railway automation - automatic switch and...

University of Birmingham

School of Electronic, Electrical and Computer

Engineering

Railway Automation - Automatic Switch

and Crossing Inspection9 Months PhD Progress Report

Author: Marius Rusu

Supervisor: Clive Roberts

DATE SUBMITTED: 2012-08-01

Railway Automation - Automatic Switch and Crossing Inspection

Table of Contents

1 Introduction...................................................................................................................4

2 Project hypothesis.........................................................................................................6

3 Methodology..................................................................................................................73.1 Consideration of switch systems............................................................................73.2 Current standards for switch inspection both in GB and Europe..........................83.3 Difference between condition monitoring and automatic inspection..................123.4 Current inspection solutions and gaps for the inspection of switches.................13

4 Case studies..................................................................................................................254.1 Laser based trolley for weld repair team.............................................................254.2 Smart bolts, nuts and washers..............................................................................28

5 Future work.................................................................................................................305.1 Publication plan...................................................................................................315.2 PhD themes and submission................................................................................31

6 References....................................................................................................................32

7 Appendix A – Leads tables.........................................................................................33

8 Appendix B - Switch inspection requirements.........................................................35

9 Appendix C – Risk assessment form.........................................................................40

10 Appendix D – Web page.............................................................................................41

11 Appendix E – Training needs analysis......................................................................42

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List of Figures

Figure 1 – Schematic of a switch and its main parts..............................................................8

Figure 2 – NR switch inspection standards tree.....................................................................9

Figure 3 – Overview of inspection requirements.................................................................11

Figure 4 – Timeframe for switch inspection........................................................................19

Figure 5 – Switch rail fittings...............................................................................................21

Figure 6 – Smart bolt............................................................................................................22

Figure 7 – Three point machines..........................................................................................23

Figure 8 – The scanCONTROL 2700-100...........................................................................26

Figure 9 – Position and orientation of the two line scanners...............................................26

Figure 10 – Switch for BCRRE...........................................................................................27

Figure 11 – Gantt chart for laser based trolley development...............................................28

Figure 12 – Gantt chart for the research of smart fastenings...............................................28

Figure 13 – Important dates for the next 9 months..............................................................30

List of Tables

Table 1 – Difference between condition monitoring and automatic inspection..................12

Table 2 – Vossloh’s sensor capability in switch monitoring...............................................15

Table 3 – Potential measurements for ASIV vehicle...........................................................16

Table 4 – NR/L2/TRK/001/D01 leads table........................................................................33

Table 5 – RT/CE/S/054 leads table......................................................................................33

Table 6 – NR/L2/TRK/0053 leads table..............................................................................34

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Glossary of Terms / List of Abbreviations

Glossary:

Term Meaning

ASIV Automatic Switch Inspection Vehicle

DB Deutsche Bahn

DfT Department for Transport

GB Great Britain

NR Network Rail

ORR Office of Rail Regulation

RCM Reliability-centred Maintenance

SIM Switch Inspection and Measurement (train)

S&C Switch and Crossing

UK United Kingdom (Great Britain and Northern Ireland)

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1 Introduction

In recent years, there has been an increase in railway usage. As described by the Department

for Transport (DfT) and the Office of Rail Regulation (ORR), the railway was able to

accommodate an increase of 57% in passenger journeys and 26% in freight moved between

1996/97 and 2009/10 [1]. If the period up to recession is taken (1996/67 to 2006/2007) then

the increase in freight moved would be 45%.

The availability of the railway is shared between passenger transportation, freight

transportation and, not least, inspection, maintenance and renewal. With the increase in both

passenger and freight traffic, the allocation of time for maintenance and inspection has

become increasingly challenging. The maintenance and inspection of rail infrastructure is

usually done overnight and at weekends in order to have minimal or no disruption to the train

timetable [1].

An important asset of a modern railway is to have a maintenance free infrastructure. Whilst

this is very hard to achieve, Network Rail (NR), as an infrastructure owner, has expressed

interest in the use of automatic track inspection techniques in order to maintain the

infrastructure [1]. This will help to reduce the time allocated for inspection and therefore

increase the availability of the network. The use of automatic inspection allows infrastructure

owners to know the condition of their infrastructure more precisely. This is in part due to the

measurements that can be taken with better accuracy and more often by autonomous

inspection machines without the intervention of humans. The ability to know the state of the

infrastructure is an important requirement needed in order to move from periodic

maintenance to condition based maintenance, which is widely appreciated and recognised

throughout the speciality literature. Automatic inspection, together with condition based

maintenance would:

decrease inspection time and therefore increase availability;

eliminate the risks faced by railway workers;

decrease the need for human resources and consequently money spent on wages;

decrease maintenance time by adopting a condition based maintenance approach, and;

make available up to date information on the state of the infrastructure.

Apart from economic reasons for automation, there are also safety factors to be considered.

Railway switches need a considerable amount of attention if they are to be maintained in a

safe state. In 2002 seven people were killed and many others were injured when a train

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derailed while it was approaching Potters Bar train station [2]. The Rail Safety & Standards

Board concluded that the main cause of the accident was the movement of the points while

the train was passing over them (i.e. the switch not being able to correctly guide the train

along the right set of rails) [2]. Just five years later a similar accident occurred at Grayrigg,

where eighty percent of the passengers that were travelling were injured to some extent [3].

The cause of the accident was the poor condition of the switch at the moment of the accident

[3]. These two railway accidents prove that railway switches are safety-critical parts of the

railway and if they are not properly maintained there can be serious consequences.

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2 Project hypothesis

The hypothesis of this project is to investigate whether it is possible to eliminate the need for

human inspection of railway switches through the development of electronic inspection

systems. This project requires the development of inspection technologies that are able to

replicate existing inspection requirements practiced by infrastructure owners.

The academic challenges of the project are to:

identify and develop inspection equipment;

develop inspection algorithms, and;

verify that the technological solutions are at least as accurate as traditional

inspections.

Recent research has demonstrated the ability to know whether or not certain failure modes are

occurring in a railway switch by monitoring and analysing several physical parameters of the

point machine [4]. This project builds on previous work in the area of Reliability-centred

Maintenance (RCM); however, this research does not have the exact same grounds. Whereas

previous research focuses on condition monitoring, which can help infrastructure owners to

answer the following questions: “is there a fault?”, “what kind of fault is there?” and “when

is a fault is likely to occur?”; this research project aims to develop automatic inspection

techniques and prove that automatic inspection can be used to replace the manual inspections

that are imposed by railway standards. The output of this research must help to answer the

question: “does the infrastructure meet the standards?”. Therefore, the automatic inspection

techniques must replicate the manual inspections and also provide at least the same level of

accuracy.

The purpose of this research is to enhance the availability of the largest part of the railway.

Therefore, this research focuses on conventional main lines which carry passenger trains with

speeds of no more than 200 km/h and freight trains with speeds of no more than 120 km/h.

High speed lines are outside the scope of this research.

The work and findings of this research will also feed into Work Package 3 of the European

project AUTOMAIN (Augmented Usage of Track by Optimisation of Maintenance,

Allocation and Inspection of railway Networks, http://www.automain.eu/).

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http://www.automain.eu/


3 Methodology

During the first nine months of the research, the main effort has been focused on:

consideration of switch systems;

current standards for switch inspection both in the UK and Europe and inspection

practices focused on Network Rail;

available sensors and systems that are appropriate to be used for the inspection of

switches, and;

the identification of technology gaps and research to find possible solutions that

would fill these gaps.

3.1 Consideration of switch systemsA railway switch is a mechanical installation that enables trains to be guided from one track

to another. Switches are widely used in the railway infrastructure since they their function is

similar to that of road junctions. The most common switch is one that has a straight path

(switch operates normal) and a diverging path (switch operates reverse). Figure 1 shows a

typical switch and its main parts:

switch rails;

stock rails;

check rails;

wing rails;

crossings, and;

point machine.

Before and after a switch, the train runs on stock rails. When an approaching train faces the

switch, as marked in Figure 1, it is executing what is known as a facing-point movement and

the switch operates normal.

The train first encounters the switch rails, also known as the switch blades or point blades.

The switch rails are moved from side to side by the point machine and the position of them

sets the running path (in this case the switch operates in a straight path). The major cause of

the accidents at Potters Bar [2], Grayrigg [3] and Archway [5] was associated with the

condition of the switch rails and their associated parts and fastenings. Therefore, the author

believes that the condition of these parts is essential to maintaining safety.

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A crossing is a part of the railway switch and its purpose is to safely guide the wheels where

the paths of two rails intersect. Damage on crossings caused by running trains is generally in

the form of battering, deformation and cracks. Crossings are not easy to maintain in Great

Britain. A lack of precise information in terms of what needs to be repaired and how this

should be done makes it difficult to maintain crossings at their initial performance (e.g. “what

part of the infrastructure is not in its position and how much should it be corrected?” or “to

what precise shape and height must a crossing be corrected when weld repairs are carried

out?”) [6].

In order to safely guide the wheel sets through the crossing, additional check rails (also

known as guard rails) and wing rails are used, as marked in Figure 1 above.

It must be noted that Network Rail manages the switch as two separate parts:

the “switch”, which comprises of: switch rails, stock rails, check rails, wing rails and

crossing, and;

the “points” which comprises of: point machine and the associated fastenings that

ensure correct operation of the switch rails (moving, positioning, locking and

detection).

3.2 Current standards for switch inspection both in GB and EuropeThe railway infrastructure is maintained through the use of inspection standards. An

inspection standard is usually an internal and official document which is used to assess

whether or not part of an infrastructure is able to deliver what it was initially intended to

deliver.

An inspection standard usually contains:

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Figure 1 – Schematic of a switch and its main parts


a name (and description) of what must be inspected;

the tools needed to inspect it;

how the inspection is carried out, and;

how the measurements and results are interpreted in order to assess the performance

of the part.

3.2.1 Great Britain railway standards

The main railway infrastructure owner in Great Britain is Network Rail (NR). In order to

develop possible technologies that could replace human inspection, it is necessary to inspect

the switch inspection standards and express them in a clear and organised manner. The NR

switch inspection standards have been inspected by identifying a “key standard” and

exploring all the standards that are referred by the “key standard”. These standards refer other

standards, which were also inspected, and this process was repeated until all referred

standards were irrelevant, dead or repeated standards (the referred standard was already

inspected). This methodology of inspecting standards was adopted from a conference paper

published in 2010 [7]. The “key standard” for switch inspection is identified as

“NR/L2/TRK/001” and the one for the points “NR/L3/SIG/10663”.

Figure 2 – NR switch inspection standards tree

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NR/L2/TRK/001/

A01

NR/L2/TRK/001/

B01

NR/L2/TRK/001/

C01NR/L2/TRK/001/

D01

NR/L2/TRK/001/

E01

NR/L2/TRK/0053NR/SP/TRK/054

NR/L2/TRK/001 (group standard)

NR/L3/SIG/10663, Signal Maintenance Specifications, Part C

NR/SMS/PA11

NR/SMS/PC05

NR/SMS/PB11

NR/SMS/PF01

NR/SMS/PF02

NR/SMS/PF03


Each NR standard has a “reference documentation” section which contains all the references

to other NR standards. This helps the work since the references can all be found in one place.

Depending on the relevance of the inspected standards, a letter was assigned to each of them

as follows:

L – live standard (all references from that standard had been inspected);

NA – not applicable (the standard was irrelevant and its references were not

inspected);

D – dead standard (the standard is not in use any more), and;

R – repeated standard (a standard which was already inspected).

This information can be reviewed in Appendix A – Leads tables.

By inspecting the NR standards, all relevant GB switch inspection tasks were identified and

then reproduced and adequately categorised. This information is available in Appendix B -

Switch inspection ; it will be relevant as requirements for the technologies and methods that

will be used to perform automatic inspection.

3.2.2 European railway standards

In order to develop quality novel solutions to automatic inspection, European railway

standards must also be considered. A solution is more valuable if it solves a global problem

experienced by many railway infrastructure managers. Therefore, it is desirable for any

technological solution to be able to accommodate different types of railway infrastructure that

expose similar inspection requirements. An inspection template was designed in .xls format

and it was used to record different switch inspection requirements across three countries:

Great Britain, Germany and the Netherlands. It had been concluded that the way the

inspection is carried out varies from country to country but, as expected, the inspections do

try to answer similar questions (e.g. does the rail have excessive side wear).

3.2.3 Overview of railway inspection requirements

As already mentioned in the second chapter, this research focuses on conventional main lines

which carry mixed traffic. The inspection requirements were collected from different

European countries and it was found that the diversity is great. The design of the S&Cs is not

fully comparable between different countries and therefore it cannot be expected that the

inspection requirements follow the same methodology. Despite these differences, various

inspection requirements from across Europe were categorised and recorded in a generic XLS

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inspection requirements document, which can be found in Appendix B - Switch inspection

requirements.

The inspection requirements across the industry usually fall into one of the following

inspection categories:

visual inspection (done in general to ensure safety);

measured inspection (done in general to facilitate the maintenance process);

crack inspection (usually done using ultrasound techniques);

geometry inspection (cant, twist, levelling, alignment),

point machine inspection, and;

other inspections.

The above classification is useful in doing a rapid characterization of an inspection

requirement and identifying the nature of it. Figure 3 shows this classification in slightly

more detail by taking into account specifics about inspection requirements and how they are

carried out.

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Visual inspection tasks (without instrumentation)

Instrumented inspection tasks

Track gauge and check

gauge measurements

Cant, twist, alignment and

levelling measurements

rail side wear, switch rail damage, lipping, false flange damage, flangeways, crossing, fasteners, bolts, soleplates, baseplates, slidechairs, blocks, stretcher bars, lock stretcher bar, welds, ballast, RCF condition, cables, point heating, drainage, vegetation

Cracks in the rails and

crossings

Torque checks

Top wear, side wear and rail

profile measurements

Point machine inspection tasks

(both visual and instrumented)

functional test of actuation,

locking and detection mechanisms

specific detailed inspections

set out by manufacturers of

point machines


Figure 3 – Overview of inspection requirements

3.3 Difference between condition monitoring and automatic inspectionRecently there have been many technological advances in the area of railway inspection.

Many companies, as well as researchers, are now trying to develop innovative technologies

that are able to inspect and monitor the railway infrastructure rapidly, automatically, remotely

and with a reduced number of staff. Many of these advancements have been in the area of

condition monitoring techniques. Condition monitoring can greatly improve the performance

of systems and it is the solution for many researchers’ problems. This chapter aims to identify

the differences between condition monitoring and automatic inspection.

Condition monitoring aims at designing systems which identify faults. A common feature of

this kind of system is fault detection. This means that a system is able to identify a number of

faults while they are taking place in the monitored system. This does not mean that the

monitoring system must be able to differentiate between one fault and another. Fault

diagnosis is another feature of condition monitoring systems which provides the system with

the capability to distinguish one fault from another. Apart from the ability to detect and

classify faults, condition monitoring systems increasingly also have the ability to predict

future faults. This last feature of condition monitoring systems is known as fault prediction.

Automatic inspection aims to eliminate manual, traditional inspection by the use of new

techniques that are much faster and involve less human interaction. It focuses on inspecting

assets that are set out by the inspection standards. The inspection process has to meet the

requirements of the inspection standards (e.g. precision of measurement, conditions under

which inspection is carried out). The goal of the inspections is to identify all the assets that do

not meet the standards and also provide a form of quantitative information that can be used to

know how well the assets are within the standards or how far the assets are from being within

the standards.

Table 1 – Difference between condition monitoring and automatic inspection

Question\Technique Condition monitoring Automatic inspection

Why used?

Identify and predict faults by using

a small amount of sensors which

are inexpensive and easy to install.

Inspect assets automatically and

according to inspection standards

What parameters are Parameters that can provide useful Parameters that need to be

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measured? information about faults inspected

How is the data

processed?

Data is analysed using algorithms

that can identify faults

Data is compared with good known

values to identify out of tolerance

conditions

3.4 Current inspection solutions and gaps for the inspection of switchesA review of several companies (and their products) which offer solutions for the monitoring

and inspection of railway switches is set out below.

3.4.1 Current inspection solutions

1.) Eurailscout

Company headquarters: Amersfoort, The Netherlands

Technical solution: The “Switch Inspection & Measurement” (SIM) [8] is a vehicle based

switch inspection system that was initially designed in 2005 and was later further developed

to become what it is today SIM09 and SIM10. While the predecessor was a locomotive with

inspection systems, the later SIM09 and SIM10 are wagons which can be pushed or pulled by

other locomotives. These have a switch inspection system and a switch measurement system.

The switch inspection system has 8 cameras which are used to synchronously record the

switch from different angles. The data can be inspected offline in an office and it is claimed

that the following faults can be automatically identified through image processing:

missing fastening devices, depending on the type;

crumbling of concrete rail sleepers affecting safety;

cracks in the concrete rail sleepers affecting safety can be detected up to 0.5 mm, and;

ballast deficit and ballast surplus.

The switch measurement system is a laser measurement system which works by the

principle of laser triangulation. Each 20 mm a scan of the track profile is recorded while the

measuring system is moving at 40 km/h. The following can be calculated:

track gauge;

flangeway gap, and;

horizontal and vertical wear.

An inertial unit is mounted on the switch measurement system which allows for geometry

measurements to be taken. The following parameters can be delivered:

track width;

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shift;

height;

transverse gradient, and;

all derived signals.

Operational success: SIM is successfully used to inspect 212 switches in 6 hours every

two weeks in Amsterdam.

Future development: It has been confirmed that Eurailscout is working on a new version of

SIM which will have increased measuring abilities. In order to have a complete

understanding of the performance of the new SIM, a visit to this company had been

scheduled on 7th of September 2012.

2.) Strukton

Company headquarters: Utrecht, The Netherlands

Strukton has produced a number of technical solutions for the railway industry and they are

active in the field of switch inspection and condition monitoring.

Technical solution: As expressed in a report written by Strukton [9], their vision of a switch

inspection system is a measuring wagon and a video wagon used in conjunction with a

condition monitoring system for point machines and point heating. As documented in the

report, the measuring wagon measures “the condition of the blades, stock rail, gap, flange

way, crossing, check rail etc” while the video wagon is able to “check in the office for all

other items such as fasteners, rods, bolts, sleepers, track bed, pollution etc”.

3.) Vossloh

Company headquarters: Werdohl, Germany

For more than 10 years, Vossloh has monitored several turnouts. Their expertise in switch

monitoring lies in the sensors that they offer to different infrastructure managers. Table 2 was

reproduced from a document written by Vossloh [10].

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Table 2 – Vossloh’s sensor capability in switch monitoring

Technologicalsolutions

Maintenanceinspections ac

tive

pow

er se

nsor

curr

ent i

n de

tect

ion

circ

uit

forc

e to

mov

e th

e sw

itch

vibr

atio

n se

nsor

on

poin

t mac

hine

shoc

k se

nsor

on

the

frog

disp

lace

men

t of

thro

win

g ro

d

dist

ance

bet

wee

n st

ock

and

switc

h ra

il(pl

aced

at

dist

ance

bet

wee

n st

ock

and

switc

h ra

il(pl

aced

at f

wg)

rail

and

air

tem

pera

ture

and

ai

r hu

mid

ity

Distance between stock rail and switch blade at the

pointX

Distance between stock rail and switch blade at the

flangewayX

Distance between the frog and the check rail

X

Maximum throwing force (for switch and movable

frog)X

Throwing rod out of adjustment

X X

Problem in locking device X X X

Obstruction X X X X X X

Problem in the detection circuit

X X X X

Level of tamping X

Weather conditions X

This table, produced by Vossloh, shows the capabilities of their sensors in order to find the

best monitoring plan for switch failures throughout Europe.

4.) Zeta-Tech

Company headquarters: New Jersey, USA

Zeta-Tech is a company based in the USA which offers consultancy and solutions in the area

of rail transportation. They are proud to have clients from six different continents.

Technical solution: Zeta-Tech had developed a hi-rail vehicle [11] which is able to measure

the physical dimensions of a switch in a similar manner to the SIM wagon manufactured by

Eurailscout. Their vehicle uses ORIAN [12], a system marketed by KLD Labs, which is

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formed out of a combination of lasers and video cameras. Table 3 shows claimed potential

measurements for the ASIV vehicle.

Table 3 – Potential measurements for ASIV vehicle

Rail Type MeasurementStock rail opposite a switch

rail:

Vertical wearGauge side wearField side wearGauge face angleGauge corner radius

Switch rail: Gauge face angleBreaking of chippingGauge corner radius

Stock and switch rail: Vertical height differenceLateral gap widthWheel contact point through switch point

Closure rails: Vertical wearSide wear

Frog: Frog flangeway gap widthFrog nose and wing rail: Relative height of nose and wing rail

Wear/Batter on Wing RailBatter/damage to frogSurface damage: Batter, chippingWheel contact through frogWing rail profile (within field of view)

3.4.2 Collation of switch inspection tasks and available inspection technologies and their limitations

1.) Inspection tasks carried out by visual inspection

Visual inspection is one of the most frequent types of inspection.

Its main features that must be noted are:

it is carried out weekly to monthly;

by definition, this type of inspection covers only those inspection tasks which do not

imply the use of any measuring device;

is done in general to ensure safety, but, it is not limited to this;

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it is used to inspect the whole turnout; most of the parts that make up the turnout will

be visually examined to some extent to assess whether or not they are in a good

condition;

most problems can be identified at an early stage by carrying out this type of

inspection, and;

if a problem is identified but the gravity of it cannot be determined, then measured

inspection will be carried out and extra information will accompany the initial

findings.

In general, the visual inspection tasks are, but not limited to:

condition of switch/stock rails (wear, damage, lipping, RCF and false flange damage);

condition of crossing, wing rails, check rails and flangeways;

condition of stretcher bars, lock stretcher bars and their fastenings, and;

condition of track fastenings, soleplates, baseplates, blocks, welds, ballast and

vegetation.

Available solution:

The solution which is likely to succeed is video recording trains. They would record footage

of the turnout and the images would be inspected manually behind a desk and, as video

processing algorithms are improved, automatically by software which identifies flaws within

the recorded images. Currently this is in practice in the Netherlands and it is done by using

Eurailscout trains. It is believed that this practice helped to reduce the traditional on foot

inspection. Eurailscout states under the “1.1 Visual Switch Inspection” subchapter of the SIM

factsheet: “The fact that the monitoring frequency was halved in 2009 for the most important

switches is evidence of the success of the methods and the system.” [8].

Disadvantages and limitations:

personnel must be specially trained to be capable of judging pictures while

maintaining the same level of thoroughness;

images must be managed and stored in a big database as they can take considerable

disk space;

the inspections that can be carried out are limited to the ones which do not imply

touching any of the railway parts; rigidity and tightness checks cannot be covered

under this type of inspection;

automatic inspection of recorded images relies on image processing algorithms which

need to be heavily improved, and;

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visual recording trains must be scheduled within the network.

In practice, although most of the visual inspection that is carried out is done by just visually

inspecting the parts, on a few occasions force is applied to verify the rigidity and tightness of

different parts. Although these checks are part of the visual inspection requirements, because

they imply different inspection solutions, they are covered elsewhere in this report.

2.) Shape, size, gauge and position of rails and crossing

As previously expressed, visual inspection is one type of inspection which is able to identify

most of the problems within a turnout. Often, precise measurements must be taken in order to

better quantify the problem and identify the trends for wear.

In general, there are a considerable number of ways of determining the condition of the stock

rails and switch rails:

measurement of track gauge, check gauge, free wheel passage, flangeway gaps;

measurements of the side wear and top wear of rails and crossing, switch rail damage

and switch rail profile, and;

difference in rail heights, hogging of switch rails, switch toe position, toe opening in

switch.

Available solution:

The above inspection tasks have one thing in common. They all refer to the physical

dimensions of the rails. Because of this, a solution that would be able to measure the physical

dimensions of the rails would most likely be able to undertake all the necessary

measurements. Eurailscout and Zeta-Tech had both developed laser scanning systems which

are able to measure cross sections of the rails and therefore undertake necessary

measurements. These are the Switch Inspection and Measurement train (SIM) and the

Automatic Switch Inspection Vehicle (ASIV).

Disadvantages and limitations:

the distance between consecutive scanned sections of the rail at a given track speed

(e.g. 100 km) would be of the order of centimetres, not millimetres; this means that

some defects may not be recorded (e.g. switch rail damage);

grease and dirt on the switch rails can compromise the measurements;

hogging of the switch rail (which is a important measurement in GB) cannot be

measured since the space between the rail foot and the slide plates is hardly

accessible;

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Travelling to the site and backPlanning and office workCarrying out inspection


the SIM must be scheduled and assigned time slots to go through the rail network and

inspect the switches, and;

the ASIV must be driven by road to the access point which is nearest to the switch

and track possession is likely to be necessary.

Comparison between current GB practises and potentially improved practises

The current practise in GB is shown in Figure 4 where:

the inspection can be done either in the red zone (trains can pass on the inspected

switch) or in the green zone (a possession is granted and the line is blocked against

trains);

t p+ tt +ti≅ 2 hours, and;

the measurements are done manually using several marked gauges and, if not

disturbed by any trains, last no longer than 20 minutes (t i).

Figure 4 – Timeframe for switch inspection

Case 1: Handheld laser scanning device.

Advantage:

measurements would be done more accurately and human error is reduced

Disadvantages:

there is not a big decrease in the overall time needed to inspect the switch; this is

because the actual measuring does not take more than 20 minutes;

it is expensive to purchase the laser scanning device for every inspection team.

Case 2: Automatic Switch Inspection Vehicle (ASIV).

Advantage:

measurements would be done more accurately and human error is reduced.

Disadvantages:

if the vehicle is driven from the office to the site, it is likely that there will be no

decrease in the overall time needed to inspect a switch;

for safety reasons, track possession is likely to be required (work would be carried out

in the green zone only);

it is very expensive to purchase the ASIV for every inspection team.

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Case 3: Switch Inspection and Measurement train (SIM).

Advantages:

measurements would be done more accurately and human error is reduced;

if properly scheduled in the train timetable, it can automatically inspect the switches

and the maintenance team would have the task of just interpreting the results and

taking the required actions; the inspection would be done between services and there

would be a considerable decrease in the work carried but by the maintenance staff.

Disadvantages:

the inspection train must be scheduled properly;

the practice of keeping the inspection results on paper would have to be changed to

keeping them on a server; this must be done to allow the inspection train to dump the

results on a common storage space where the maintenance staff can immediately

access it and take corrective actions.

Taking into consideration the main advantages and disadvantages, the author believes that, at

least in GB, the third case is the only one which is worth considering.

3.) Switch rail fittings and tightness checks

The term switch rail fittings refers to all the parts that are connected to the switch rail for the

purpose of moving it, keeping it in a fixed position and detecting that the rails are in the

correct position. They are marked in blue in the following figure. This subchapter also

discusses the inspection requirement for verifying that different parts of the switch are tight.

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Figure 5 – Switch rail fittings

The following inspection tasks correspond to the GB standards, but other countries have

similar practises:

check for any broken, damaged, loose or distorted stretcher bars/brackets;

check for correct torque, integrity and any signs of weakening of bolts.

Video recording train

The stretcher bar and its brackets can be recorded by a video recording train as part of the

general visual inspection that must be carried out. Due to the fact that the orientation of the

camera relative to the track is the same at different inspection runs, the author believes that

images from different runs may be overlaid and matched just by applying an x and y offset.

This would help to detect any signs of deformation or movement which may have occurred

between different runs of the video recording train.

Smart bolts, nuts and washers

The requirement of knowing that all parts are tight can be fulfilled by the use of smart bolts,

nuts and washers. Some of these smart devices already exist while others are under research.

Stress Indicators Inc. manufactures smart bolts that have an indicator which is red if the bolt

is loose and black if the bolt is tight. An image processing algorithm would easily be able to

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identify “red spots” in recorded footage and therefore would automatically identify loose

parts in the switch.

Figure 6 – Smart bolt(image source: http://www.smartbolts.com/)

Limitation

One major limitation must be mentioned, which is the fact that some indicators may be

partially visible or even completely hidden, as is the case for the bolts that connect the

stretcher bar bracket to the switch rail. In this case the indicator is between the switch rail and

the stock rail and it is therefore not visible.

Importance of strength indicators

Knowing the full condition of the stretcher bars is very important as several trains have

derailed partially due to the poor condition of the stretcher bars. This aspect is also discussed

in Chapters 1 and 3.1. Although it is key to automatically detect loose bolts that connect

critical joints, it is desirable to monitor all bolts that are used in a switch, since the inspection

standards require many tightness checks to be carried out on various parts of the switch,

including track bolts.

Stretcher bar cracks

Stretcher bars and stretcher bar brackets also suffer from fatigue cracks. It is equally

important to be able to detect growing cracks within these parts of the switch. Because of its

physical shape and the forces that take place, some cracks grow beneath the stretcher bar and

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therefore it cannot be remotely inspected. In GB it is common practice to use a small mirror

to look beneath the stretcher bar and beneath the crossing in order to identify potential cracks.

4.) Cracks in the rails and crossing

Cracks in the rails are a common problem to all railways and much research has been done to

improve the methods of detecting them. There are many inspection techniques which can be

used to detect cracks but there is no one technique which is able to reliably detect all cracks

in rails and also run at a reasonable speed. To date the most widely used technique is

ultrasonic crack detection. The rail network in the Netherlands is checked for cracks with the

help of Eurailscout inspection trains. UTS-02 uses both ultrasound and eddy current

techniques in order to test the rails for cracks. In most countries, ultrasonic inspection trains

are used just on plain line, at most in the straight path of a switch. In general, manual railcar

or trolley based systems are used to scan for cracks on different parts of the switch. Crossings

manufactured form austenitic manganese steel (AMS) still pose problems since most

inspection techniques do not perform on this type of material.

The author believes that many improvements are still required in the area of crack inspection

and progress will not be easy.

5.) Point machine inspection

A point machine is a system which is usually placed either aside the track or in the four-foot

of a switch and its functions are: to move the switch rails, to lock the switch rails in place and

to detect whether or not the switch rails are in the correct position. There are many types of

point machine, some of which operate very differently. The main differences arise both from

the type of energy used to power the machine and the different mechanical solutions adopted.

Figure 7 – Three point machines

(a) HW 2000; (b) Bombardier EBI (stretcher bar embedded in steel sleeper); (c) HPSS

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Point machines have their own inspection requirements which are generally set out by the

manufacturer. The author believes that the implementing automatic inspection for point

machines would not be beneficial for the following two reasons:

diversity is great; one solution for automatic inspection may work on a point machine

but may not work for other point machines since the design and inspection

requirements are different;

some point machines, like the HW 2000, require many different inspection tasks to be

carried out, which means that much work would need to be carried out and the overall

benefits may not balance the investment.

newer point machines are being built for reliability:

- the High Performance Switch System (HPSS) [13] was build for reliability to

reduce both point machine maintenance and timetable disruptions; although its

brochure states “Designed for 25 year service life, with zero scheduled

maintenance” there are known failures of this type of point machine, and

therefore there is still a need for improvement;

- the Bombardier EBI point machine is used in the Netherlands and it is inspected

just once per year; this is proof that well designed point machines can reduce the

amount of maintenance time needed.

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4 Case studies

Chapter 3.4.2 presented the different inspection requirements for switches and the different

available solutions that could potentially be used to inspect them. This chapter looks at two

case studies for improving the technology readiness level for inspecting switches.

4.1 Laser based trolley for weld repair teamIt has been discussed that a considerable set of inspections are carried out to assess the shape,

size, gauge and position of the rails and crossing. It has been argued that the use of a Switch

Inspection and Measurement train would bring the most value to the railway.

The issue

Apart from the need to automate routine switch inspection, there is also a need to help and aid

welders. When weld repairs are carried out, the welders need to know both to what precise

shape the crossing must be repaired and the difference between the required shape and the

one they have welded. The answer to the first question can be provided by using the SIM

train. After welding, the worker is able to identify if the crossing profile meets the

requirements or if and where it still needs weld repairs.

The solution

A trolley based system would help to assess whether or not there is still a need for weld

repairs and, if needed, aid the worker with the necessary profile information that will assist in

carrying out the work.

Advantages:

helps welders to assess the quality of their work and decide whether or not there is

still need for weld repairs;

feed profile information to the welders;

reduce possession time, and;

because a switch is inspected more often than repaired by welding, maintenance

teams that carry our weld repairs are less numerous than the teams that carry out

inspection; this means that less laser based trolleys would have to be purchased.

The technology

With the help of new technology it is possible to build a lightweight laser scanning system

that would profile the rails and crossing. Micro-epsilon produces 2D/3D laser scanners,

named scanCONTROL. The 2700-100 is a laser line scanner which is particularly suited for

this application and its main features are:

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x-axis (width) = 148 mm;

number of points on x-axis = 640 points;

z-axis (height) = 600 mm;

z-axis resolution = 40 μm, and;

sampling frequency = 100 Hz (2 KHz for the scanCONTROL 2750-100 model).

Figure 8 – The scanCONTROL 2700-100(source: http://www.micro-epsilon.co.uk/laser-scanner-profile-sensor/Laser-scanner-selection/index.html)

The use of two lasers per each pair of rails (one stock rail and one switch rail) would allow

the profiling of the rails and crossing from the top down to the rail web, close to the foot.

Figure 9 – Position and orientation of the two line scanners

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Direction of movement

http://www.micro-epsilon.co.uk/laser-scanner-profile-sensor/Laser-scanner-selection/index.html


Future work

In order to facilitate the research carried out on switches, Birmingham Centre for Railway

Research and Education (BCRRE) arranged the delivery of a type B switch. Due to the

limited space in the research centre, the switch was delivered as switch rails and stock rails

without the crossing. The switch will be installed in the basement and it will be used in this

research project as well as other future research projects.

Figure 10 – Switch for BCRRE

On 30th July a meeting will be held with Phil Winship from Network Rail to establish the

inspection requirements and other details that may be relevant to this project.

After the meeting, the work will follow the following plan:

1. Decide on type of sensor (two 2700-100);

2. Decide on best programming environment, type of connection and mode of operation

(Lab View; synchronous between lasers, and triggered from a wheel tacho);

3. Decide on optimal sensor position and orientation (will be calculated based on

measuring requirements and worst case for S&C profile; work can be done in

autocad);

4. Design trolley; take measurements and compare it with MiniProf Rail measurements;

5. Develop algorithms for computing the required measurements, and;

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6. Compare the results with manual gauge measuring.

Figure 11 – Gantt chart for laser based trolley development

The first two steps have already been carried out; it is estimated that the rest of the steps will

take five months to complete, depending on the work load and the availability of necessary

parts (e.g. lasers, MiniProf Rail, switch dimensions/3D model).

4.2 Smart bolts, nuts and washersIn Chapter 3.4.2 the five main types of inspections which are carried out on a switch were

discussed and it was concluded that an important requirement is to visually inspect that all

parts of the railway are in place and undamaged.

The issue

In addition, it is essential that many parts are inspected for tightness to ensure that the switch

is in a healthy condition and its parts cannot suddenly move freely, thereby jeopardizing the

safe operation of the switch. A solution exists, SmartBolts, but it is not expected to solve all

the tightness requirements that the railway imposes. It is known that research is being carried

out to develop smart washers and a meeting with the researchers had been confirmed on

10th September 2012.

Future work

The work will be done by carrying out the following three tasks:

1. Research different types of fastenings across different switches in Europe;

2. Research current technology for automatic detection of loose fastenings, and;

3. Research ways of automatically inspecting the tightness the fastenings.

Figure 12 – Gantt chart for the research of smart fastenings

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Currently, confidential research is being carried out for the development of smart washers.

The relevant people will be contacted to see whether or not the automatic inspection of

switches can be improved by using these new devices. The current solutions and research will

be assessed against the different needs throughout Europe. The research will then try to cover

any resulting gaps within the objective of checking the tightness of switch fastenings.

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5 Future work

During the first nine months the research was aimed towards the understanding of current

inspection requirements which are practiced in the railway industry and also at understanding

the readiness level of different technologies which are available for automatic switch

inspection.

Although most of the of-the-shelf inspection technologies were considered in this report, it is

still necessary to carry out future research to precisely identify their abilities and limitations.

This is due to the fact that little information is published and some of it is over rated. An

example is the HPSS point machine, which was designed for 25 years free of maintenance,

but in reality faults do occur on these point machines and it does require maintenance.

During the next nine months, the research will focus on improving the current inspection

technology as well as developing new solutions. This will be done by following the time plan

set for the two case studies as well as investigating new potential improvements, which, at the

time of writing this report, are unknown.

Figure 13 – Important dates for the next 9 months

After the meeting with Phil Winship, it is expected that there will be good understanding of

the requirements for the laser based trolley and an order will be made for two laser scanners.

The meeting in Utrecht will help to identify the true performance of the SIM train as well as

any limitations that it may have. A meeting with Roger Bromley will soon be arranged in

order to discuss the research carried out on smart washers and how it can help to

automatically inspect the tightness of bolts in a railway switch.

30


The Coniston trip as well as Talent Pool are programs which will help the author to develop

human skills, especially in research and business.

5.1 Publication planThe workshop and congress at Lulea University in Sweden will help to identify new methods

of managing maintenance as well as networking with researchers with similar interests. A

paper will be written and presented at this congress.

It is expected that by March 2013 innovative contributions will have been made within the

case studies that are included in this report and at the end of the eighteenth month a journal

paper will be submitted. The author will try to publish the journal paper in “Journal of RAIL

AND RAPID TRANSIT”.

Although it is outside the next nine months, the author has an interest in participating in the

following events:

14th International Conference on Design and Operation in Railway Engineering,

COMPRAIL, September 2013;

PHM Society conference, September 2013.

5.2 PhD themes and submissionIt is expected that the thesis will be submitted in March 2015.

The main themes of the PhD thesis are likely to be:

Introduction

Methodology

Inspection requirements and maintenance practises

Ready to use inspection technology and inspection gaps

Case study 1: Laser base trolley for weld repair team

Case study 2: Smart fasteners

Case study 3

Future work

Conclusion

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6 References

[1] Department for Transport, “Realising the potential of GB rail,” 2011.

[2] Rail Safety & Standards Board, “Potters Bar derailment: report and recommendations”.

[3] Rail Accident Investigation Branch, Department for Transport, “Derailment at Grayrigg

23 February 2007,” 2008.

[4] J. A. Silmon and C. Roberts, “Improving railway switch system reliability with

innovative condition monitoring algorithms,” Proceedings of the Institution of

Mechanical Engineers Part F-Journal of Rail and Rapid Transit, vol. 224, no. F4, pp.

293-302, 2010.

[5] Rail Accident Investigation Branch, Department for Transport, “Derailment at Archway,

2 June 2006,” 2006.

[6] Notes of Meeting Held on 19th January 2012 in Birmingham with Mr Paul Richards

and Mr Phil Winship, both from Network Rail. [Interview].

[7] C. Roberts and C. Bouch, “A methodology for creating engineering models to help

assess the cost impact of new railway technologies,” in Proceedings of the International

Transport Economics Conference, Minnesota, USA, 2009.

[8] EURAILSCOUT, “SIM fact sheet,” [Online]. Available:

http://www.eurailscout.com/the-switch-the-most-sensitive-part-of-a-railway-

system_en.html. [Accessed 13 02 2012].

[9] F. R. Redeker, “Automain: the Self Inspecting Switch - The Strukton Approach,” 2012.

[10] V. Samuel Salas, “INNOTRACK - SP3 - WP3.3, Vossloh's sensor experience for

turnout monitoring system,” 2008.

[11] Zeta-Tech, “Development and Implementation of Automated Switch Inspection

Vehicle,” 2011.

[12] KLD Labs, “Rail Measurement Technology,” [Online]. Available:

http://www.kldlabs.com/rail.html. [Accessed 23 04 2012].

[13] IAD Rail Systems, “HIGH PERFORMANCE SWITCH,” [Online]. Available:

http://www.iadrailsystems.com/HPSS%20Overview%20-%20Standard.pdf. [Accessed

23 04 2012].

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7 Appendix A – Leads tables

Table 4 – NR/L2/TRK/001/D01 leads table

Leads to: Relevancy:GE/RT8000, Rule Book. NA

NR/L2/TRK/001/A01, Inspection and maintenance of permanent way – Inspection. R

NR/L2/TRK/001/B01, Inspection and maintenance of permanent way – Rail

management.NA

NR/L2/TRK/001/C01, Inspection and maintenance of permanent way – Geometry and

gauging.R

NR/L2/TRK/001/E01, Inspection and maintenance of permanent way - Installation

requirements, maintenance limits and intervention limits.R

NR/L2/TRK/0053, Inspection and repair procedures to reduce the risk of derailment at

switches.L

NR/L2/TRK/3011, Continuous welded rail (CWR) track. NA

NR/L2/TRK/2049, Track design handbook. NA

NR/L3/TRK/1202, S&C systems – Flat bottom full depth switches – Management of

fixed stretcher bar assemblies, lock stretcher bar assemblies, fastenings and associated

defects.

NA

NR/L3/TRK/1202/A, Action Tables. NA

NR/L3/TRK/1202/B, Patrollers Action Table. NA

NR/L3/TRK/3001, Ordering of switch and crossing components. NA

RT/CE/S/037, Requirements for maintenance of trackwork in depots by Depot

Facility Operators.NA

RT/CE/S/054, Inspection of cast crossings and cast vees in the track. L

NR/L3/TRK/003, Index to track engineering forms. NA

Table 5 – RT/CE/S/054 leads table

Leads to: Relevancy:RT/CE/S/056 Rail testing: non-ultrasonic procedures NA

RT/CE/S/057 Rail Failure Handbook NA

RT/CE/S/103 Track inspection requirements D

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Table 6 – NR/L2/TRK/0053 leads table

Leads to: Relevancy:NR/SP/TRK/001 Inspection and maintenance of permanent way D

NR/SP/TRK/0132 Maintenance arc welding of plain rails and switches and crossings NA

NR/WI/TRK/001 Track Inspection Handbook NA

NR/SP/CTM/011 Competence and training in track engineering NA

TEF/3008 Welders work return – switch repairs NA

TEF/3029 Detailed switch inspection report (053) NA

TEF/3042 Hand grinding record form (HG1) NA

TEF/3054 Switches and crossings welding assessment / replacement form NA

UIC Leaflet 716R Maximum permissible wear profiles for switches NA

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8 Appendix B - Switch inspection requirements

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9 Appendix C – Risk assessment form

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10 Appendix D – Web page

The following web page can be found at: http://postgrad.eee.bham.ac.uk/mariusr/index.html

11 Appendix E – Training needs analysis

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