, more frequent monitoring is required where reduced or special reduced clearances are used).

In determining the frequency of monitoring, it shall be assumed (in the absence of actual track movement data) that the allowance for variation in lateral alignment for the appropriate track fixity, given in section D3.3, applies cumulatively for each year since the relative positions of track and adjacent structures or tracks were last measured. It is permissible to make a less conservative assumption where this can be supported by actual track movement data.

F4 On-site information defining the relative

positions of tracks and structures

F4.1 Provision of fixed datums Fixed datums shall be provided at all locations where reduced and special reduced structure clearances apply, or where structures are likely to be within 200 mm of the lower sector structure gauge shown in Appendix 1.

Requirements for datums giving the maintained position of tracks at electrification masts and other contact wire supports on overhead electrified lines, are set out in GC/RT5021. Datums could also be needed to meet the requirements set out in GC/RT5021 for monitoring track geometry where trains are permitted to travel at enhanced permissible speeds.



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F4.2 Information to be provided on fixed datums The following information shall be provided on fixed datums:

a) a unique reference identity

b) the identity of the track to which it refers

c) the distance (horizontally) from the datum to the maintained position of the running edge of the adjacent rail (with no allowance for sidewear)

d) the maintained height of the adjacent rail in relation to the datum

e) the maintained cant.


F4.3 Marking track intervals Information about track intervals shall be provided on site for reduced passing clearances, unless both tracks are referenced to a structure by a fixed datum.

Information about track intervals shall be provided on site in all locations with special reduced passing clearances.

Information shall be provided in a way that ensures its purpose is clear (for example, by plates placed on sleeper ends or clipped to rails).


F4.4 Information to be provided for marking track intervals The following information shall be provided for marking track intervals:

a) a unique reference identity

b) the identity of the reference rail

c) the distance (horizontally) between the maintained position of the running edges of the nearest rails of the adjacent tracks

d) the maintained height of the reference rail above / below the nearest rail of the adjacent track

e) the maintained cant of both tracks.


F4.5 Spatial intervals for datums and marking of track intervals When required by sections F4.1 and F4.3, fixed datums and marking of track intervals shall be provided at intervals not greater than those shown in Table 7, measured along the track.



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Location Horizontal radius Maximum interval

Through platforms < 2000 m 10 m

Through platforms ≥ 2000 m 20 m

Elsewhere < 2000 m 20 m

Elsewhere ≥ 2000 m 40 m Table 7: Maximum intervals for fixed datums and marking of track intervals


F4.6 Checking of fixed datums and marking of track intervals Fixed datums and marking of track intervals shall be checked periodically to determine that they continue to be in place and the information remains valid.

The checks shall be carried out at intervals of not more than two years. At locations with high track fixity, it is permissible to increase the interval to six years.

Additional checks shall be carried out whenever work is undertaken affecting platform coping stones or their equivalents.


F5 Actions to correct the relative positions of

tracks and structures F5.1 Procedure identifying actions required A procedure shall be in place that identifies the actions required when:

a) the relative positions of tracks and structures differ from those recorded in accordance with section E4

b) measurements vary from the dimensions shown on site (see section F4).

F5.2 Actions required by the procedure The actions required by the procedure shall vary according to:

a) the amount by which the measurements differ from those recorded in accordance with section E4 or from the dimensions shown on site

b) the type of clearance present (normal, reduced or special reduced)

c) the number of vehicles passing

d) permissible or enhanced permissible speed.

The procedure shall clearly state the timescale for action. It shall also state the circumstances in which a speed restriction is to be imposed or the line blocked.

The actions required by the procedure shall be implemented.

If it is intended to acknowledge a new maintained position of the track, the relative positions of tracks and structures shall be reassessed, as required by section E5.



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Part G Requirements for new, altered and temporary infrastructure

G1 Minimum upper sector clearances for

new infrastructure G1.1 Requirement for normal clearances New infrastructure (as defined in section B3) shall be designed to provide at least normal clearances (as defined in section C2) to all types of rolling stock that use the route or can reasonably be foreseen to use the route.

The required clearances shall be calculated in accordance with Part D of this document.

G1.2 Additional clearances at vehicle window level The following clearances shall be provided at the level of opening vehicle windows (normally between 2000 mm and 3000 mm above the plane of the rails):

a) 450 mm where vehicles operate with opening windows allowing passengers to lean out

b) 250 mm where vehicles operate with opening windows for the use of train crew.

GM/RT2456 requires passenger door windows that are capable of being opened (drop lights) to be locked so that they can only be opened manually by train crew. This requirement is to be implemented by 31 December 2005 for all vehicles that are intended to remain in passenger use after 31 December 2007.

G2 Lower sector structure gauge for new

infrastructure New structures shall not intrude inside the structure gauge set out in Appendix 1.

New track shall be positioned to ensure adjacent structures do not intrude inside the structure gauge set out in Appendix 1.

When designing new infrastructure, allowance shall be made for construction tolerances to ensure these requirements are met once the infrastructure has been built.

Exceptionally, short lengths of new extensions to platforms are permitted to intrude inside the structure gauge where this is necessary to allow the extension to be blended into the existing platform.

Station platforms necessarily approach closely to trains to enable safe boarding and alighting. Additional requirements for platforms, including stepping distances, are set out in GC/RT5161.

G3 Track intervals for new infrastructure

For each section of track the infrastructure controller shall determine track intervals to be used for new infrastructure, taking into account:

a) the requirement to provide normal clearances, as set out in section G1.1

b) where necessary, the requirement to provide additional clearances for opening windows, as set out in section G1.2



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c) if required, the space needed for trackside equipment (for example, signals and speed signs).

G4 Alterations to existing infrastructure

G4.1 Alterations other than to permit the passage of larger rail vehicles When existing infrastructure is altered for reasons other than to permit the passage of larger rail vehicles, the alteration shall be designed so that:

a) normal clearances do not become reduced or special reduced clearances

b) any reduced or special reduced clearances are not made smaller.

G4.2 Alterations to permit the passage of larger rail vehicles When existing infrastructure is altered to permit the passage of larger rail vehicles, it is permissible for the alteration to be limited to that which is just sufficient to allow the passage of the larger vehicles, provided the control measures appropriate to the resulting clearance category (for example, special reduced clearance) are implemented in accordance with Part C.

G4.3 Complete rebuilding of existing structures When an existing structure is to be completely demolished and rebuilt, the requirements for new infrastructure set out in sections G1 to G3 shall be applied to the rebuilt infrastructure, so far as it is practicable to do so within the constraints of the site. Where this is not practicable, control measures appropriate to the resulting clearance category (for example, reduced clearance) shall be implemented in accordance with Part C.

G5 Temporary infrastructure

The requirements for new infrastructure set out in sections G1 to G3 shall be applied to temporary infrastructure (for example, scaffolding or temporary alignments during staged works), so far as it is practicable to do so within the constraints of the site. Where these requirements cannot be met, consideration shall be given to the need for mitigation measures. The mitigation measures considered, and the mitigation measures adopted, shall be documented.

G6 Requirements of HM Railway Inspectorate

Dispensation from HM Railway Inspectorate could be required when the guidance contained in ‘Railway Safety Principles and Guidance’ is not satisfied.



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Part H Exceptional loads

H1 Gauging conditions for passage of

exceptional loads GO/RT3407 requires the infrastructure controller to determine the gauging and route availability conditions for the passage of exceptional loads. In determining these conditions for out-of-gauge loads, consideration shall be given to:

a) proposed carrying vehicle

b) dimensions of the load

c) any eccentricity of the load

d) any dynamic behaviour of the load

e) required routing.



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Part J Standard vehicle gauges

J1 Requirement to have standard vehicle gauges

GE/RT8270 permits gauging acceptance to be granted on the basis of standard vehicle gauges. The infrastructure controller shall define the standard vehicle gauges to be used for this purpose.

Standard vehicle gauges shall be defined in the following categories, and additional gauges added as circumstances require:

a) gauges for freight rolling stock

b) gauges for passenger vehicles

c) locomotive gauges.

Standard vehicle gauges shall be consistent with the lower sector structure gauge given in Appendix 1.

The infrastructure controller shall have a process for consulting train operators about the range of vehicle gauges required.


J2 Application rules for standard vehicle gauges

The rules necessary to apply a vehicle gauge shall be fully defined.

The application rules shall include the clearances appropriate to the vehicle gauge. Usually, only ‘normal’ clearances are defined. However, it is permissible to define ‘reduced’ and ‘special reduced’ clearances.

The ‘normal’, ‘reduced’ and ‘special reduced’ clearances defined in the application rules shall not be less than those set out in section C2.

The ‘normal’, ‘reduced’ and ‘special reduced’ clearances defined in the application rules shall be consistent with the control methods required by section C3.

Before introducing a new vehicle gauge, the infrastructure controller shall consult train operators about the application rules proposed for the gauge.


J3 Availability of sections of track for

standard vehicle gauges The infrastructure controller shall have a procedure for determining the availability of sections of track for standard vehicle gauges.

Where a route is declared as accepting a particular gauge, the clearances associated with that gauge shall be maintained.




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Part K Data to be provided to Railway Group members and their suppliers The information referred to in this part of the document (Part K) relates only to the scope of this document. To fully describe the infrastructure, other information is also required.

K1 Requirement to provide information

The infrastructure controller shall keep, maintain and make available to Railway Group members and their suppliers the information listed below, when legitimately required for the execution of their business.

a) locations with reduced and special reduced clearances, and the vehicle type(s) to which the clearances apply (see section C4)

b) exposed routes where wind speeds above 35 m/s are likely to be experienced (see section D4)

c) generic track quality data for different speed bands to be used for determining vehicle swept envelopes in accordance with GM/RT2149 (see section D5)

d) locations of sections of track maintained to different standards than that to which the generic track quality data applies, together with the specific track quality data applicable to the identified sections of track (see section D5)

e) records of the relative positions of tracks and structures, for all locations where the circumstances listed in section E1.1 apply (see section E4)

f) the standard vehicle gauges that are permitted to be used as a basis for granting gauging acceptance (see section J1)

g) the availability of sections of track in terms of standard vehicle gauges (see section J3)

h) sections of track carrying specific types of vehicle requiring the application of special cases for the lower sector gauge (see Appendix 1)

i) information concerning locations with temporary non-compliances or derogations against the requirements of this document.


K2 Processes for providing information

The infrastructure controller shall publish the processes by which the information required by this part of the document (Part K) is to be provided, including:

a) a point of contact for the supply of information

b) a schedule of information that can be provided on application, and its format (for example, on CD)

c) a schedule of information available for reference only, and where it can be viewed

d) the notice period required for provision of information

e) details of any publications, in the form of catalogues or bulletins, which the infrastructure controller intends to circulate to Railway Group members and their suppliers.



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Appendix 1 Lower sector structure gauge (This content of this appendix is mandatory)

Plane of Rails

110

X

Y = 915

140

240

64

38

40

1100 Centre line of

track

270

25 40

54

Area reserved for items intended to come in close proximity to trains (for example, conductor rails and AWS magnets)

Area available for fixed infrastructure

Figure 1: Lower sector structure gauge

1.1 Notes All lines are parallel to, or at right angles to, the plane of rail (see figure 2).

All dimensions are measured relative to the maintained position of the track, as defined in section B3.

All dimensions are in mm.

X is measured from the running edge of the nearest rail at a position 14 mm below the head of rail.

Y is measured perpendicular to the plane of the rails.

Where applied cant is more than 130 mm at a location, Y shall be reduced by 10 mm on the inside of curved track.

Where sidewear is expected on curves an increase in dimension X shall be considered in line with values in section D3.6.



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Figure 2: Example of lower sector structure gauge applied to a standard platform

1.2 Values of ‘X’ for the standard case

For straight track and curved track with a radius greater than or equal to 360 m:

X = 730

For curved track with a radius less than 360 m but greater than or equal to 160 m:

X = 658 + (26000 / R)

Where R is the curve radius in metres and X is in mm.

The formula quoted gives the following results for selected radii:

Radius (m)

X (mm)

360 730

300 745

250 762

200 788

160 821

1.3 Values of ‘X’ for special cases

1.3.1 Class 373 (Eurostar) routes For straight track and curved track with a radius greater than or equal to 360 m:

X = 760

For curved track with a radius less than 360 m but greater than or equal to 160 m:

X = 688 + (26000 / R)




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Radius (m)

X (mm)

360 760

300 775

250 792

200 818

160 851

1.3.2 2.6 m wide container routes For straight track and curved track with a radius greater than or equal to 360 m (for the outside of curved track) or 500 m (for the inside of curved track):

X = 730

For the outside of curved track with a radius less than 360 m but greater than or equal to 160 m:

X = 658 + (26000 / R) [as the standard case]

For the inside of curved track with a radius less than 500 m but greater than or equal to 160 m:

X = 664 + (33000 / R)



Radius (m)

X (mm)

500 730

360 756

300 774

250 796

200 829

160 870

1.3.3 Non-standard platforms required by special cases The special cases permitted by sections 1.3.1 and 1.3.2 require non-standard platforms. Where such special cases are introduced onto a route, the requirements set out in GE/RT8270 are applicable.

1.4 Structures adjacent to curves with radii less

than 160 m Structures adjacent to curves with radii less than 160 m shall be subject to a special assessment.



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References Railway Group Standards and other Railway Group Documents

GA/RT6001 Railway Group Standards Change Procedures

GA/RT6004 Temporary Non-Compliance with Railway Group Standards

GA/RT6006 Derogations from Railway Group Standards

GC/RT5021 Track System Requirements

GC/RT5161 Station Design and Maintenance Requirements (planned to be superseded by GI/RT7016 for requirements relating to platforms)

GC/RT5203 Infrastructure Requirements for Personal Safety in Respect of Clearances and Access

GE/RT8019 Tilting Trains: Controlling Tilt Systems to Maintain Clearances

GE/RT8025 Electrical Protective Provisions for Electrified Lines

GE/RT8047 Reporting of Safety Related Information

GE/RT8270 Route Acceptance of Rail Vehicles Including Changes in Operation or Infrastructure

GM/RT1403 Use of Plant and Work Equipment

GM/RT2149 Requirements for Defining and Maintaining the Size of Railway Vehicles

GM/RT2456 Structural requirements for windscreens and windows on railway vehicles

GO/RT3407 Train Operation - Exceptional Load Documentation

The Catalogue of Railway Group Standards and the Railway Group Standards CD-ROM give the current issue number and status of documents published by Railway Safety.

Other References HS(G)153/1 HMRI Railway Safety Principles and Guidance
