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London Bridge Point Failures Investigation Report
Draft 7 – NOT FOR CIRCULATION
Page 2 of 11
EXECUTIVE SUMMARY:
Following the August Thameslink blockade, four point failures occurred in the London Bridge Station area from
31/08/16 to 07/09/16, each resulting in significant delays.
The four points that failed were part of eight critical point ends installed in Christmas 2015 in preparation for the
opening of platforms 7 – 9 in August 2016 and the introduction of the new Charing Cross timetable. Prior to August
Charing Cross services were not stopping at London Bridge and the points were only in occasional use. Through
readiness reviews it was recognised that the points would be under increased usage post August and testing and
health checks were undertaken in preparation for this.
An investigation has been carried out to understand the root cause of the failures and has identified the following:
Three of the four failures were due to the incorrect detailed set-up and adjustment of the points
One failure was caused by a defective electrical relay contact
A further potential failure was prevented through the replacement of a faulty hydraulic component
There appears to be no similarities to the issues experienced following the January 2015 commissioning of London
Bridge Low Level (E&F switches design issue) or repeat software/component failures.
In response to the four failures expert engineers have carried out detailed quality assurance checks and
recommended:
Measures to optimise the performance and reliability of points
Enhanced maintenance practices for the clamp lock point design
Additional inspection and monitoring regimes
There is a high level of confidence within the Route and TLP teams that these measures will deliver a solid state of
reliability going forward.
The lessons learned from this investigation will be incorporated into future Thameslink stages.
London Bridge Point Failures Investigation Report
Draft 7 – NOT FOR CIRCULATION
Page 3 of 11
1.0) OBJECTIVE
The intention of this report is to:
To review the point end failures, the subsequent inspections and remedial work following the
commissioning and introduction of platforms 7, 8 and 9 at London Bridge station.
Draw conclusions focusing upon the failures, the maintenance activities preceding and following HL09.
Provide recommendations to prevent reoccurrence of similar issues.
2.0) BACKGROUND
On the 29th August 2016, platforms 7, 8 and 9 opened to the public. At the same time the usage of some of the
assets on the Charing Cross lines changed significantly as trains were routed to different platforms. In particular the
usage of 8 point ends have changed significantly; before the Thameslink blockade these points were swung on
average 13 times per week, in the week following the 29th August 2016, these points were swung an average of 293
times per week (see Appendix 1). In preparation for this change, quarterly maintenance services were completed
and swung multiple times to make sure there were no issues. The Remote Condition Monitoring (RCM) was
reviewed to confirm this.
In the two weeks following the 29th August, 2016, there have been four failures on these point ends accruing 25,000
minutes delay. London Bridge Delivery Unit, with the support of Works Delivery, Route Asset Management team
and the Thameslink Project, embarked on a series of inspections to ascertain root causes and take remedial actions
where required. These inspections were followed by further inspections undertaken by the National experts
2.1) Infrastructure Scope and Technical Information
The infrastructure assets considered as part of this report are limited to operational points either side of platforms 7,
8 and 9 at London Bridge Station and have three differing types of Point Operating Equipment (POE). TLP specified
In Bearer Clamp Lock (IBCL) on concrete bearers as the POE of choice, however in situations where the conductor rail
has to proceed past the switch tips, a HW2000 point machine is instead utilised. Two Rail Clamp Point Lock (RCPL)
operated points on wooden timbers are a temporary installation until a later stage, whereupon they will be
removed. A brief history of the 8 point ends can be seen in Table 1 below, a schematic of the layout around
platforms 7, 8 and 9 can be seen in Figure 1.
Table 1: Point Operating Equipment and Significant Dates
Point Number
POE
Installation stage Commissioned Last Service (Quarterly)
TL7151 IBCL 03/10/2015 January 2016 14/07/2016 TL7152 RCPL 17/10/2015 January 2016 14/07/2016 TL7154 RCPL 17/10/2015 January 2016 14/07/2016 TL7177 HW2000 26/09/2015 January 2016 27/07/2016 TL7178 IBCL 12/09/2015 January 2016 27/07/2016 TL7183 IBCL 12/09/2015 January 2016 29/07/2016 TL7187 IBCL 12/09/2015 January 2016 29/07/2016 TL7188 IBCL 12/09/2015 January 2016 29/07/2016
Points TL7181 remain Clipped and Padlocked out of use and detected until full commissioning at a subsequent stage.
London Bridge Point Failures Investigation Report
Draft 7 – NOT FOR CIRCULATION
Page 7 of 11
Table 2: Route Supported Remedial Actions and Observations
4.2) Critical Points: Specialist Inspections
On the 9th September, 2016 the two National experts for both Clamp locks and Switches and Crossings (S&C) visited
three point ends, 7151, 7152 and 7154. These points were selected as they are 3 of the 4 most utilised point ends
within this area and being clustered closely together provided the best possible access arrangements in the limited
time available. The team’s objective was to identify any potential faults or underlying conditions which were
previously missed by the maintenance based teams. A summary of the findings can be found in Table 3 below:
Table 3: Summary of Inspections Undertaken by the National Specialists and Findings
Point End Oil Level SimalubeDetection
Adjustment
Lock slide
protrusionTight Lock RAM issue
Debris
Nearby
7151 - 4xchanged
7152 1xchanged
Air appears to
be leaking (no
oil leak)
7154
Pot detached
(not
corrected)
7177Reverse lock
adjusted
7178
Nearly in red -
topped up (no
leaks)
7183Pot detached
and refixed
7187
Nearly in red -
topped up (no
leaks)
7188
Below red, 1lt
added (no
leaks)
Lube can loose
and retighten
Adjusted
detection
following test
013
L/H side
24mm, RHS
23mm
Paper moved
Point EndLock slide
protrusion
Lock
slide/lock
arm gap
TerminalsSchwihag
Rollers Back drive
Stretcher
BarRCM Oil level Hydraulic hoses
7151Adjusted on
site
Lengthen by
3mm. Now
corrected.
RCM not
working. Now
corrected.
7152
Insufficient
protrusion on
LHS currently
24mm should
be >24mm.
Actuator needs
packing
Insufficient
gap on RH
lock body
< 3mm
1) Rear crank
incorrectly
setup.
2) Stabilisation
plate moving
and requires
packing
Low
required
topping up
(600ml
added)
1) Hoses
require
replacement.
2) Split pins
retaining ram
incorrectly
installed.
7154
Insufficient
gap on LH
lock body <
3mm
Two lock
nuts missing
from
terminals
Clamp lock body
London Bridge Point Failures Investigation Report
Draft 7 – NOT FOR CIRCULATION
Page 8 of 11
All rectification works were either undertaken on the night or on the 11th September during a Sunday blockade.
Inspections of the remaining 5 critical ends continue through week 24, with any remaining inspections rectification
works planned undertaken on the 18th September and during week 25.
5.0) DISCUSSIONS AND CONCLUSIONS
5.1) The Four Point End Failures
Of the four failures, it is expected to be confirmed that two of the faults were down to component failures, the
hydraulic ram 7152 points and the relay 7183 points (awaiting confirmation from supplier). It is unlikely that these
faults would have been identified during regular inspections for the following reasons
- The hydraulic ram is covered by a shield which is not removed during any cyclical maintenance activity
and thus not fully visible during the inspection. In addition, even though the seal was damaged, there
was not any significant leakage, therefore the fault was not possible to prevent using Remote Condition
Monitoring.
- Cyclical maintenance is not prescribed for the type of relay which failed on 7183 points. The relays are
replaced on a 10 year cycle. The failed relay was manufactured in Feb 2015 well within this timeframe. In
addition the relay failed instantaneously, thus there would not have been any indication from RCM of
the faulty component.
One point to note from the failure of 7183 points is that it took approximately 40 mins from the fault occurring to
the CCT being contacted whom ultimately discovered the fault. The CCT at London Bridge can provide a vital role in
supporting the diagnosis of failures and resultant repair given their proximity to London Bridge Equipment Room
(LBER). They are able to test circuits entering and leaving LBER and have access to diagnostic equipment that the
Flight Engineers do not. In the case of 7183 failure, the CCT was able to test and rectify the fault. Accordingly it is
important they are formally in the communications protocol for ALL failures within their sphere of influence.
Even though it was it was unlikely to have affected these four failures it should also be pointed out that, there is
incomplete phone coverage within LBER. This is likely to hamper rectification of faults in the future.
The two remaining faults on 7178 and 7153 points were caused by the adjustable cam lock nut not being locked
resulting in the tappet being out of specification. Review of this fixing arrangement has concluded that it is unlikely
for them to come undone of their own accord, but left like that during a previous inspection either undertaken as
part of the regular cyclical maintenance or post HL09 blockade inspections. Potentially there are two underlying
reasons for this:
1) The time available to undertake maintenance during mid-week nights has reduced significantly due to the
constraints of accommodating project works in the area. Prior to onset of the Thameslink Project, there was
approximately 3.5hrs working time, the current comparable working time is 1 – 1.5hrs
2) Staff competency levels. London Bridge Signalling Technicians are expected to hold a wide range of
competencies and are expected to be ‘masters of all’, especially in failure circumstances. By way of
example, in just the eight sets of points considered by this report there are three different types of POE -
Clamp Lock, In Bearer Clamp Lock and HW2000 machine. Even though trained and certificated as
London Bridge Point Failures Investigation Report
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competent, it is very likely that established ‘best practice’ approaches adopted by some are not widely
shared.
The causes of the post HL09 point failures are dissimilar to those experienced following the TLP project stage LL09 in
the Bricklayers Arms area. These failures occurred straight after commissioning and were predominantly related to
back drive set up issues on long switches, E and F type switches. Although there are two E switches in the 8 point
ends around London Bridge station, these have been commissioned since January 2016 and the failures which
followed HL09, were not related to poor back drive setup.
5.2) Pre HL09 Inspections.
A significant amount of tests and checks were undertaken prior to the launch of HL09 no issues were highlighted
before the launch of HL09. Quarterly inspections undertaken in the month prior HL09, focused upon maintaining
safe operation and checking for common failure modes. Swing rehearsals and RCM reviews were prescribed to
highlight deterioration in the switch performance. It would be very unlikely that precautionary checks would have
identified the causes of the failure. The quarterly inspection does not mandate that the tappets and lock nuts are
checked and all failures, with the exception of the hydraulic ram, which was picked up during a post HL09 health
check, were instantaneous and catastrophic and therefore not predicted by RCM.
It is recommended that the contents of the precautionary maintenance should be reviewed to include inspections
which would prevent the issues identified during the failures and follow up inspections. These should be adopted in
preparation for future project phases. Furthermore, it is recommended that prior to a large commissioning phase or
a significant change is usage, the maintenance frequency should be evaluated with review to increase it if required
even as a short to medium term measure.
An additional fault team/resource was provided by London Bridge Delivery Unit, it should be recognised that this
decision helped minimise impact to service particularly in the case of 7183 points failure. As part of this
arrangement, it is recommended that length of cover should be reviewed and potentially extended if there is a spate
of failures which could extend beyond the additional covers expiry point.
5.3) Post Failure Inspections
Following the first two failures, two inspections regimes were put in place to identify other faults on the 8 critical
point ends. The first series of checks, tests and examinations were undertaken by teams from London Bridge
Delivery Unit and South East Works Delivery. They identified various other faults which could have ultimately led to a
failure. The second review of points undertaken by two the National experts for Clamplocks and S&C identified
further faults which in some cases should have been identified as part of cyclical maintenance or the first series of
inspections. A number of conclusions can be drawn from this:
a) The teams do not have sufficient awareness of the importance of critical settings and measurements on the
clamp lock system, particular in respect to those checked as part fault finding.
b) The best practice checks undertaken by the National S&C expert are not regularly employed within the
London Bridge Delivery Unit, particularly during fault finding investigations.
c) Some of the checks prescribed as part of the route based checks were not fully undertaken. This was
identified by the expert led inspections where faults which should have been identified previously were not.
In response to the three concerns above, it is recommended that staff undertake in-depth classes where they can
learn best practices for setting up clamp locks and fault finding. The training should also focus upon the importance
London Bridge Point Failures Investigation Report
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of having the correct S&C and back drive geometry required for switches and POE to operate safely and reliably.
Particular attention should be given to the adoption of the procedures in Reliability Improvement Alert 069 (RIA
069). Training should contain a sufficient practical element to allow teams to fully explore and understand the
operation of the POE and S&C system; opportunities the teams do not receive in the time constrained environment
of London Bridge. Before embarking on delivering the further classes, it is recommended that a full gap analysis be
undertaken with the support of the RAM team and TLP team where required.
Due to the criticality of clamp locks around the London Bridge Station and its eastern approaches, consideration
should be given to establishing a dedicated highly competent team focused on keeping these point ends reliable.
To support the adoption and continued adherence of the aforementioned best practices, it is also recommended
that the London Bridge S&T Engineers, Section Managers and Supervisors spend more time out on site with their
teams providing coaching and mentoring where required. If increased supervision was in place, it is also likely that
any reduction in the levels of expertise would have been identified and rectified before it became an issue. It is
important to point out that at present, the S&T team have a significant number of key vacancies which will prohibit
the adoption of this recommendation. This team should be supported wherever possible in filling these posts rapidly
with the correct calibre of staff.
The final point to note on the post failure inspections is that a number of points were found with low hydraulic oil
levels. RCM has oil level monitoring function, this should be utilised and its use briefed to the Flight Engineers.
5.4) Recommendation Summary
The following recommendations have been compiled from the previous Discussion/Conclusion section:
a) Bespoke practical upskilling should be arranged for all staff that maintain, install or fault find on S&C fitted
with clamp locks. This should focus upon improving the knowledge of clamplock and S&C best practices, and
back drive installation/setup, but the full contents of this class should be defined as a more formal gap
analysis exercise.
b) To support recommendation a) S&T engineers, section managers and supervisors should provide more on-
site coaching and mentoring.
c) Consideration should be given to setting up a clamp lock specialist team focused on cascading both S&T and
S&C best practices to assets in the London Bridge area.
d) The current post stage response team support should be evaluated before it finishes with the view to
extending it if there still risk of further failures.
e) As part of the pre-commission phase preparations work, an assessment should be made on each asset to
establish if there maintenance frequency should be enhanced.
f) In the advent of an S&T fault, the CCT should be contacted immediately to assist with fault diagnosis.
g) Full phone coverage should be provided to the entirety of the London Bridge Equipment Room
h) The precautionary maintenance undertaken prior to a project commissioning phase should be reviewed to
make sure that appropriate processes are built in to capture the issues seen in the failures and follow up
inspections
i) The current possession arrangements within the London Bridge area need to be reviewed with a view to
maximising the time available for staff to undertake maintenance.
j) The RCM function for monitoring hydraulic oil level in Clamp Locks should be utilised and monitored.
k) Review implementation of RIA069 and its effectiveness
London Bridge Point Failures Investigation Report
Draft 7 – NOT FOR CIRCULATION
Page 11 of 11
6.0) APPENDICES
Appendix 1: Comparison of Point Swings for both Before and After HL09
Appendix 2: Fault List for the London Bridge Critical Point Ends (FMS: Jan 2015 – Present Day)
Point Number Failure date Failure mode Failure cause
TL7151 04/02/2016 No normal detection No fault found
TL7152 11/04/2016 No reverse detection
Tamper damaged cable during engineering works
TL7152 01/09/2016 Points secured normal due to defect found on inspection
Defective seal on hydraulic ram
TL7154
08/06/2016 No normal detection
Loose nut on rear back drive rod
05/09/2016 No normal detection
Locking nut loose on adjustable cam causing detection to be out of adjustment
TL7177 No recorded faults
TL7178 31/08/2016 No normal detection Locking nut loose on adjustable
cam causing detection to be out of adjustment
TL7181 No recorded faults
TL7183 07/09/2016 No normal detection Defective contact on relay
TL7187 17/03/2016
RCM alarm, pump pressure high normal to reverse
Back drive out of adjustment and slide chairs contaminated with ballast
TL7188 05/01/2016 Points no reverse Grit contamination in lock body
Items in bold relate to the post-August 2016 period. Previous fault history from January 2016 commissioning
included for reference.
7151 7152 7154 7177 7178 7183 7187 7188 Grand Average
Total (Jan - Jul inc) 462 358 677 447 420 322 219 190 N/A
Weekly Average (Jan - Jul inc) 15.4 11.9 22.6 14.9 14.0 10.7 7.3 6.3 12.9
Week 35 (Post HL09) 227 516 499 No data 268 504 28 10 293.1
Point Number