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Safety Quality and Environment

Investigation into service disruption following a Circle line train coming into contact with scaffolding at Aldgate Station - 19 January 2010

FIR / LUSEA ref: 20001179

Photo taken during investigations on Tuesday 19/01/10, engineering hours

Mike Shirbon SQE Investigator

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Date of Issue: 26/04/2010

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Investigation into service disruption following a Circle line train coming into contact with scaffolding at Aldgate Station - 19 January 2010 LUSEA Ref.: 20001179

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CONTENTS PAGE Executive Summary.......................................................... 3

1. Terms of Reference.......................................................... 4 2. Methodology...................................................................... 5 3. Background....................................................................... 5 4. Incident Summary............................................................. 6 5. The Incident....................................................................... 6

5.1 Sequence of Events............................................... 6 5.2 Roles on Site.......................................................... 9 5.3 Change Control of Design..................................... 10 5.4 Clearance and Gauging Documentation.............. 11 5.5 Labelling of Gauges............................................... 13 5.6 Training of T002/3s................................................ 14 5.7 Human Factors....................................................... 15 5.8 Incident Response................................................. 16 5.9 Conclusions............................................................ 18 5.10 Previous Incidents................................................. 18

6. Findings of Investigation................................................. 6.1 Immediate causes.................................................. 6.2 Underlying causes................................................. 6.3 Root causes............................................................6.4 Observations.......................................................... 6.5 Actions already Implemented

20 20 20 20 20 21

7. Recommendations............................................................7.1 Recommendations................................................. 7.2 Observations..........................................................

21 22 23

8. Photographs...................................................................... 26 Appendix 1 ........................................................................ 27 Appendix 2 ........................................................................ 29

Distribution:

• Nigel Holness • Richard Coleman • Jill Collis • Investigation Team • Actionees


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Executive Summary At 0521 on the 19 January 2010 the first outer rail circle line train of the morning made contact with scaffold ladder beams that had been installed above the track the previous night. The ladder beams had been installed prior to LU clearance approval. A deviation from the unauthorised design resulted in the scaffold infringing the gauge. The hand-back process was not correctly followed and the use of the wrong gauging tool for the location gave incorrect information of the clearance available. There was minor damage to the roof of the train and no injuries were reported. There was significant disruption to all sub-surface lines for the duration of the morning. The report addresses the original design of the hoarding and the subsequent design alterations and how this instigated changes to the works. The process for managing such change is discussed and how works were instructed ahead of this approvals process. Hand back arrangements are explored and how this contributed to the incident, involving division of roles on site, time pressures and misinformation from the wrong gauging tool on site. The immediate causes were: • The train moved under scaffold ladder beams infringing the gauge • The track was handed back with scaffold infringing the gauge

The underlying causes were: • Initial hoarding design posed a risk to hand-back • Informal change to the design and work instruction • Change control and clearance approval processes not complied with • The design and work instruction was communicated verbally only • Deviation from intended scaffold design • Hand-back process was not complied with • Training in gauge identification is ineffective • Misleading labels on gauges.

The root causes were identified as: • No previous experience of similar hoarding design in LU • Time pressure from numerous delays to the project • Site management structure not effective • Clearance approval does not reference the means of gauging • Change control process not complied with by Mansell • Change of gauge labelling • Disconnect between clearance standards, drawings and training materials

Conclusions and recommendations are provided addressing the root causes listed above. In addition to the root causes there are 2 observations regarding the communication of investigation findings and the use of more than one commissioning manager where incidents affect more than one directorate.


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1.0 Terms of Reference

LU FIR Terms of Reference

Significant service disruption to SSR lines following a train striking scaffolding 19th January 2010

A formal investigation is requested into the incident of a Hammersmith and City train striking low scaffolding as it departed Aldgate station, and the resulting service disruption. The purpose of this investigation is to determine the causes of the incident and to identify the measures necessary to prevent future incidents. The investigation should: • Confirm the sequence of events that lead to the incident and the resulting

consequences • Identify why the incident occurred in terms of immediate, underlying and root

causes, in addition to any contributory factors. • Review the effectiveness of the post incident activities • Identify actions already underway to address the causes • Develop reasonably practicable recommendations to address the underlying and

root causes • Consider previous / similar incidents. The investigation should pay particular attention to: • The design, approval and inspection processes for temporary trackside

structures, • Gauging activities and subsequent hand-back arrangements in liaison with COO, • The competence of the persons undertaking such work, The investigation will be led by John Murrell with support from: • Mike Shirbon SQE Lead Investigator • Project staff • Trains Reps An interim / progress report shall be submitted on: 27th January 2010 The FIR shall be completed by: 30 March 2010

__________________________ Nigel Holness

BCV / SSR Service Director


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2.0 Methodology

2.0.1 The causes of the incident were investigated by:

• Interviews with key persons managing the works

• Statements from those involved

• Investigation meetings

• Reviews of emails, designs, standards and, training materials

• Photographs

• Root cause analysis techniques 3.0 Background

3.0.1 The works at Aldgate are enabling works, relocating a number of support columns to provide further space that is required for track extension to enable the introduction of S8 stock. LU is the client for the works and has appointed Mansell as the principle contractor, J. Gallagher are contracted by Mansell to provide scaffolding (amongst other activities) and the T002/3 is provided by Morson under contract to Mansell as the competent person for handing-back the track as fit for service, which includes gauging. There is a Mansell site manager and a LU site representative on site.

LU Project Management Team

(client for works)

LU Site Representative

(site based)

Mansell (Principle Contractor)Project Manager,Site Manager,Site Person in Charge

Protection Master

J Gallagher LtdScaffolders

MorsonT002/3

Construction Design Services(scaffold / hoarding designer)

LU Protection Resource Booking

Figure 1: Project contractual relationships

3.0.2 A fixed hoarding (blue section in fig 2 below) has been erected to separate the worksite from the District line track. Where the Circle line track joins the District line track, removable hoarding sections (cross hatched red in fig 2) are erected for weekend possession working so the works do not disrupt the District line services. The scaffolding referred to in this report is the scaffolding associated with the removable hoarding.


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Fixed hoarding (blue)

Removable hoarding (red)

Figure 2: Track and hoarding layout at Aldgate

4.0 Incident Summary

Time 0521 hours

Date 19 January 2010

Location Aldgate Station, Outer Rail Circle Line

What Happened The first train (T204) through this section made contact with overhead scaffolding that had been installed during the preceeding engineering hours.

Consequences Superficial damage was made to the train roof and there were no reported injuries. Significant service disruption occurred on all SSR lines whilst the scaffold was made safe and removed.

5.0 The Incident

5.1 Sequence of Events

5.1.1 Works at Aldgate required a number of weekend possessions starting on the 8 January 2010 From the first weekend possession it was identified that the removable section of hoarding (crossed hatched red in figure 2) presented a risk to hand-back due to the erection time required compared with the engineering hours

Circle line (outer)

District Lines


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available. It was identified that a redesign was required. Engineering hours had been cancelled on occasion due to the running of sleet trains. The first weekend possession used ‘Heras’ style fencing to separate the worksite from the District line track and a redesign was sought for subsequent possessions. Progressive design alterations were made to reduce the build time of the removable section of hoarding by providing maximum strength using the minimum amount of materials through effective use of engineering principles. On the weekend possession of the 15-17 January it became apparent that the installation of the removable hoarding design was a potential risk to timely service hand-back.

5.1.2 On the Sunday evening (17th) there was an onsite discussion to redesign the removable hoarding section to reduce the installation time. This was led by the Mansell Project Manager and attended by the T002/3, the LU construction manager and the J. Gallagher scaffold contractor. The LU site representative, the SPC and Mansell site manager attended this meeting in part, Mansell’s design contractor was not on site. The product of the meeting was a draft scaffold design that used triangular bracing attached to a horizontal ladder beam affixed to the underside of the overhead structure to provide support to hoarding panels. A gauge tool on site was used to measure the clearance available. It was later identified that this was the wrong gauge for this location. The triangular bracing was an addition to a design that had only been approved for possessions, but the gauge indicated that there would be sufficient clearance. Those in attendance were agreeable to the proposed design in principle and Mansell’s design contractor was instructed to formalise the design for submission to the LU clearance approval team. Later that day the Gallagher team leader was instructed over the phone by the Mansell project manager to survey how much scaffolding would be required and to install ladder beams on the horizontal plane underneath the gantry on the Monday night. This instruction was given in advance of LU approval of the design and would be the first time there would be scaffolding across the track in traffic hours at this location.

5.1.3 It is disputed what the instruction to the Gallagher scaffolder was. This is partly due to the design not being documented and therefore not subject to change control assessment or clearance approval and only verbal instructions being issued. There are claims that the instructions were clarified by the T002/3 and LU site representative prior to work commencing on Monday (18th) night, although this is disputed by the J. Gallagher scaffolder. Once the worksite had been set up the Mansell site manager and the LU site representative completed project based paperwork in the office whilst the site person in charge (SPC) completed site inspections. The Morson’s T002/3 was involved elsewhere on site where sleepers were being cut near point work and he was required to consider the implication on track integrity. The Gallagher scaffolders meanwhile installed the ladder beams horizontally in a vertical plane, over the track, underneath the horizontal ‘I’ beams that support the bus station (see figures 3 and 4). This was a deviation from the verbal instruction by Mansell and the unapproved design discussed on the Sunday night.

5.1.4 The LU site representative stated that he reminded the Gallagher scaffolders prior to the works that the ladder beams could only be installed in the horizontal plane. The T002/3 states that early into the shift he requested clearance approval documentation from Gallagher who stated the paperwork was on site somewhere,


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and when this wasn’t available he requested the beams be removed. Gallagher dispute this version of events and state they had not seen the designs and were acting on a verbal instruction from the Mansell project manager. As the revised design was yet to be submitted to LU for approval, the required paperwork would not have been available on site. The TOO2/3 and the LU site representative stated the option of removing the ladder beams was discussed when it was found they were in the vertical plane.

Figure 3 Figure 4 Scaffold ladder beams fixed horizontally in the vertical plane

5.1.5 All parties became aware of the issue of the scaffold being installed contrary to instruction at approximately 0350hrs on the 19 January. Statements indicate that discussions became heated as to the reason for the deviation from the intended unapproved design and then quickly turned to options available prior to the hand-back watershed at 0420. The scaffold labourers had packed up and all parties were conscious removal was likely to cause a late hand back and were aware of the consequences. It was suggested that the gauging tool on site be used to help determine options available as the scaffold was not built as instructed or to design and there were concerns that clearance approval was not available for the scaffold. The wrong gauge was used and it was incorrectly concluded that there would be 710mm clearance.

5.1.6 The T002/3’s concern at the absence of clearance approval paperwork were acknowledged by the Mansell site manager who stated he would take accountability for a retrospective application for clearance approval. This was based on the gauging measurements giving false confidence that there was 710mm clearance and was agreed by all parties. Both the site manager and T002/3 recorded this on their respective paperwork and the SPC handed the track back to the protection master and then to the LU track access control team.

5.1.7 The first train through this area made contact with the overhead scaffold and the train was brought to a halt with the train operator believing that the noise was a result of the train dragging something beneath the train. Station staff and the service controller were informed and it was identified at approximately 0600 - 0615 that the train had made contact with the scaffold overhead. There was a delay of 5 minutes


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to the response due to the train operator’s initial may-day request not being transmitted to the service controller due to a configuration error with the Connect system. Eleven customers were detrained to platform through the cars that were still in the platform. There were no reported injuries. Services were suspended through the Aldgate area with significant disruption to all SSR services. An emergency possession was taken after the peak at 1030 to remove the scaffold and through service resumed around 1150.

5.2 Roles on site

5.2.1 LU is the client for the works and maintains a presence on site through a site representative who acts as ‘eyes and ears’ for the project team. The LU site representative role is to consider LU's interests on site and to raise concerns with the site management team, but not to manage the works directly. In the event of a change to the planned works being required during the works, the LU site representative can agree this through the ‘short notice change’ process.

5.2.2 The Mansell project manager instigated the change in scaffold design and instructed the Gallagher scaffold team to install the ladder beams across the track without the change being formally notified to LU or a design being assessed as part of clearance approval. The revised scaffold design was not required until the weekend possession starting at the close of traffic on Friday, therefore there was no immediate reason for the works to be instructed ahead of the approvals process. Members of the LU project team were on site when the re-design was discussed and supported the submission to LU. The instruction to install the ladder beams was given over the phone by Mansell to Gallagher and prior to the redesign being submitted to LU.

5.2.3 Whilst the scaffold was being erected the Mansell project manager was not on site and the Mansell site manager and LU site representative were in the office completing paperwork, with the Mansell SPC the only part of the site management team visible. The issue of the scaffold being installed contrary to the project manager’s instruction was not identified until approximately 0345 hours when the T002/3 and LU site representative checked on the works. It is not clear why the scaffold works were able to be completed before the issue was identified. The investigation team believe the level of supervision on site and the SPC's unfamiliarity with the works programme are contributory factors. There is a disputed allegation by the T002/3 and LU site representative that the Gallagher scaffolders claimed design paperwork was available on site and efforts were made to find this paperwork, delaying the identification of the issue. Gallagher dispute this allegation and state they had only been given verbal instructions.

5.2.4 The programme of works is managed by a Mansell project manager who is not site based. Mansell maintain a site manager role who is responsible for implementing the works programme and for the site and site safety overall. The site manager is assisted by a site person in charge (SPC) which is a role defined in QUENSH. The SPC at this location took the lead on safety issues and monitored compliance on site with scaffold tags and the wearing of PPE amongst other supervisory activities. The SPC is responsible for receiving assurance from the


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T002/3 regarding track condition prior hand-back and communicating this to the protection master who then liaises with the TAC.

5.2.5 Section 51.3 of the LU QUENSH standard requires SPCs to have direct responsibility for the work programme in addition to other responsibilities including compliance with health and safety requirements. In this instance the SPC role was primarily focused on compliance with health and safety requirements, such as PPE, with the project manager and site manager managing the programme of works. The investigation team believe the division of the planning of works and site supervision functions is a contributory factor in why the deviation from the unauthorised work instruction was not identified earlier.

5.2.6 During the hand back the site manager took accountability for the lack of clearance approval, effectively overriding the responsibility of the T002/3 and the SPC. The hand back process does not permit the substitution of roles in this fashion, even by a more senior member of the management team. From interviews it appears that all parties supported this action, with the decision being taken out of the T002/3’s hands rather than him being pressured into agreement. Both the SPC and T002/3 are likely to have deferred to the opinion of a more senior member of the team, particularly in light of the misinformation from the tunnel gauge. For this project it may have been more appropriate for the site manager to also perform the SPC function with additional supervisory support or to have regular works programme meetings involving the SPC. However, all parties were in agreement that there was sufficient clearance.

5.2.7 The T002/3 assesses if track is safe for hand back and that all people, plant and equipment are clear of the track. Prior to the instruction to install the ladder beams above the track there had been no requirement to have a gauge on site. The removable hoarding across the track was designed to be removed prior to hand back and clearance to the fixed hoarding checked by tape measure. The main function of the T002/3 was documented as being to check the safety of the track following the ‘down the hole’ pilling that had been taking place in close proximity to the track. The tunnel gauge arrived on site with a separate T002/3 on the Saturday (16th) night which was the regular T002/3’s night off. The gauge was used on the Sunday (17th) night by the regular T002/3 to check if there would be sufficient space to safely install a redesign to the scaffold. The T002/3 recorded his objections to the ladder beams not having clearance approval but ultimately signed off the paperwork and verbally agreed that there was sufficient clearance. It is not clear from the T002/3 paperwork whether track was handed back as safe or not. The act of the site manager taking accountability from the T002/3 is thought to have had an influence on the clarity of the hand-back paper work which does make it clear whether the track was handed back or not.

5.3 Change control of design

5.3.1 As the initial hoarding design proved not ‘buildable’ in the engineering hours available, there were several design alterations proposed and issues discussed. The LU project team provided direct support to the Mansell design engineer and the LU project team noted that this close working relationship resulted in an informal


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approach to change control. The LU team felt it necessary to remind Mansell on several occasions that, whilst direct email was satisfactory for ‘agreement in principle’, formal change submissions should be used as a follow up to comply with the change control process. Changes to designs had also been submitted out of sequence and as hand drawn diagrams.

5.3.2 All changes to the project are required to be communicated to the LU project team via a change request form (CRF) or ‘Contractor’s communication’ which is recorded by LU document control and agreed or rejected as appropriate. In the case of a change to the scaffold design the CRF would prompt a clearance approval submission. The change to the scaffold design incorporating the triangular support was correctly submitted to LU, although the scaffold contractor was instructed to install the ladder beams across the track before the design was submitted to LU. It was not recognised that the ladder beams being installed above the track during traffic hours was a significant change. The revised position of the ladder beams was taken from a hoarding design not intended for use during traffic hours. The absence of clearance approval meant there was no design available for the scaffolder and was a causal factor in the deviation from the unauthorised design.

5.3.3 The change control process allows the impacts of changes to be assessed, in this case identifying the change in gauging requirement. The LU project team were present at the site meeting on the Sunday when the design and instruction were discussed but did not recognise that the design used selected elements of designs approved for possessions and therefore would not automatically be suitable for use in traffic hours without a different clearance gauging requirement.

5.3.4 The change control process and clearance approval regimes also ensure that decisions and designs are controlled documents and therefore all parties share a common understanding. The unauthorised change to the design and resulting verbal instruction to the scaffold contractor outside of these regimes resulted in there being no design available on site and a difference of understanding between the Mansell project manager and Gallagher scaffold team. The absence of a documented design with clearance approval resulted in the scaffolders installing the ladder beams in their ‘usual’ position (horizontally but in the vertical plane) and there being no reference for the T002/3 to check correct installation.

5.4 Clearance and gauging documentation

5.4.1 There are several documents that detail gauge and clearance dimensions; each use different reference numbers and labels and the documents do not provide cross references to each other. The disparate nature of these documents is reflected in the training materials and gauge labelling.

5.4.2 Category 1 Standard The top-level requirements for gauging on LU are set in the category one standard 1-156 ‘Gauging and Clearances’. This standard specifies the outputs in terms of performance, but as a category 1 standard does not provide practical guidance on implementation. The diagrams in this standard give detailed information on the clearance dimensions to be achieved. The diagram A1 (figure 5 below) shows which


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‘structure profile’ or ‘structure gauge’ is to be used for each area and is recommended to be printed in A1 for clarity.

Figure 5 – LU Gauges and profiles by location

5.4.3 Category 2 Standard The Category 1 standard was developed from and is supported by the Category 2 standard E 8013 A2. This also specifies the requirements for gauging in output terms and refers to the same diagrams as the Category 1 standard. The technical drawings of gauge tools referred to in the Category 2 standard are not available on the ‘Blue Pages’ website nor is there any information how to obtain them.

5.4.4 Practical guidance on gauging The investigation has located two relevant documents:

• Metronet Guidance Note 30015 ‘Operation of Tunnel Gauge’ (February 2006) This document is used as part of the training for all T002/3’s and contains limited instructions on the use of the gauge but not on the site specific selection of gauges. It is not clear if this is intended to cover both tube and surface gauges.

• Track operation procedures (TOPS) This document is believed to be available to LU and Tube Lines staff but not sub-contractors. It refers to 3 types of gauges and track which is misleading. It is not clear if TOPS includes both tunnel and sub-surface gauging. The list of gauges in TOPS does not include sub-surface gauges. The descriptions also do not agree


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with those in tables 1,2 or 3 below.

5.4.5 Tunnel Gauge Drawings There are a number of LU/Infraco drawings of different tunnel gauges as follows:

Drawing No. Description Pm 39525 New Works Tube Tunnel Gauge (Concreted Sections Only) Pm 9396 Arrangement and details of Tunnel Clearance Gauge (‘Green

Line’) (3560 dia. Tunnel) Pm 39290 New Works Tube Tunnel Gauge Ballasted Sections Only P 45833 Tunnel Clearance Gauge (3562 dia. Tunnel) for use for use

on all lines except Central Line White city to Liverpool Street P 45834 Tunnel Clearance Gauge (3562 dia. Tunnel) for use on the

Central Line White city to Liverpool Street P 44446 All Sub Surface Lines Tunnel Clearance Gauge

Table 1: Tunnel gauge diagram references

5.4.6 The information used in table 1 still exists although the T002/3 training course has been modified using the slide summarised in table 2 below.

Drawing no. General location of use

P45833E All concreted track except where other gauges are needed (see below) P45834B Central Line (White City to Liverpool St PM39525 Victoria Line, Jubilee Line, Piccadilly Line (Heathrow extension) PM9396C Bakerloo Line Embankment to Waterloo (Green Line Gauge) PM39290 Tube Line – ballasted track PM44446 Surface and subsurface track

Table 2: Tunnel gauge diagram references used in the T002/3 course

5.5 Labelling of gauges 5.5.1 All gauges have a serial number and some have a label as shown in figure 6. There is no means of identifying the gauge and the area in which it can be used from the label alone. The labels do not reference the diagram in the category 1 standard (fig 5) or the clearance diagrams in tables 1 or 2. T002/3s are expected to be familiar with all types of gauges as a result of their training. The clearance approvals process shows which clearance dimensions must be obtained on site although does not identify which gauge is to be used for that location.

5.5.2 Gauges manufactured by Lillie Bridge Workshops The fixed gauges used are unwieldy and present manual handling risks, so lightweight folding gauges were designed and manufactured by Lillie Bridge workshop. The folding tube tunnel gauges have an interchangeable part for use on the tube sections of Central and Northern Line. Records show that Morsons own 4


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tube tunnel section gauges and no sub-surface gauges.:

Drawing Number Description LBW0019/A Tube section LBW0019/A Northern Line Ext LBW0019/A Central Line Ext LBW0019/B Sub-Surface (inc A Stock) LBW0019/B Sub-Surface (ex A Stock) LBW0019/C Green Line

Table 3: Gauges manufactured by Lillie Bridge Depot

Figure 6: Original label Figure 7: Altered label Labels used on Lillie Bridge built tube tunnel gauges

(note the gauge used in the incident had the altered label)

5.5.3 The change in the labelling used by Lillie Bridge (MRIS) occurred following the purchase of a new engraving machine in the last 2 years. It is not clear why the change in label occurred, although it could be an error in transferring the label text from one machine to the other or an attempt to show that gauges are not just used in tunnel sections. There is no evidence of an assessment of the change (SRCC / CAP). The altered label is misleading and the same could be said of the original label as the diagram in the category 1 standard references different gauge profiles for the different tunnel sections.

5.5.4 The labelling of the gauge is a contributory factor in the incident as the T002/3 interpreted the label as an indication that this was the correct gauge for this location. The gauge was brought to site by a separate T002/3 on the 16 January and was used on both the 17 and 18 January to confirm that there was sufficient clearance. The fact that the gauge was already on site may have also been taken as additional confirmation by the T002/3 that the gauge was the correct one.

5.6 Training of T002/3

5.6.1 T002/3s are trained by LU at Acton including LU and Tube Lines (TLL) staff and contractor staff that may work on LU and TL infrastructure (TLL also provide


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their own T002 training course). The 5 day course covers track gauging and hand back of which tunnel gauging is a small part. Two days are spent in the classroom on underpinning knowledge and standards, of this tunnel gauging occupies about 1 hour. An additional hour is spent on the practical use of tunnel gauges. Following the course the trainees are mentored in the use of the gauges by a representative of their employers and their record of learning ultimately signed off by LU prior to the issue of the licence.

5.6.2 The key part of the training with relation to the selection of the correct gauge is the table reproduced in table 2 above. This table remains largely unchanged since the training was designed about 15 years ago although the actual gauges are no longer manufactured to these drawing numbers and additional (misleading) information is provided on the label. The course briefly covers the requirements of the Category 2 Standard E8013 which describes the C1 to C5 tube diagrams (C6 for the Victoria Line has not been added) and the E1 to E3 surface stock diagrams but does not attempt to relate to those in table 2 above.

5.6.3 The investigation team believe that the training of T002/3s is a contributory factor in the ability of the T002/3s to recognise the correct gauge and identify the correct gauge for the location. Both the T002/3 on the Saturday night and the regular T002/3 failed to recognise the gauge was the wrong one for the location on the Saturday, Sunday and Monday.

5.7 Human factors

5.7.1 There is evidence of ‘group think’ on site where all parties agreed that there was sufficient clearance for the scaffold. This occurred on both the Sunday night during the design discussion and on the Tuesday morning prior to hand-back. ‘Group think’ is where a collective try to minimise conflict and reach consensus without critically testing, analysing, and evaluating ideas: in this case deciding to continue hand-back despite the absence of clearance approval and the deviation from the intended design. There is pressure on project teams to prevent late hand back, both from COO due to service disruption and from project teams through cost penalties. This pressure would have encouraged the team to find a solution other than to remove the scaffold. It is likely that this pressure led the team to consider other options more attractive than removal. It is also important to consider the role of the gauge in the decision making, as this provided ‘confirmation’ that there was sufficient clearance. It is likely that the fact the gauge was already on site, combined with the misleading label was sufficient to bring the T002/3 to conclude that it was the correct gauge for that location.

5.7.2 A ‘confirmation heuristic’ is visible where the group have inadvertently sought to confirm they are correct, rather than trying to prove themselves wrong. This is a common human behaviour, as is giving equal weighting to all evidence. The absence of clearance approval should have been given greater weighting than the information obtained through the use of the gauge and the group decision, but this becomes increasingly difficult with time pressure. The T002/3 is the only person on site competent to hand-back track, but the effect of ‘group think’ resulted in the collective assuming this competence.


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5.7.3 The hand-back process requires the T002/3 to provide confirmation (or not) to the SPC who liaises with the protection master who ultimately hands back to the LU TAC. In this situation the involvement of the SPC within the group discussion on the Tuesday morning at 0410 and decision by his line manager to take accountability for the decision, removed the independence of the decision from the SPC. It is unlikely in this situation that a member of staff more junior in terms of years and position would override their manager. The site management structure should have taken account of the competence and experience of the individuals concerned when assigning roles and responsibilities.

5.7.4 In interviews with persons involved in the incident, it is apparent that there was time pressure throughout the project and acutely during the decision making prior to track hand back. Time pressure influenced the design changes to the hoarding, the site set up and the over all programme of works. The contract was awarded on the 10 December 2009 and works started on the 8 January 2010. The deviation from the unauthorised design was not identified until 0350 and therefore time pressure was felt due to the hand back watershed at 0420. All projects are aware of the importance of meeting hand back deadlines and the penalties for failing to do so. The investigation team has not found any evidence of Mansell being pressured to install the revised scaffold design ahead of the Friday works. Time pressure can increase the time taken to make a decision and can encourage risks to be taken. The combination of perceived time pressure and an increase in time required to make a decision can increase the likelihood of human error.

5.8 Incident response

5.8.1 The Connect Radio System The incident had a large impact on a number of lines and services due to its location which interfaces with the Metropolitan, Circle, Hammersmith & City and District lines. There were numerous suspensions and delays to services in this area following the incident at 0521 to approximately 0745. The decision was made to remove the scaffold under an emergency possession after the morning peak 1030 - 1100 to minimise disruption to customers. Services remained suspended through Aldgate until the scaffold was removed. A full time line is provided in appendix 1.

5.8.2 There was initial confusion when the train operator attempted to report the incident using a ‘mayday’ call to the service controller via the Connect radio system. At the precise location of the incident, the configuration of the Connect system was such that the mayday call was held in the system. As Circle line trains leave Aldgate station they automatically switch from the Metropolitan line to the District line service controller talk group due to the change in the track on which they are operating over. They also pass from the Aldgate radio frequency ‘cell’ to the Tower Hill ‘cell’, each cell is affiliated to the relevant line’s service control functions. For messages to be correctly routed requires the intended recipient of the message to have permissions for that cell.

5.8.3 The switching from one talk group to the other is achieved automatically when trains pass ‘tags’ affixed to the track side which tell the train that it is now in a District line area. In this instance the train had passed the tags but was still in the Aldgate


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RF cell causing a conflicting scenario as the system attempted to send a mayday call from a train in a District line location through a cell that the District line service controller was not affiliated with. The ‘tags’ are fixed to the track, therefore it is thought that the hoarding altered the RF cell boundaries, creating this configuration. Usually the message would be held in the system and sent to the relevant controller when the train either moved into the Tower Hill RF cell or moved behind the tags into the Metropolitan line area. In this situation the message remained ‘held’ as the train didn’t move. The situation has since been rectified by configuring the system so that both the District and Metropolitan service controllers have permissions for the Aldgate RF cell, therefore mayday calls will be directed to a service controller, either Metropolitan or District dependant on the position of the train relative to the tags.

5.8.4 The data from the Connect system shows that the train operator instigated a mayday call at 0524 which did not reach the District line service controller until 0559. This is likely to have been when the train was moved into the Tower Hill RF cell, during several attempts to move the train prio to the scaffold being identified as the obstruction. The Metropolitan line service controller contacted the train operator at 0529 via a ‘group call’, possibly in response to the train operator using his hand held to switch on to the Metropolitan line talk group and generate an additional mayday call.

5.8.5 Incident Management As a result of the Connect system configuration there was an initial delay as a lead for the incident was established between the Metropolitan and District service controllers. The response was also delayed by the initial reports of a noise under the train and the train dragging something underneath. Inaccurate initial reports are not uncommon for an incident of this nature and whilst there was a resulting delay to the response this did not affect the nature or outcome of the incident.

5.8.6 Due to the configuration of the Connect radio system, the District and Metropolitan service controllers both contacted the train operator to determine what the issue was. Usually only one controller would be in communication with the operator and this controller would take the lead for the incident. As there were initially 2 controllers involved there were some uncoordinated responses and the precise location of the train was unclear. The Tower Hill station supervisor was requested to walk up the tunnel to the train even though the rear carriages of the train were still in Aldgate station platform. It is thought the precise position of the train was unclear to those using Trackernet. As the train was across 2 track sections, discharging of traction current required both District and Metropolitan service controllers. The operator confirmed that he couldn’t speak to both at once and the District line service controller took the lead in managing the incident and liaising with the Metropolitan line service controller at 0559.

5.9 Conclusions

5.9.1 Time pressure It is evident that time pressure was a factor throughout the project and events leading up to the incident. Procurement issues resulted in different contract options being considered and the main contract being let on 10 December 2009, less than 1


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month before the first weekend possession. More immediate time pressure is visible in the issues with erecting the removable hoarding in the engineering hours available. In addition to what appears to be an onerous hoarding design, the Mansell project team cite, sleet trains, frustrated access and setting up protection as reducing the usable engineering hours available. It is concluded that time pressure contributed to the errors associated with this incident both in the planning stages and in the hand-back arrangements on the 19 January.

5.9.2 Removable hoarding design The original removable hoarding design took too long to erect for the engineering hours available, posing a risk to hand-back times. The means of affixing the hoarding is new and innovative for LU, although it is likely that similar arrangements will be required in the future to accommodate project or upgrade requirements. The suitability of the hoarding for the location and the time available led to the redesigns and is therefore a root cause of the incident. LU should give consideration to methods of separating sections of track for project works that meet project, safety and operational requirements.

5.9.3 Compliance with change control and clearance approval The issues with the removable hoarding resulted in a number of design changes in quick succession that were submitted to the project team for approval. The LU project team actively assisted in design development and at times the process became less formal with proposals and agreements exchanged via email rather than via the document control route. The decision to extend the ladder beams across the track was not considered to be a change by Mansell and therefore was not subject to a change request or clearance approval and there was no design available for the scaffold contractor or the T002/3. The ladder beams had been fixed in this position previously but only during a possession, the change was that they would be in place during traffic hours. The installation of the ladder beams in the horizontal plane during traffic hours has subsequently received clearance approval from LU, although it is the verbal instruction from Mansell to install an unapproved design without clearance approval that led to the confusion with the scaffold contractor.

5.9.4 Hand-back process not complied with There was a deviation from the hand back process in that the Mansell site manager took accountability for the decision from the T002/3 and the SPC. This was based on the incorrect conclusion that there was 710mm clearance and that the issue was with the absence of supporting clearance approval paperwork not the physical clearance itself. The hand back process does not permit the substitution of roles and this resulted in the concerns of T002/3 being over ridden. The hand back document from the T002/3 is unclear as his concerns are noted but the document is signed off making it uncertain if hand back was provided or not.

5.9.5 Site management roles The division of roles amongst site management team contributed to the incident in as much as the deviation from the intended design was not identified until towards the end of the shift and the role of SPC as defined in QUENSH is effectively shared between the site manager and nominated SPC. This informal arrangement and the relative experience of the SPC and site manager led to the deviation from the hand back process and the site manager making the decision for the SPC.


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5.9.6 Ownership of gauging documentation There are numerous documents from LU and the former Metronet organisation regarding clearances and gauging. These documents contain different information and there is little cross referencing between them. The variance in the documents is reflected in the course materials for T002/3 training. During the investigation it has not been possible to identify a single point of contact for gauging and a process that links clearance with gauging. The labelling of gauges does not aid their identification or link them to specific locations. The clearance approval process does not provide details of gauging requirements to T002/3, increasing reliance on T002/3 decision making.

5.10 Previous incidents

5.10.1 There are a number of incidents where the need to improve gauging have been identified and lessons were available to prevent this incident. The summaries below contain brief details of the incident and any recommendations that are relevant to the Aldgate Collision.

5.10.2 Dozer on engineer’s train struck bridge near Sudbury Town 8 June 2002 The incident occurred following a last minute change to the transportation of the vehicles (to be moved with cabs on). Route availability had been granted for similar dozers although it was not identified that the vehicle in question had been fitted with a roll bar. The report examines the short notice change process and the impact this has on compliance with safety systems. The recommendations address route availability process and management of short notice changes. Whilst this incident does not concern gauging, there are similarities with assumptions of suitability based on previous actions and last minute alterations to the planned works.

5.10.3 Train struck cable bracket at Farringdon 11 February 2004 Nine trains struck a cable bracket that had been installed as part of the Connect Radio enabling works the previous night resulting in broken windows and body side damage. The investigation concluded that both (Metronet SSL) project managers and the contractors were not aware of the requirement for clearance approval and the requirement to gauge items that were installed above the track. There was no T003 check as it was not recognised as ‘track’. The recommendations to increase the awareness of the clearance approval process and ensuring the competency of the SSL project staff have all been closed.

5.10.4 Train struck spreader beam at Wood Lane disused station - 27 Feb 2005 The first train struck a spreader beam that had been installed overnight on the platform of Wood Lane disused station as part of the preparatory works by Multiplex for the demolition of the station. This resulted in significant damage to the cab door, the cab, the passenger door and the car body. The beam specification was incorrect and installed to an incorrect design. The risk of fouling the gauge was identified but dismissed on the assumption the beam was level with the platform edge; no gauging was undertaken. The recommendations concentrate on improving the assurance process for the design. Recommendation 4 of the report required that evidence of mitigation is required for any activities that may introduce risk. Recommendation 1


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required more formal documentation for hand-back from the principal contractor (Multiplex).

5.10.5 Train hit signal post telephone Farringdon to Kings Cross Station Nov 2005 A Signal Post telephone installed the previous night by Metronet asset maintain staff was struck by the first train. The telephone had been installed the previous night but had neither clearance approval or had been gauged. The recommendations are complex but the most pertinent was that all teams within Metronet had not learnt lessons from the previous incident at Farringdon, with regard to clearance approvals and hand back requirements when installing or erecting structures in the railway environment. This was due to previous recommendations only applying to Metronet Projects Directorate.

5.10.6 Train struck track side equipment following track works Farringdon May 06 This incident differs from previous incidents in as much as it was the track that moved not the equipment. The track was replaced to an incorrect design and the track was gauged by a T003 who failed to identify that the brackets were foul of the kinematic envelope due to the track intervals at which the gauging was conducted. It was identified that manual handling issues (due the size and weight of the gauge) influenced how often it was used. The recommendations relevant to the Aldgate incident focused on Balfour Beatty Rail Projects providing assurance that their T002/3s were competent.

6.0 Findings of investigation

A root cause diagram is provided in appendix 2.

6.1 Immediate causes • The train moved under the scaffold ladder beams • The track was handed back with scaffold infringing the gauge

6.2 Underlying causes • Initial hoarding design posed a risk to hand-back • Informal change to the design and work instruction • Change control and clearance approval processes not complied with • The design and work instruction was communicated verbally only • Deviation from intended scaffold design • Hand-back process was not complied with • Training in gauge identification is ineffective • Misleading labels on gauges.

6.3 Root causes • No previous experience of similar hoarding design in LU • Time pressure from numerous delays to the project • Site management structure not effective


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• Clearance approval does not reference the means of gauging • Change control process not complied with by Mansell • Change of gauge label by MRIS • Disconnect between standards, drawings and training material

6.4 Observations

6.4.1 Evidence of consultation with key persons was seen, although anecdotal references have been made regarding consultation being rushed and meetings having to be rearranged. Whilst the consultation process is not thought to have had any influence on the nature of the incident or its outcome, it is indicative of the time constraints throughout the project.

6.4.2 Audits of the site by the LU project management team highlighted that a number of key documents were not available on site. These were not considered to be causally linked to the incident, although are indicative of the rushed set up of the site.

6.4.3 During the investigation there were a number of key commercial decisions that the project wanted to make using the findings of the investigation. Whilst every effort was made to produce the report in a timely manner, it is recognised that regular communication with the project senior team would have been beneficial for LU’s commercial interests. For incidents of this nature where there is involvement from both COO, CMO or Projects / Upgrades, consideration should be given to having joint commissioning managers or regular updates with key stakeholders. It is thought this can be achieved in such a way that the investigation team are distanced from commercial pressure or influence, by providing factual updates to persons sufficiently removed from the project.

6.5 Actions already implemented

6.5.1 Immediately after the incident, works requiring hand back approval were suspended on site whilst initial findings were established. Since the incident the LU project team have instigated the following actions:

• The T002/3, SPC and Mansell site manager were suspended from their roles pending the investigation. The Mansell project manager has been moved to a advisory role within the project.

• Issued a LU safety alert concerning confirmation that correct gauge tools are identified for the location.

• Conducted an audit of Mansell and Morson management systems regarding change control and gauging.

• Agreed a more formal short notice change process with Mansell using an agreed hierarchy of decision makers and approval process.

• Regular Monday and Thursday technical query meetings to discuss proposed changes arising from or prior to weekend work.


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• Reviewed current design documentation to ensure design and clearance approvals are in place.

• Provided additional and more frequent LU supervision of the works, particularly during weekend closures

• Changed the Mansell site manager role from 2 x 12hr to 3 x 8hr shifts and reviewed all staff CVs for suitability

• Implemented an engineering audit regime.

• Lillie Bridge Depot have recalled 55 gauges to check the labeling (as per fig 7). To date 27 have been returned with 25 requiring relabeling. Requests have been made in writing to the appropriate companies for the remaining 28 gauges, with fortnightly reminders.

• The service controller permissions regarding Connect radio at Aldgate have been altered to ensure ‘mayday’ calls will be routed to the correct controller.

7.0 Recommendations

7.1 Recommendations (LUSATS ref. 739) Item Recommendation Actionee End date

1 Requirements of Hoardings

Context Hoardings are used to separate worksites from operational environments. There are generic and site-specific requirements that hoardings must meet. Correctly identifying these needs and risk assessing the design prevents bringing unnecessary risks into the LU environment.

Recommendation a) Review LU’s operational and safety requirements for hoardings and develop a set of principles to be considered when risk assessing the suitability of hoarding designs.

b) Communicate the revised guidance to projects and upgrade teams

Malcolm Payne Infrastructure

Protection Manager LU

31st May

2010

Verification Activities Confirm that the revised guidance has been communicated to Projects and Upgrades teams and test a sample for understanding

Cathy Behan

SQE GM

30th June

2010


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2 Site Management Roles at Aldgate

Context The division of site roles at Aldgate affected the supervision of the work and the effectiveness of the hand back process by sharing responsibilities across multiple persons.

Recommendation Request the Mansell’s project management team review their site management roles and responsibilities for the Aldgate project taking account of QUENSH and track hand back requirements. The results of this review must be communicated to the LU project team and reflected in revised documentation.

Angel Ashcroft

LU Project Manager

30th April

2010

Verification Activities Assess the findings of Mansell’s site management review for compliance with QUENSH, change control and track hand back arrangements and monitor any action required at the appropriate project management meeting.

Warren Kencroft

LU Senior Project Manager

31 May 2010

3 Information from the clearance approvals process

Context Clearance approval is provided (or rejected) on the basis of an educated decision, informed by knowledge of the site clearances available and the stock that uses the area. Sharing the knowledge used to grant clearance approval with T002/3s promotes a common understanding reducing the likelihood of error.

Recommendation a) Review the information provided to T002/3s as an output from the clearance approvals process with specific regard to assisting T002/3s in making correct gauging decisions. Identify what information can be reasonably practicably communicated (e.g. relevant stock height and structure profile gauge) and implement this within the clearance approvals process.

b) Communicate the revised arrangements to be incorporated into the review detailed in recommendation 6.

Ian Calland

Head of Engineering

CMO

30 April

2010

Verification Activities To be incorporated within the action plan for recommendation 6.

Trevor Jipson

31 May 2010


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4 Mansell Project Health & Safety Management

Systems

Context The decision to redesign the scaffold and instruct the work outside of the change control process was key in this incident. Change control processes should be standard in project management systems and these should be aligned with LU’s systems.

Recommendation Seek assurance from Mansell that suitable change control process exist within Mansell’s project health and safety management system that are compliant with LU standards.

Angel Ashcroft

Project Manager

30 April

2010

Verification Activities Review the findings of the report and monitor actions to completion at the project management meeting

Warren Kencroft Senior Project

Manager

31 May 2010

5 Changes to Gauge Labelling

Context The label installed on gauges changed without an assessment of the change to a safety critical piece of equipment.

Recommendation Revise the ‘Production Control Procedure’ to require supervisor approval for compliance with the relevant drawing and/or standard for any changes to safety critical components including labelling. Communicate the change to relevant MRIS label manufacturing and calibration staff.

David Banks

Head of MRIS Track

Manufacture

30 May 2010

Verification Confirm receipt of the revised procedure and evidence of communication to appropriate staff.

Tony Jessop SQE Business

Manager

30 June 2010

6 Review of Clearance and Gauging Process and Documentation

Context During the investigation it was noted that there is disparity between the processes and documentation regarding clearances and gauging. Consistency is required to reduce the likelihood of error.

Recommendation a) Provide DART with an action plan detailing how the clearance and gauging issues identified within this report will be addressed. The action plan should include immediate and long term actions and address as a minimum:

Trevor Jipson Head of Track Engineering

5 May 2010


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• Consistency across relevant standards and document control,

• Consistency in drawings and reference numbers used,

• Clarity of gauge labelling and consistency with standards and drawings,

• The relationship between clearance and gauging standards and the clearance approvals process (see recommendation 3),

• The content and variance in paperwork used by T002/3s for recording hand back

• The quality of the training materials / training standards used in TOO2/3 training,

• The competence assurance process for T002/3 staff,

• How assurance is sought for compliance with relevant standards,

• Clearance and gauging issues identified for further review

b) Review the process of clearance and gauging within LU to identify any issues not identified within this report. The report will identify further actions and a programme of work to implement the required changes.

Trevor Jipson Head of Track Engineering

31 October 2010

Verification Activities a) The milestones and actions from the plan will be monitored using LUSATS by DART

b) Conduct an audit of the clearance and gauging process to evaluate the effectiveness of the revised arrangements addressing the bullet points above..

DART

John Downes General

Manager SQE Audit

31 May 2010

6 months from the

closure of recommend

ation 6 7.2 Observations 1 Aligning the FIR Process with the LU Structure

Context. Historically FIRs had a single commissioning manager for formal investigations. In light of the new structure, at times it may be appropriate for FIRs that affect COO and CMO or projects / upgrades to have more than 1 sponsor to ensure all business needs are met.

Recommendation Revise the LU SQE investigations process to reflect the new organisational structure and the possible need for more than 1 commissioning manager where incidents affect COO and CMO or Projects/Upgrades.

Mike Shirbon

SQE Lead Investigator

Complete


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Verification Activities Review the SQE FIR guidance document

Marian Kelly

SQE Manager Environment &

Specialist Advisers

31 May 2010

2 Communication of the Investigation Findings

Context There have been a number of previous incidents on LU infrastructure were lessons were available regarding clearance approval and gauging. These lessons were not always widely communicated outside of the immediate teams involved.

Recommendation Communicate the findings from this incident across all project teams within LU using briefing documentation provided by SQE addressing:

• site management roles • time pressure and decision making • risks associated with hoardings (particularly

interfering with connect radio boundaries)

David Waboso and Alan Price

31 May 2010

Verification Activities Review a sample of meeting minutes confirming the findings have been communicated and check a sample of appropriate projects to confirm understanding.

Cathy Behan

General Manager SQE

30 July 2010

3 Configuration of the Connect Radio System

Context The configuration of the Connect radio system at Aldgate was such that the train operator’s mayday call was unable to be routed to the service controller at the time of the incident.

Recommendation Identify and test any locations on the network where a similar Connect configuration could exist affecting the routing of mayday or other calls. Make the necessary changes to ensure a ‘mayday’ facility is available at all locations irrespective of the position of the train.

Alan Moore Upgrades Operations

Manager, LUL Connect

30 April

2010

Verification Activities Provide assurance to DART that all areas covered by the Connect radio system have a working ‘mayday’ function.

DART

30 April

2010


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8.0 Photographs

Figure 8 Figure 9

Damage to the roof of the train

Figure 10: Incorrect gauge at Aldgate


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Appendix 1 – Incident Time Line

Date / Time Event Implication CoT 8 Jan to SoT 11 Jan

First weekend of works at this location – ‘Heras’ style fencing used for removable section

CoT 15 Jan to SoT 16 Jan

Erection of removable section of hoarding across Circle Line track – scaffold structure ‘stepped’ across track, not straight

Noted that design took too long to erect – risk could affect first District Line Services

16 Jan Planned works on site

17 Jan On site discussion regarding scaffold design for removable hoarding section. Agreement that hoarding should be straight and Mansell would submit re-design to LU

Re-design would be faster to erect and reduce risk of delayed hand back for SoT

CoT 17 Jan to SoT 18 Jan

Removal of removable section of hoarding for resumption of Circle Line services at SoT

18 Jan SoT Normal services resume on Circle Line Mansell re-design removable hoarding section and send to LU (arrives 19 Jan)

CoT 18 Jan Works undertaken by Gallagher to straighten removable section of hoarding. At the same time ‘ladder’ scaffold beams are rotated perpendicular to gantry and fixed in place.

Change to design was not approved.

0330 approx 19 Jan

The T002 raises concern and requests removal of ladder beams as no clearance approval has been provided.

Approved designs should have clearance certificate

0410 -0425 T002/3 returns to site; scaffold ladder beams not removed and scaffold towers packed away. T002, Mansell’s and Gallagher’s site persons in charge discuss options; (incorrect) gauge is used and all agree there is sufficient clearance for hand back and therefore Mansell site manager agrees to take accountability for absence of clearance approval. Mansell Site manager takes ownership for decision to hand back track, SPC goes along with this

Hand back was planned for 0440 creating time pressure

0426 Hand-back to TAC by Protection Master

0440 Hand-back time

0521 Train 204 departs Aldgate (outer rail) and strikes scaffold. Incident is reported to service control as stalled train, possible something on the track.

0545 District Line suspended services between Whitechapel and Tower Hill both and the Outer Rail Circle line also suspended. ERU and DMTs dispatched to site.

0605 Circle Lines suspended.

0609 FIM introduced with DMT as Silver Control.

0611 H&C suspend Moorgate to Barking, and Metropolitan Line Baker Street to Aldgate.


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0635 Reports from site indicate train has scraped scaffolding in the platform area.

0701 Train 204 now able to be moved to Hammersmith depot via Edgware Road.

0710 District line resumes to severe delays. Circle, H&C and Metropolitan lines remain suspended through Aldgate area.

0745 Through H&C service restored.

0747 ERU confirm scaffold ladder was the cause of the issue

1033 Emergency possession taken to allow the removal of the scaffolding ‘ladder’. The District line was suspended between Tower Hill and Whitechapel. The Hammersmith & City line was suspended between Whitechapel and Barking. The Metropolitan line remained suspended between Baker Street and Aldgate, and the Circle line remained suspended.

1102 Work completed. Protection arrangements now being lifted.

1123 Hammersmith & City line resumes to Barking, line status severe delays.

1156 Metropolitan line resumes to Aldgate.

1207 District line resumes to all destinations.

1211 Circle line service now severe delays as service re-populates.

Appendix 2

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London Underground - WhatDoTheyKnow

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