A Guide to Permanent Way Design

by Paul King

Contents Page No

Introduction 2

Horizontal Design a. Basic Elements 3 b. Cant and Deficiency 5 c. Transitions 8

Vertical Design a. Terminology 11 b. Constraints 11 c. Design Methods 12 d. Design for canted track 13 e. Calculation example 14

Switch and Crossing Geometry a. Basic elements 16 b. Switch details 17 c. Crossing details 18 d. Turnout types 19 e. Speed characteristics 20 f. Design guidelines 20

Track Layouts 22

Clearances and Vehicle Envelopes 25

Hallade Design 35

Survey Requirements a. S&C 43 b Plain Line 44

Author – Paul King Date – September 2011

- 1 – Copyright – P.J. King A Guide to Permanent Way Design

Introduction

This booklet is the combination of a series of design lectures given by me over the past ten years. The intention was to provide the beginner / novice with simple guidelines to give an appreciation of the basics elements of track design starting with horizontal and vertical design. These are the basic elements upon which track design is built. Sections are also included on switch and crossing geometry, clearances and track survey requirements. Network standards have been referenced where appropriate. It should be noted that these do change from time to time.

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Track Geometry

Horizontal Design – Plain Line a. Basic Elements i. Elements of STRAIGHTS and CIRCULAR CURVES Design They can be linked by spirals known as TRANSITIONS. Transitions can also link different curves. They are not elements but LINKS.

ii. Definitions STRAIGHT- Shortest distance between 2 points, line of constant bearing.

CIRCULAR CURVE - Line that is a fixed distance (radius) from a point (circle centre).

TRANSITION - Curve of constantly changing radius – a spiral.

Diagram 1 – Low speed layouts – Typically sidings

(Element) (Element) Tangent Point

Diagram 2 – Main Line arrangement

(Element)

Tangent Point (Link)

(Element)

Note – Tangent point is where 2 elements or an element and a link meet.

- 3 – Copyright – P.J. King A Guide to Permanent Way Design iii. Theory

Why have straights? Easy to design, set out and maintain Constant force on track from train wheels Shortest-quickest – distance to travel

Why have Circular curves? Constant force from train wheels which can be offset by cant (see later) Easy to design, set out and maintain

Transitions – They avoid an instant change of radius, which What are they for? would be very noticeable at high speed inside the train – see rules in following section. Provide area for cant (super elevation) –– to be built up. See following section for details.

Transitions – What shape? This depends on design method used but all are very similar 1. Hallade – Cubic Parabolic 2. Mx or BRT – Clothoid or Bloss

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b. Cant and Deficiency Rails inclined at 1:20 (to match train wheels) i. Straight Track towards track centre Diagram 3

Cant = Difference in rail levels

Note – Track gauge (G) = 1435mm or 1432mm for older Cen56 designs (Distance between inside edges – running edges - of rail)

Other Typical Dimensions Depth of Track Construction (D) = 365mm Length of Sleeper (L) = 2500mm – 2600mm

ii. Curved Track Diagram 4

W - Weight of vehicle F - Acceleration force R – Resultant of W&F E – Cant/mm

E = 11.82V2 For R = W+F R 1

R = Radius in metres V = Speed in Kph - E = Equilibrium cant in millimetres – Train wheels exert no sideways force on the rails

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Generally a cant less than E is applied because:

 E is designed for the maximum speed and not all trains run at this speed  Applying a lower cant will result in a force between the high wheel and the rail – this ‘guides’ the train around the curve  Reduces contact fatigue

To apply a cant less than the equilibrium will result in a deficiency. This value is called the ‘CANT DEFICIENCY’ (D). (It creates an outward force on the high rail (Y)). The designed cant (Ea) and deficiency total the equilibrium cant:

Ea + D = E

iii. Limiting Values Non tilting trains

These are shown in Railtrack standard NR/L2/TRK/2049 – Track Design Handbook (TDH) – pages B2.1 – B2.4. The cant deficiency (for conventional trains) should not normally exceed 60% of the applied cant on jointed track or 73% of this figure for continuously welded track (CWR). Exceptionally these figures may be increased to 73.3% and 100% respectively. This can be summarised:

Jointed Track - Dmax = 0.6Ea = 0.375E Dexp = 0.733Ea =0.423E

CWR Track - Dmax = 0.73Ea = 0.422E Dexp = Ea =0.5E

The above maximum values apply to a general cross section of lines. High speed lines should be designed such that the deficiency is a minumum of half the cant:

D = 0.5Ea = 0.667E

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The maximum values of cant and deficiency are shown in the TDH on Pages B2.1 – 2.3, these can be summarised:

Jointed Track - Dmax = 90mm Dexp = 110mm Emax = 150mm Eexp = 180mm

CWR Track - Dmax = 110mm Dexp = 150mm Emax = 150mm Eexp = 180mm

The maximum and not exceptional figures should be generally used. iii. Limiting Values Tilting trains

Tilting trains can run at what’s known as Enhanced Permissible Speed (EPS) – conventional trains run at Permissible Speeds (PS). PS characteristics have generally been shown throughout this paper. At EPS speeds the maximum permitted cant deficiency is 265mm and this depends on the radius. For full EPS data refer to the TDH on Page B2.2.

iv. Calculation Example

Determine Ea for the following:

V = 50 mph (x by 1.609 for Kph) R = 500m If D = 0.5Ea

Using equation 1 E = 11.82 v2/R

E = 11.82 x (50 x1.609)2 500

E = 153.00mm

Ea = 0.667E = 102mm

In practical terms cant is set in 5mm increments therefore:

Ea is set as 100mm

D = 153 – 100 = 53mm

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As previously defined these are links between curved and straight tracks (or curve to curve), they are a form of spiral which smoothly forms the link.

Diagram 5

(Element) (Link) Tangent Point

(Element)

Transitions are needed on all alignments except:

 Sidings  Low speed areas such as stations/depots  Compound curves of similar radii

Where cant is applied to a curve this is built up at a constant rate through the transition. (Transitions are usually marked on site showing the cant at 5mm steps, the limits of the transition are also marked.)

i. Design Requirements

Having determined the cant required for the circular curve an appropriate length of transition needs to be designed. This is done by using limiting values laid down in the Track Design Handbook (TDH). These are shown on page B2.1. The two critical factors are:

 Cant gradient (Egrad)

Egrad = 1 in Transition length (TL)/Ea 2

 Rates of change (RoC) of cant (Ea) and cant deficiency(D)

RoC = (Ea or D) x V (mm/second) 3.6 x TL 3

TL = Transition length in metres

If the transition links two curves, Ea = Ea1– Ea2 for curves 1 & 2. Similarly D = D1 – D2.

- 8 – Copyright – P.J. King A Guide to Permanent Way Design ii. Limiting Values

TDH page B2.1

 Cant gradient = 1 in 400 – 1 in 1500 ( normal limits)

 Rate of change Ea or D = 35mm/sec desirable 55mm/sec maxiumum 70mm/sec exception maximum

The above values for rates of change do not apply to tilting trains, these are 35mm/s, 110mm/s and 150mm/s respectively from the TDH page B2.3.

A practible arrangement is to fix the change of cant at 1mm/ sleeper. This gives values of between 1:600 and 1:760.

iii. Calculation example

TL to be determined from the following values:

V = 50mph R = 500m E = 100mm

From equation 3 using a rate of change of cant of 35mm/sec we can calculate TL using either Ea or D whichever is greater. From the example worker in section 2 it can be seen that Ea is the critical factor here.

35 = Ea x V 3.6 x TL

TL = Ea x V 35 x 3.6

= 100 x (50 x 1.609) 35 x 3.6

TL = 63.84m

It would be usual to round this to the nearest 5m to make it a ‘tidy’ length.

Therefore TL = 65m

Check this for gradient limits using equation 2

Egrad = 1 in 65/0.1 ( units in m)

Egrad = 1 in 650

This is within the limits as outlined above and is acceptable.

- 9 – Copyright – P.J. King A Guide to Permanent Way Design iv. Additional Information i) For curve equations – See TDH pages C2.1 – C2.5

v. Summary a. The elements in horizontal alignment are straights and circular curves, they can be linked with transitions. b. The applied cant is a factor of the square of the speed divided by the track radius. c. Cant is always designed with a deficiency. d. Transitions are fixed by their length and are determined by the rate of change of cant or deficiency and cant gradient.

vi. References a. Design Methods – MX Rail Bentley Railtrack Hallade – See section 1F b. Standards

Factors concerning speed, cant and transitions are shown in the TDH section B. For mathematical formulae regarding curves and transitions see section C of this document.

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Vertical Profile Design

To accompany any horizontal track design a vertical profile will be needed. Apart from a new track this will be a smoothing out of the existing profile.

There are two basic elements: Straight Gradient Vertical Curve - usually link gradients IP1 a. Terminology

G1 VC1 G2

TP2 TP3

TP1

TP4 G1 & G2 - Straight gradients TP1 – 4 - Tangent points at the ends of G1 & G2 IP1 – Intersection Point of G1 & G2 VC1 – Vertical Curve

Vertical curves are of the cubic parabola form. b. Constraints

The vertical profile must tie-in to the existing track with zero lift and matching gradients (+2mm/m) at the start and end of the design.

Gradients should not be steeper than 1 in 100.

G h

Gradient = 1 in L/h OR h/L x 100%

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The exceptions to these limits are:

Station platforms- 1 in 500 max  Stabling sidings – 1 in 500 max – should fall away from running lines  Approaches to signals – Seek guidance from signalling engineer

i. Gradients should be at least 30m long

ii. Vertical Curves are determined by their length and/or radius. They should be at least 20m long and have a radius appropriate to the design line speed. The speed/radius limitations are shown in the TDH page B4.1.It is possible to connect gradients without using vertical curves if they are of a similar gradient with less than 0.02% difference. These criteria are again shown in the TDH.

iii. The design values regarding vertical curves should be used in the following order:

 Normal values  Maximum values  Exceptional values – Engineering judgement to be used. Risk assessment to be undertaken.

c. Design Methods

G2 G3

G1 B A VC2

VC1 Existing Track Profile

From the survey and track profile it should be possible to identify areas where gradients can be fitted. These should be done to fit in with the existing track as closely as possible. This is essential when considering areas with overhead line equipment (OHLE) where any track adjustment will effect the height of the contact wire.

As a general rule try to keep lifting/lowering to +/- 50mm. (It may be necessary to seek guidance from the OHLE engineer.) The limits of the design must tie in to the existing levels at A and B.

If required add curves VC1 & VC2 to complete the design.

Finally carry out the following checks:

i. Gradients (G) are at least 30m long and are not steeper than in b.1 ii Vertical curves (VC) are at least 20m long and comply with the limitations shown in the TDH.

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iii Areas outside the limits of the track renewals are not designed to be lowered. (Lifting the track is a relatively simple ‘tamping’ operation. Lowering usually requires the track to be removed, ballast re-graded and the track relayed.)

d. Design for canted track

DR LD

DR E

DR – Datum Rail LD – Level difference between tracks – in plane of rails E - Cant

On canted track the low rail is taken as the Datum Rail - the vertical profile design is applied to this rail and the cant is applied to fix the gauge rail (high rail).

On pairs of tracks, with 1970mm interval, it is necessary to limit the level difference between the tracks to preserve the ballast shoulders at the sleeper ends. This figure is not laid down in standards but a good general guideline is +/- 150mm. This should be borne in mind when carrying out the design. If these tracks are linked, i.e. with switches and crossings, the two tracks must be co-planar – no level difference (as shown above).

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B e. Calculation Example

G1 VC1 G2

Chainage/m Level/m C A - 25 99.106 B - 150 100.987 C - 275 99.951

VMAX – 50mph

From the design table and guidelines in the TDH on pages B4.1- 4.2 calculate:

i) Length and slope of gradients ii) Radius and length of vertical curve

From equation 4 determine gradients G1 and G2.

G1 = h/L x 100 %

= (100.987 – 99.106) x 100 (150-25)

= 1.881 x 100 125

G1 = 1.5048 %

Similarly G2 = 1.036 x 100 125

G2 = -0.8288 % (negative gradient)

From page B4.2 equation 2.7 – Radius R = 100 x L G

G = G1 – G2

Using the chart on page B4.1 the radius for normal design limits required for 50mph = 2.3km.

Therefore:

Using equation 2.7 – L = R xG 100

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L = 2300 x (1.5048 + 0.8288) 100

L = 53.673

Therefore:

Length of G1 = 125 – 53.673/2 (vertical curve is taken to be centred about the IP at B – see TDH page B4.2 for theory)

= 98.164m

G1 = A gradient of 1.5048 % 98.164m in length

Similarly:

G2 = A gradient of - 0.8288 % 98.164 in length

f. Summary of Vertical Design i. Vertical designs are comprised of 2 elements – gradients and vertical curves ii. Design must tie in to the existing with zero lift and similar gradient (+/- 2mm/m) iii. Gradients and vertical curves should comply with limits described in section i). iv. Track adjustments are minimised v. No lowering outside areas being relayed

g. References

TDH pages B4.1 – 4.2

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Switch and Crossing Geometry a. Basic Elements

Check Rail

Rs Rt

Switch Crossing

Rs = Switch Curve (radius in metres) Rt = Turnout Curve - radius to or through crossing

The above diagram shows a typical arrangement known as a ‘TURNOUT’. This arrangement consists of two basic elements – a SWITCH and a CROSSING (S&C). (The check rails are usually required with the crossing.) These items are arranged to suit operating requirements which are usually determined by speed.

There are now two types of S&C in general use:

 113A Vertical  Cen60

The latter type is a recent development associated with the new, larger UIC60 rail section. The fundamental principles governing these layouts are however the same. Both have a series of switches and crossings which can be combined to accommodate a variety of turnouts. The 113A layouts have rails which are vertical and not at the plain line inclination of 1 in 20 – the CEN60 layouts use inclined rails.

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b. Switch Details

Heel Fronts Switch Rail

Straight Main Line Switch Radius

Toe Stock Rail

The radii and speed characteristics for Cen60 and Cen56 (113A) switches are shown in the TDH on pages A1.3 and A1.4. The lowest speed switches are C (Cen60), or Av (Cen56). They have the tightest radii. It should be noted that Av (v = vertical) switches are not generally used.

The geometry between the switch radius and the toe differs with the two designs. The 113A switches have a planing curve which meets the stock rail at the ‘Entry Angle’. CEN60 layouts are theoretically tangential – in reality a short length of straight is introduced – see details in the TDH.

- 17 – Copyright – P.J. King A Guide to Permanent Way Design c. Crossing Details

Wing Fronts

a c

Intersection Point Nose

Vee Rail Crossing Angle, A = 2 x a

- a = tan –1 c/b

- A = 2 tan-1 c/b

Note - tan-1 c/b = angle whose tangent is c/b

- N value for the crossing = 1 / (2 x tan a)

It is not possible to machine the crossing nose to a point, ie where the intersection point (IP) is. It is set to a width of 16mm. So in practical terms the distance from the nose to the IP = 16 x N. N being the crossing angle. For details of crossing angles see the TDH pages C3.1 and C3.2.

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Main Line

Rs Rt Rs Rt Turnout Transition Straight

Rs = Switch Radius Rt = Turnout Radius i) Transitioned Turnout ii) Circular Curve Turnout

Type i) is used where the turnout alignment keeps close to, or runs parallel to the Main Line. The transition avoids an instant change in radius where the track is reversing and is required in crossovers (see below) when the speed exceeds 25mph. The circular curve arrangement is used where the tracks continue to diverge and a curve is necessary beyond the crossing.

Turnout

1970mm Interval

iii) Typical Crossover

The crossover is essentially a combination of two turnouts. These are almost always the same combination of S&C. That is, the switches and crossings are the same type, eg Cv – 13.

A full list of S&C combinations for both 113A and RT60 are found in section A of the TDH.

- 19 – Copyright – P.J. King A Guide to Permanent Way Design e. Speed Characteristics

These are defined in section B of the TDH on pages B2.1 – B2.3. The figures to be noted are:

Maximum Values Negative Cant = 80mm Cant Deficiency on Main Line = 110mm Cant Deficiency on Turnout Line = 90mm - 113A = 110mm - CEN60 Rate of Change of Cant and Deficiency = 80mm/sec – 113A and CEN60

f. Design Guidelines

Before locating the S&C the alignment of the Main Line should be designed. The turnout, or crossover, can then be located following the criteria below, which are listed in order of preference:

1. Locate on straight track if possible 2. Avoid vertical curves particularly through switches 3. Do not locate on canted transitions

If located on curved track the geometry of the S&C will change. To calculate the revised radius the following formula should be used:

Re = Rm x R

Rm+/-R

Rm = radius of the Main (or through) Line R = original radius + value is used if the two curves concerned are the same flexure - value is for different hand curves

- 20 – Copyright – P.J. King A Guide to Permanent Way Design g. Summary

1. The basic units of S&C are switches and crossings. 2. Turnouts and crossovers are a combination of these units. 3. There are currently two designs - 113A vertical and CEN60 inclined. 4. CEN60 layouts are for high speed connections from SG switches onwards. 5. S&C are always fitted onto the designed alignment of the Main Line. 6. S&C must not be placed on canted transition curves. 7. Vertical curves should be avoided through switches. 8. Other combinations of S&C are used, see attached sheet, but they are beyond the scope of this course.

h. References

1. TDH sections A and B. 2. Standard Drawings – RE/PW series.

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Track Layouts a. Typical Two Track Layout

Diagram 1

Down Line G

Up Line G

Gauge - G (Four Foot) = 1435mm Six Foot – S = 1970mm

All dimensions are measured from the running edge (RE) of the rail, see inset.

The six foot interval of 1970mm is a standard dimension but can be varied according to site conditions and clearance requirements.

The track designations show standard left hand running with the Up Line generally going to London.

The Cess is the safe walking area beside the track.

- 22 – Copyright – P.J. King A Guide to Permanent Way Design b. Typical Four Track Arrangement

Diagram 2

Cess

Down Line G

S Fast Lines

Up Line G

Down Line G

S Slow Lines

Up Line G

Cess

Standard interval between groups of lines, ten foot (T) = 3188mm. For details regarding track groupings refer to the TDH page A8.2.

This is a typical arrangement for tracks in the Midland Area. In other areas the Slow and Fast lines may be grouped together.

- 23 – Copyright – P.J. King A Guide to Permanent Way Design c. Cess Paths/ Position of Safety

These should be provided wherever possible and be included in track layout designs.

Width Distance from Nearest Track*/D

Cess Path 700mm 1300mm – Speeds up to 100mph 2100mm – Speeds up to 125mph 2750mm – Speeds up to 140mph

* - To be increased if radius is less than 1000m or vehicle kinematic envelope is greater than 3020mm.

Cess Path

The cess path should be +/- 500mm from the level of the top of the sleeper.

If a cess path cannot be accommodated it is possible to designate a ‘Continuous Position of Safety’. This is an area complying with the above dimension D but only 400mm wide.

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Clearances and Vehicle Envelopes a) Introduction

100 mm 450mm Window 100mm Opening

6000mm Vehicle Vehicle

Envelope Envelope Platform

100m 4780 mm – Min Height to accommodate OLE /Bridge Girder Rail Level - RL 50mm at 1100mm ARL or below

When carrying out a track design it is necessary to ensure that the clearances are compliant with standards. The requirements are laid down in Network Rail’s Group Standard ‘Requirements for Defining and Maintaining Clearances – GC/RT5212’.

To check clearances it is necessary that all structures beside and over the track are surveyed. (If they are in excess of 2.0m laterally - from the RE - and 6m vertically a survey may not be necessary.) The above diagram shows minimum clearances. It is a mandatory requirement regarding new structures and a preferred one for existing elements.

- 25 – Copyright – P.J. King A Guide to Permanent Way Design b) Key Elements

Clearances Structure to Vehicle Envelope and between Vehicle Envelopes Minimum Figures

i.) Normal Minimum  50mm (below 1100mm above RL)  100mm (in excess of 1100mm above RL)  450mm (Window Opening vehicles/2000mm – 3000mm above RL)  250mm (Window Opening vehicles – Train Crew only)

ii.) Reduced Minimum  25mm – 50mm (below 1100mm above RL)  50mm – 100mm (in excess of 1100mm above RL) Latter figure is only applicable to sealed window vehicles to a maximum speed of 125mph.

Passing Clearances between Vehicle Envelope Desirable Figures i) Minimum Desirable – Altered or Reconstructed Railways  380mm

Most of the above figures are minimum dimensions. Normal clearances are considered as anything between 2m and the above minimums. Standard GC/RT5212 lists the full scope of clearances. For elements less than 1100mm above RL the limits are as defined in the following section.

Whilst the above dimensions are minimum requirements it is desirable to locate all new structures at the following minimum offsets:

Speed/mph Offset/mm

0 - 100 2000mm 101 - 125 2800mm 126 - 140 3450mm

These dimensions will accommodate a cess walkway. If these cannot be achieved then a figure of 1500mm, straight and level track, should not require a detailed check of clearances – no path can be accommodated here.

- 26 – Copyright – P.J. King A Guide to Permanent Way Design c) Clearances below 1100mm

See following extract from GC/RT5212

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Key Points i) Platform offsets for straight and level track should be X = 730mm, Y = 915m ii) Horizontal offset, X, to be increased to 760mm for UK1 gauge trains – Eurostar etc iii) Offsets are given in the plane of the rails, this should be noted when the track is canted. iv) When the track has a radius below 360m allowances need to be made for vehicle throws d) Allowances for curved and canted track

When determining clearances it is necessary to make allowances for any cant and curvature. Vehicle envelopes, usually determined using ‘Laser Rail’, must be calculated using these factors. For more details see following section on Vehicle Envelopes. A method of calculating the effects of cant and curvature on vehicle envelopes is shown in NR/L2/TRK/2049, sections A7.1 and A8.10 – see following extracts:

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Typical Dimensions are:

Class 150 Sprinters, L = 23m, A = 16m Class 373 Eurostar, L = 22.15m, A = 18.7m

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e) Substandard Clearances

i.) If clearances less than those prescribed in GC/RT5212 exist they must not be worsened and every effort should be made to achieve a compliant clearance, they must not be reduced. It is also not permitted to reduce clearances so that a compliant dimension becomes substandard.

ii.) Derogations – For all substandard clearances derogation against standards must be applied for. This is to Network Rail who will apply to the HMRI. All such instances should be outlined at the Approval in Principle (AIP) stage. f) Tilting Train Requirements

All the above requirements apply to the WCRM tilting train, Class 390 Fiat/Alstom, except for a situation known as ‘Tilt Failure’. This occurs when a tilted train cannot unlock the applied tilt. In this case a minimum figure of 10mm for clearance is permitted. This occurrence is considered, by the manufacturers, only likely to occur once in the 30 year lifetime of the fleet. As such only one train is analysed in this condition. (It is possible that two trains in tilt failure will hit each other in a worse case situation.)

The current envelope for the class 390 vehicle is known as KE8 – CMR.

The Bombardier Class 221 tilting train is scheduled to operate on the Virgin Cross Country routes. The class 390 operates on the WCML and other associated routes.

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Extract from Laser Rail Analysis

To assess passing and structural clearances it is necessary to generate a simulation of the envelope of the moving train. This has been achieved by using a system known as ‘Laser Rail’. From manufacturers information and track data an envelope, the kinematic envelope, has been developed for most British railway vehicles.

The Laser Rail program will generate kinematic envelopes for given track geometry (including cant and radius), track tolerances and linespeed. From this model clearances to other vehicles and structures can be calculated.

The above diagram shows a composite envelope, more than 1 vehicle, on the left and a static profile on the right. The minimum clearance has been calculated as 26.1mm.

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It should be noted that the above analysis currently includes positional tolerances (maintenance) on the track position – these are to be assessed separately to be in accordance with GC/RT5212. They are:

Track type Tolerance/mm

High fixity, eg slab track NIL Medium fixity, eg long timbered track form +/-15 Low fixity, eg normal track +/-25

These figures are applied horizontally in the plane of the rails. Other allowances for reduction in cross level and sidewear are shown in GC/RT5212. For track works installation tolerances should also be added. These are found in Network Rail Company Standard ‘Track Construction Standards’ – NR/SP/TRK/102. g) References

Railtrack Group Standards

Title Reference Number

Structure Gauging and Clearances GC/RT5204 Superceeded Requirements for Defining and Maintaining GC/RT5212 Clearances Infrastructure Requirements for Personal Safety GC/RT5203 Superceeded in Respect of Clearances and Access Requirements for Defining the Size of Railway GM/RT2149 Vehicles Guidance on Gauging GE/GN8573 Railtrack Company Standards

Track Design Handbook NR/L2/TRK/2049 Track Construction Standards NR/L2/TRK/2102 WCRM – Engineering Management Procedures/Guidance Notes

Technical Guidelines for Infrastructure Clearance RT/WCRM/QMS – MP/APP/909 Requirements Freight Gauge Requirements over WCRM RT/WCRM/QMS – MP/APP/911 Routes

Others

Interfleet Document – West Coast Tilting Train ITLR/T6620/001 – Issue D Gauging Document – Draft 3 20 August 2001 Memo on Introduction of KE8 P King – 5 October 2001

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Permanent Way Design Manual

Hallade Design a. Introduction

Hallade is a method of design which uses offsets or versines measured against chords to realign railway curves. Over lapping chords with versines measured at half chord points are the basis of this method. Typically a chord may be 20m long.

The above diagram shows the basic elements.

A mathematical sequence uses the differences between the existing and smoothed, design, versines to generate track slues. This is shown in the table on the following page. Also included in this are cant data, six foots and radii. The calculations can be executed using a programmed excel spreadsheet. The proof of the method is shown in the Hallade Handbook (LMS Railway). Details of the calculations will be explained in detail later in this paper. This guide will explain:

 Design method  Alignment elements  Reverse transitions  Theodolite straights  Tying in of design  Adjustment using a Couple

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Permanent Way Design Manual

HALLADE CURVE REALIGNMENT STEVENAGE Site: 018 UP Details: FAST UID Job No: 23441 PSR. Comments:

Chord Length: 20 m Track Slue Convention:

New Prop Existing Calculated Curve Halfchord Existing New Existing Prop Sixfo Diffs Sum Moments Slues Comment Cant Sixfoot Radius Hand No Versine Versine Cant Cant ot Def (B/E) metres (B/E) 9999999 0 0 1 1864 1864 0 0 0 0 0 1 -1 99 9999999 1 0 1 1867 1867 0 0 0 0 0 1 -1 99 2 3 3 0 0 0 0 0 0 0 1868 1868 16667 9999999 3 0 0 1870 1870 0 0 0 0 0 0 0 99 9999999 4 0 -4 1875 1875 0 0 0 0 0 -4 4 99 LH 5 -1 -1 0 0 0 0 -14 -14 14 1880 1880 -50000 LH 6 -4 -4 0 0 0 0 -25 -25 25 1887 1887 -12500 LH 7 -3 -3 0 0 0 0 -26 -26 26 1888 1888 -16667 LH 8 -6 -6 0 0 0 0 -35 -35 35 1892 1892 -8333 LH 9 -4 -4 0 0 0 0 -40 -40 40 1893 1893 -12500 LH 10 -8 -8 0 0 0 0 -47 -47 47 1893 1893 -6250 LH 11 -8 -8 0 0 0 0 -52 -52 52 1894 1894 -6250 LH 12 -8 -8 0 0 0 0 -61 -61 61 1896 1896 -6250 LH 13 -10 -10 0 0 0 0 -65 -65 65 1896 1896 -5000 STAR 14 -12 -66 1898 1898 T -12 0 0 0 0 -66 66 -4167 LH 15 -11 -11 0 0 0 0 -69 -65 65 1896 1896 -4545 LH 16 -10 -11 -1 0 0 0 -75 -65 65 1893 1893 -4545 LH 17 -11 -11 0 -1 -1 2 -74 -65 65 1885 1883 -4545 LH 18 -11 -11 0 -1 -2 4 -74 -65 65 1875 1871 -4545 LH 19 -11 -11 0 -1 -3 6 -74 -65 65 1870 1864 -4545 LH 20 -10 -10 0 -1 -4 8 -76 -65 65 1865 1857 -5000 LH 21 -12 -10 2 -1 -5 10 -75 -65 65 1863 1853 -5000 LH 22 -10 -11 -1 1 -4 8 -74 -65 65 1863 1855 -4545 LH 23 -11 -11 0 0 -4 8 -73 -65 65 1861 1853 -4545 LH 24 -11 -11 0 0 -4 8 -75 -65 65 1862 1854 -4545

The survey is executed using, at least, the following equipment: a 30m tape, a steel or fibre chord line and hallade handles and ruler. Again this is detailed in the Hallade Handbook. During this survey clearances to all line side features are also taken.

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b. Design Method

Curve Halfchord Existing New Diffs Sum Moments Slues Hand No Versine Versine 0 0 0 0 0 0 0 1 0 0 0 0 0 0 2 3 3 0 0 0 0 3 0 0 0 0 0 0 4 0 0 0 0 0 0 LH 5 -1 -1 0 0 0 0 LH 6 -4 -4 0 0 0 0 LH 7 -3 -3 0 0 0 0 LH 8 -6 -6 0 0 0 0 LH 9 -4 -4 0 0 0 0 LH 10 -8 -8 0 0 0 0 LH 11 -8 -8 0 0 0 0 LH 12 -8 -8 0 0 0 0 LH 13 -10 -10 0 0 0 0 START 14 -12 -12 0 0 0 0 LH 15 -11 -11 0 0 0 0 LH 16 -10 -11 -1 0 0 0 LH 17 -11 -11 0 -1 -1 x -2 2 LH 18 -11 -11 0 -1 -2 4 LH 19 -11 -11 0 -1 -3 6 LH 20 -10 -10 0 -1 -4 8

Design Difference = Sum = Moments = Slues =

versines Existing Sum of Sum of - 2 x versine – differences Sums moments New versine

The above table shows the way the hallade formulas work to generate track slues from the existing and design (new) versines. From the existing and design versines Differences, Sums, Moments and Slues are calculated. Slues are derived by the sequence shown. This is programmed into a spreadsheet with the 4 right hand columns being protected to ensure that they are not corrupted. Any error in these cells will have a significant impact on the design as the design slues are the result of a cumulative process. The aim of the design is to regulate the versines to achieve a compliant geometrical design using circular curves and transitions. The alignment characteristics, including cant, cant gradient, rates of change, deficiency values and minimum element lengths need comply with section B of the Track Design Handbook in the same way as alignments produced by programmes such as MX Rail do.

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Permanent Way Design Manual c. Alignment Elements

Circular curves are achieved by having a series of equal versines. The transitions linking curves, to other curves or straights, need to have a regular, equal, increase or decrease in versine over this length. A 1/6th rounding at each end, in the versine, is also required. This is shown in both tabular and graphical form below.

Alignment Halfchord No Existing Versine New Versine Details 0 0 0 1 -55 0 Straight 2 15 0 3 30 0 4 15 4 5 35 25 6 25 50 Transition 7 60 75 8 105 96 9 115 100 10 65 100 11 115 100 Circular Curve 12 100 100

Typical Hallade Transition

140

120

100

40 Existing Versines

20 Design Versines

Versines / mm Versines 0 1 2 3 4 5 6 7 8 9 10 11 12 13 -20

-40

-60

-80 Half Chords

Straights have zero versines, although a more effective method of determining straights is to carry out Theodolite Straight surveys as described below.

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Permanent Way Design Manual

For Reverse Curves the Transition should have equal steps from a right hand curve to left hand curve, or visa versa, across the zero versine line. It is not permissible to have two different shape curves, different steps, each side of the zero line. This is shown in both tabular and graphical form below.

Halfchord Existing New Alignment Details No Versine Versine 1 -50 -50 2 -50 -50 Circular Curve 3 -55 -50 4 -40 -50 5 -55 -45 6 -30 -30 7 -15 -15 8 0 0 Reverse Transition 9 10 15 10 30 30 11 55 45 12 60 60 13 70 72 14 80 75 15 75 75 16 70 75 Circular Curve 17 70 75

Typical Hallade Reverse Transition

100

20 Existing Versines Design Versines 0

Versines / mm 1234567891011121314151617

-20

-40

-60

-80 Half Chords

A Theodolite Straight is surveyed by projecting a straight, with a theodolite, along the track looking both along the straight and back into the curve, or transition. Offsets are measured from one rail as shown in the table below. These figures are recorded in the existing tie column. A design straight is calculated and determined a suitable location, to tie into the hallade design and slues are generated from this as shown. (In doing the

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Permanent Way Design Manual survey it should be noted where the theodolite is set up and which rail and face is surveyed).

EXISTING PROPOSED PROPOSED HC TIE TIE SLUE 8 734 9 720 10 710 11 702 12 700 13 698 14 701

15 700 16 700 700 0 17 694 698 +4 18 691 696 +5 19 685 694 +9 20 685 692 +7 21 686 690 +4 22 700 688 -12 23 704 686 -18 24 699 684 -15 25 691 682 -9 26 685 680 -5 27 657 The above table shows the theodolite straight tying in at HC 16. This is also shown in the graph below.

Theodolite Straight

800

750

700 m

650 ffset/m

O Surveyed Offsets

600 Design Offsets

550

500 1 3 5 7 9 1113151719212325272931 Half Chords

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Permanent Way Design Manual d. Completion of Design

To complete a Hallade design it needs to tie in to the existing track alignment with zero slue and also tangentially. This is achieved by zeroing out both the slues and moments. This is shown in the diagram below.

Hallade Versines and Slues

0 Existing Versines 1 5 9 13172125293337414549535761656973778185899397101 Proposed Versines Slues -5 Millimetres Moments

-10

-15

-20

-25 Half Chords e. Design Techniques

A method of adjusting a design is to use a Couple. This is shown below and involves using negative and positive, or visa versa, adjustments of the versines to push the design one way and then to pull it back the other. These are shown at HC 31 and 38.

Curve Halfchord Existing New Hand No Versine Versine Diffs Sum Moments Slues LH 30 -12 -11 1 1 -4 8 LH 31 -12 -10 (-1) 1 2 -2 4 LH 32 -10 -11 -1 3 1 -2 LH 33 -10 -11 -1 2 3 -6 LH 34 -11 -11 0 1 4 -8 LH 35 -10 -11 -1 1 5 -10 LH 36 -10 -10 0 0 5 -10 37 -10 -10 0 0 5 -10 OB 92 38 -10 -11 (+1) 0 0 5 -10 39 -10 -10 0 0 5 -10 LH 40 -9 -10 -1 0 5 -10 LH 41 -9 -10 -1 -1 4 -8 LH 42 -9 -10 -1 -2 2 -4 LH 43 -16 -10 6 -3 -1 2 Generally the best way to do a hallade design is to go through the design one curve, or section, at a time and achieve a sensible design over this length keeping the slues to - 41 – Copyright – P.J. King

Permanent Way Design Manual manageable figures. The use of the excel spreadsheet and associated chart, as shown, should make this easier. To achieve a tangential tie in at the end of the design is often tricky and may involve some re-work of the adjacent curves and some less that perfect design, versines not completely smooth, to do this. To achieve a satisfactory design may also require versines in a curve to be varied by up to 1mm and the adoption of compound curves. These should be linked by transitions of at least 2 half chords. Generally transitions should be at least 3 half chords long.

The use of positive and negative versines, as shown in Section C, is an effective method of clearly identifying where the curvature changes. Positive versines for a right hand curve, is a sensible convention. The handing of curves may also be used and signage changed at the reverse point.

When designing parallel tracks it is often sensible to carry out a design on one track and ‘six foot’ the other to this rather than design two independent alignments. Clearly a correct tie in at each end of the ‘six footed’ line is needed. This is achieved by using the slues in these areas. f. Other Issues

As the design is reliant on the measured versines these must be as accurate as possible. This is factor of the survey methods, but an element in this is the choice of the correct chord length. Generally the measured versine needs to be at least 25mm, to minimise the percentage reading error, and should ideally match the applied cant. Half chord lengths of 10m and 15m are frequently used.

It should also be noted that this method should be used for short term design periods were the survey and realignment occur with a few weeks. This is because any significant track movement, through maintenance or general train movements, will invalidate the data as it is reliant on a cumulative technique. It is ideally suited to maintenance realignments. For checking speed characteristics and clearances the same techniques applied to alignment design using CAD methods should be used. g. Formulas

The radius R = C2/8V Where C is the chord length and V is the versine. h. References

1. Hallade Handbook / Theory and Design – LMS Railway 1946 2. Network Rail standard NR/L2/TRK/2049 / Track Design Handbook – Section B for Requirements for Speed. 3. Network Rail standard GC/RT5212 – Requirements for Defining and Maintaining Clearances.

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Permanent Way Design Manual

Survey Requirements

S&C DESIGN FOR RENEWAL WORK REQUIRED SURVEY INFORMATION

Points that must be noted: -

1. Types and angles of Crossings, eg – - 1 in 9 ¼ Cast Monobloc - 1 in 13 Semi Welded - 1 in 8 Built Up The crossing angle can be found on the V of the casting or in the blocks of other types of crossing.

2. Types of Switches indicating whether vertical or inclined – Av, Bv, Cv etc. (The switch type is marked on the heel blocks for flat bottom switches.)

3. Joint types within the S&C and the location of any insulated joints – type of and no of bolts.

4. Types of bearers – timber or concrete - and fixings.

5. Types of adjacent S&C.

6. Position of twists – indicated by baseplates changing from vertical (V) to inclined (Pan6/11).

7. Any areas of two levelled baseplates, eg V 2L 23 = 2 levelled V baseplate with an additional 23mm thickness

8. Location of any CWR adjustment switches within 150m of the extremities of the site.

9. Types of track adjoining S&C, eg – CWR FlatBottom on Concrete Sleepers. See following Plain Line Track Inspection form.

10. Point numbers – usually at switch tips or on operating mechanism.

11. Switch drive mechanism – Point Motor, Clamp Lock, Electro Pneumatic, etc – and the location of any extended timbers.

12. Any relevant cant markers and associated value of cant and radius.

13. The location of relevant final through timbers.

14. Ascertain if the existing, and adjacent if appropriate, S&C constitutes ‘strengthened’ in all components regarding CWR, eg, are switches and crossings strengthened? (8 No. 1” diameter high tensile bolts are needed at the heel & crossing blocks for strengthened S&C – this is only 113A).

15. The completed inspection should be recorded on the S&C inspection Proforma. Only use the FRONT sheet unless refurbishment of the unit is

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proposed. In this case, all the sheets are to be completed. This includes key dimensions on the S&C dimensions Proforma.

PLAIN LINE DESIGN REQUIRED SURVEY INFORMATION

Points that must be noted: -

For an inspection of the track associated with the renewal of a bridge or S&C the following data is needed:

1. Rail designation 2. Fixing type 3. Baseplate type 4. Sleeper type 5. Assessment of rail wear 6. Areas of incomplete ballast 7. Indications of formation failure 8. Measured gauge and cant 9. Average sleeper spacing 10. Area to be inspected

These items are detailed below. They do not relate to S&C, this should be inspected as outlined in S&C Inspection checklist.

The completed inspection should be recorded on the Plain Line Inspection Proforma.

1. Rails – Designation required

Type Designations Comments Bull Head 85lb RBS Virtually no 85lb rail will be found

95lb RBS Standard type of Bull Head rail

Flat 98lb Old type of FB rail, only to be found on secondary Bottom lines, 3 5 /8 ” / 143mm deep.

109lb All of these sections are 159mm (new) deep and 110A are not easily distinguished from each other 113 unless identified by rolling marks in the web of the 113A rail. These marks will identify the section type (113A) manufacturer (British Steel) and year. 113A is the most modern section.

UIC60 This is a new rail type introduced on line categories 1A, 1 and 2. It is larger than the above sections being 172mm deep.

Rail designations generally contain a figure, this refers to the weight of the rail. All of the above sections indicate lbs/yard except the CEN60 which refers to kg/m. For dimensioned rail sections see extracts from CEC/C/0005 & GC/EH005 in Appendix A. - 44 – Copyright – P.J. King

Permanent Way Design Manual

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Permanent Way Design Manual

2. Rail Fixings – Type required

Rail Fixing Type Comments Designation 85lb RBS Wooden Key See attached page, 53, from 95lb RBS Mills Tapered steel key Track Maintenance Handbook Pandrol Panlock key (BR) for details of the steel keys.

98lb Elastic spikes Elastic spikes and mills clips are 109lb RD fastening only used with timber sleepers. 110A BJB fastening The RD, BJB CS 3 and KT 113A CS 3 clip fastenings are not common on the KT clip Midland Zone. The most common Mills clips types are Pandrol clips and Fast Spring hoop clips clips. Pandrol 401A clips Most of these fixings are shown in Pandrol e clips the Track Design Handbook Fast clip NR/SP/TRK/0049 (TDH) page F2.2. CEN60 Fast clip G44 rail fixing

3. Baseplates/Chairs – Type required These are applicable mainly to timber sleepers.

Rail Type Baseplate Type Comments 85lb RBS AS1 Chair Typical Bull Head chair 95lb RBS

98lb See TDH, pages F1.1 – The type of baseplate is cast into 109lb F1.2, for a listing of the body, eg PAN11. 110A baseplate types. 113A

CEN60 None Only currently used with concrete sleepers and direct fastenings.

4. Sleepers – Type required

Type Markings Comments Softwood Identified by a preservative Rail attached via chairs (bull head treatment – typically rail) or baseplates (flat bottom rail) creosote

Hardwood Generally untreated – found in S&C

Concrete Manufacturer and type are Usually without baseplates – rails usually cast in – eg attached via cast in shoulders Tarmac/F40 See pages, F2.1 – F2.5, from the TDH for a listing of concrete sleepers. - 46 – Copyright – P.J. King

Permanent Way Design Manual

Steel Identified only by Always without baseplates – rails manufacturer attached via welded on shoulders

5. Rail Wear

This is split into Depth and Side Wear. The depth is a measure of the amount that the rail has worn down. Side Wear, which only occurs on curves, is a measure of the material lost from the side of the rail head.

The Depth is measured with a pair of calipers and is the maximum height of the rail. The Side Wear is measured with a special gauge to the instructions included with the gauge. (Birmingham office now has a gauge that measures both head and side wear.)

Evidence of gauge corner cracking should be identified if it is visible. This is shown in Railtrack’s special booklet ‘Rolling Contact Fatigue in Rails/A guide to Current Understanding and Practice – RT/PWG/001/February 2001. This generally features diagonal cracks on the head of the rail.

6. Areas of Ballast

Deficiencies in the ballast bed should be gauged from section D of Group Standard GC/RT5021 – Track System Requirements. This is in Appendix B.

7. Failed Formation

Areas of failure can usually be identified from either, wet beds, or evidence of material that has pumped up from the track bed in dry weather.

8. With a four foot or cant gauge measure the gauge and cant at the following intervals: Straight track – 20m Curved track – 10m

9. Over the bridge and the adjacent 20m, using a tape or wheel, determine what the average sleeper spacing is. (There may be insufficient sleepers for the track category and addition ones may be needed following the bridgeworks.) This requirement needs to be reviewed on a case by case basis for S&C renewals. (Sleeper spacing relates to the requirements in standard NR/SP/TRK/0102 – Track Construction Standards, regarding track category.)

10. For bridge works see section 9 above for survey limits. For S&C renewals the minimum length should be at least 40mm beyond the limit of renewal. This may need to be extended as specified in the job remit or up to associated adjustment switches.