University of Birmingham
School of Electronic, Electrical and Computer
Engineering
Railway Automation - Automatic Switch
and Crossing Inspection
9 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 .................................................................................................................. 7
3.1 Consideration of switch systems ........................................................................... 7
3.2 Current standards for switch inspection both in GB and Europe .......................... 8
3.3 Difference between condition monitoring and automatic inspection ................. 12
3.4 Current inspection solutions and gaps for the inspection of switches ................ 13
4
Case studies ................................................................................................................. 25
4.1 Laser based trolley for weld repair team ............................................................. 25
4.2 Smart bolts, nuts and washers ............................................................................. 28
5
Future work ................................................................................................................ 30
5.1 Publication plan................................................................................................... 31
5.2 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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Railway Automation - Automatic Switch and Crossing Inspection
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
ii
Railway Automation - Automatic Switch and Crossing Inspection
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)
iii
Railway Automation - Automatic Switch and Crossing Inspection
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
4
Railway Automation - Automatic Switch and Crossing Inspection
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.
5
Railway Automation - Automatic Switch and Crossing Inspection
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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Railway Automation - Automatic Switch and Crossing Inspection
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 systems
A 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.
7
Railway Automation - Automatic Switch and Crossing Inspection
Figure 1 – Schematic of a switch and its main parts
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 Europe
The 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.
8
Railway Automation - Automatic Switch and Crossing Inspection
An inspection standard usually contains:

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”.
NR/L2/TRK/001 (group standard)
NR/L2/TRK/001/A
NR/L2/TRK/001/B
NR/L2/TRK/001/C
01
NR/L2/TRK/001/D
01
NR/L2/TRK/001/E
01
01
01
NR/SP/TRK/054
NR/L2/TRK/0053
NR/L3/SIG/10663, Signal Maintenance Specifications, Part C
NR/SMS/PA11
NR/SMS/PB11
NR/SMS/PC05
NR/SMS/PF02
NR/SMS/PF01
NR/SMS/PF03
Figure 2 – NR switch inspection standards tree
9
Railway Automation - Automatic Switch and Crossing Inspection
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
inspection requirements document, which can be found in Appendix B - Switch inspection
requirements.
10
Railway Automation - Automatic Switch and Crossing Inspection
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.
Visual inspection tasks (without instrumentation)
Point machine inspection tasks
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
(both visual and instrumented)
functional test of actuation,
locking and detection mechanisms
specific detailed inspections
set out by manufacturers of
point machines
Instrumented inspection tasks
Track gauge and check
Cant, twist, alignment and
gauge measurements
levelling measurements
Top wear, side wear and
Cracks in the rails and
rail profile measurements
crossings
Torque checks
Figure 3 – Overview of inspection requirements
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Railway Automation - Automatic Switch and Crossing Inspection
3.3 Difference between condition monitoring and automatic inspection
Recently 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
Identify and predict faults by using
Why used?
a small amount of sensors which
are inexpensive and easy to install.
Automatic inspection
Inspect assets automatically and
according to inspection standards
What parameters are
Parameters that can provide useful
Parameters that need to be
measured?
information about faults
inspected
How is the data
Data is analysed using algorithms
Data is compared with good known
processed?
that can identify faults
values to identify out of tolerance
12
Railway Automation - Automatic Switch and Crossing Inspection
conditions
3.4 Current inspection solutions and gaps for the inspection of switches
A 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;

shift;

height;
13
Railway Automation - Automatic Switch and Crossing Inspection

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].
14
Railway Automation - Automatic Switch and Crossing Inspection
Distance between stock rail
and switch blade at the
point
Distance between stock rail
and switch blade at the
flangeway
Distance between the frog
and the check rail
Maximum throwing force
(for switch and movable
frog)
Throwing rod out of
adjustment
Problem in locking device
Obstruction
Problem in the detection
circuit
Level of tamping
rail and air
temperature and
air humidity
distance between
stock and switch
rail(placed at fwg)
distance between
stock and switch
rail(placed at point)
displacement of
throwing rod
shock sensor on the
frog
vibration sensor on
point machine
force to move the
switch
Maintenance
inspections
current in detection
circuit
Technological
solutions
active power sensor
Table 2 – Vossloh’s sensor capability in switch monitoring
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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
formed out of a combination of lasers and video cameras. Table 3 shows claimed potential
measurements for the ASIV vehicle.
15
Railway Automation - Automatic Switch and Crossing Inspection
Table 3 – Potential measurements for ASIV vehicle
Rail Type
Stock rail opposite a switch
rail:
Switch rail:
Stock and switch rail:
Closure rails:
Frog:
Frog nose and wing rail:
Measurement
Vertical wear
Gauge side wear
Field side wear
Gauge face angle
Gauge corner radius
Gauge face angle
Breaking of chipping
Gauge corner radius
Vertical height difference
Lateral gap width
Wheel contact point through switch point
Vertical wear
Side wear
Frog flangeway gap width
Relative height of nose and wing rail
Wear/Batter on Wing Rail
Batter/damage to frog
Surface damage: Batter, chipping
Wheel contact through frog
Wing 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;

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;
16
Railway Automation - Automatic Switch and Crossing Inspection

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;

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
17
Railway Automation - Automatic Switch and Crossing Inspection
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;

the SIM must be scheduled and assigned time slots to go through the rail network and
inspect the switches, and;
18
Railway Automation - Automatic Switch and Crossing Inspection

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);

𝑡𝑝 + 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 (𝑡𝑖 ).
Planning and
Travelling to the site
office work
and back
Carrying out inspection
𝑡𝑝
𝑡𝑡
𝑡𝑖
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.
19
Railway Automation - Automatic Switch and Crossing Inspection
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.
20
Railway Automation - Automatic Switch and Crossing Inspection
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
21
Railway Automation - Automatic Switch and Crossing Inspection
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
22
Railway Automation - Automatic Switch and Crossing Inspection
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
23
Railway Automation - Automatic Switch and Crossing Inspection
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.
24
Railway Automation - Automatic Switch and Crossing Inspection
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 team
It 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:
25
Railway Automation - Automatic Switch and Crossing Inspection

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.
Direction of
movement
Figure 9 – Position and orientation of the two line scanners
26
Railway Automation - Automatic Switch and Crossing Inspection
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;
27
Railway Automation - Automatic Switch and Crossing Inspection
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 washers
In 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
28
Railway Automation - Automatic Switch and Crossing Inspection
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.
29
Railway Automation - Automatic Switch and Crossing Inspection
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.
The Coniston trip as well as Talent Pool are programs which will help the author to develop
human skills, especially in research and business.
30
Railway Automation - Automatic Switch and Crossing Inspection
5.1 Publication plan
The 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 submission
It 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
31
Railway Automation - Automatic Switch and Crossing Inspection
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-railwaysystem_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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Railway Automation - Automatic Switch and Crossing Inspection
7
Appendix A – Leads tables
Table 4 – NR/L2/TRK/001/D01 leads table
Leads to:
GE/RT8000, Rule Book.
NR/L2/TRK/001/A01, Inspection and maintenance of permanent way – Inspection.
NR/L2/TRK/001/B01, Inspection and maintenance of permanent way – Rail
management.
NR/L2/TRK/001/C01, Inspection and maintenance of permanent way – Geometry and
gauging.
NR/L2/TRK/001/E01, Inspection and maintenance of permanent way - Installation
requirements, maintenance limits and intervention limits.
NR/L2/TRK/0053, Inspection and repair procedures to reduce the risk of derailment at
switches.
Relevancy:
NA
R
NA
R
R
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
NA
defects.
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.
RT/CE/S/054, Inspection of cast crossings and cast vees in the track.
NR/L3/TRK/003, Index to track engineering forms.
NA
L
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
33
Railway Automation - Automatic Switch and Crossing Inspection
Table 6 – NR/L2/TRK/0053 leads table
Leads to:
NR/SP/TRK/001 Inspection and maintenance of permanent way
Relevancy:
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
34
Railway Automation - Automatic Switch and Crossing Inspection
8
Appendix B - Switch inspection requirements
35
Railway Automation - Automatic Switch and Crossing Inspection
36
Railway Automation - Automatic Switch and Crossing Inspection
37
Railway Automation - Automatic Switch and Crossing Inspection
38
Railway Automation - Automatic Switch and Crossing Inspection
39
Railway Automation - Automatic Switch and Crossing Inspection
9
Appendix C – Risk assessment form
40
Railway Automation - Automatic Switch and Crossing Inspection
10 Appendix D – Web page
The following web page can be found at: http://postgrad.eee.bham.ac.uk/mariusr/index.html
41
Railway Automation - Automatic Switch and Crossing Inspection
11 Appendix E – Training needs analysis
Please turn to next page.
42