Presentation on theme: "Managing Human Factors in Hong Kong through a Risk-based Approach"— Presentation transcript:
1 Managing Human Factors in Hong Kong through a Risk-based Approach 23rd International Railway Safety ConferenceManaging Human Factors in Hong Kong througha Risk-based ApproachPresented byPaul H.B. SENRailways BranchElectrical & Mechanical Services DepartmentGovernment of the Hong Kong SAR
2 Railway System in Hong Kong Railway Network of HKHR: 11 Lines, 84 StationsLR: 12 Routes, 68 StopsTotal Route Length: 218km5.1 Million pax / weekdayRailway System in Hong KongRelatively small railway network with a total track length of about 218 kmHong Kong is a densely populated city5.1 millions pax per weekday on the average (7.18 million population in HK as at mid 2013)Rail transport is an indispensable part for Hong Kong peopleHighly automated with minimum interventionHuman factors do play a vital part in rail operationHigh public expectation for level of service
3 Oversight on Safe Railway Operations Ensuring the adoption of appropriate safety practices by the railway corporations;Investigation ofrailway incidentsAssessing and following up the railway corporations' improvement measuresAssessing and approvingnew railways and major modificationsRailway lines operated by the MTR Corporation LimitedRB of EMSD is the regulatory body of all railway linesEmpowerment of the Mass Transit Railway Ordinance in Hong KongStatutory role to oversee the safe operation of the railwaysMain functions:Investigating into railway incidents;Ensuring the adoption of appropriate safety practices by the railway corporations;Assessing and approving new railways and major modifications; andAssessing and following up the railway corporations' improvement measures
4 What is Human Factors?“… the environmental, organisational, and job factors, and human and individual characteristics which influence behaviour at work in a way which can affect health and safety.” (Health & Safety Executive, UK)Human beings are fallible: Human errors & violationSomeone not doing the right thing at the right timePassenger behaviour: Publicity & education – a joint effort with operatorFocus on railway staff: contractors and MTR employees – Staff errors could be reduced (if not eliminated) by design and management
5 Continuous Monitoring Risk-based Model4 Phases1234Classificationof IncidentsRisk AssessmentHF Analysis accordingly to Risk RatingRecommendationCausationEquipment FailureHuman FactorsExternal FactorsRisk RatingLikelihoodConsequenceDeficiencySkillRuleKnowledgeRemediesContinuous MonitoringPlan-Do-Check-ActRisk-based model involves:Classifying incidentsAssessing the likelihood, consequence of any known hazards and determine the risk levelsAnalysing the HF: human deficiency (SRK) and performance shaping factorsRecommendation for incident specific remedies
6 Classification of Human Factor Incidents - Non-HF Related: Pure equipment failure & External Factors- Focus: HF related: Staff behaviour & Passenger BehaviourHuman factors incident classified by type of errorsClassified incidents recorded in Incident Data Management System
7 Trends of Human Factors Incidents Amongst the reportable incidents caused by staff behaviour, it is more common for the staff behaviour to have an impact on OSHExcept 2011: Measured by incident number, the impact on passenger / public safety overshot the OSH impactPast 2 years: Raise the attention on any HF elements involved in incidents
8 Risk Assessment by Risk Matrix Use a conventional risk matrix to determine the risk level10 levels of likelihood of occurrences – Similar occurrences in the past7 levels of consequence – Impact on public safety (measured by no. of fatalities) or service (duration of service disruption)Results in 4 levels of overall risk
9 Risk Assessment by Risk Matrix OR1Unacceptable and shall be eliminatedOR2Undesirable and shall be reduced by practicable control measuresOR3Tolerable but shall be further reduced if possibleOR4Negligible
10 Analysis of High Overall Risk Incidents Performance Shaping FactorsHuman DeficiencyTask design, interface design, competence management, procedures, person, environmentSkillRuleKnowledgeHFAnalysisHF analysis – to identify shortfall and find out ways to make goodUse performance shaping factors as a guide to comprehend the cause of incidents due to deficiency of staff in respect of skill, rule and knowledge (SRK)Best to be illustrated by HF incidents
12 Case 1: 21 January 2010, East Rail Line Failure of Data Transmission Network An evening peak at the East Rail Operations Control CentreFor the traffic controller Seeing is believing – The railway is safe and seen to be so byTracking the locations of trainsCommunicating with train captain with radioMaking public announcement
13 Failure of Data Transmission Network at East Rail Line All these operations at the East Rail Line Operations Control Centre are supported a data transmission networkFibre Distributed Data Interface (FDDI)
14 All of a sudden, all terminals became dumb, The traffic controllers at the East Rail Line Operations Control Centre could not track the locations of trainsRadio communication with all train captains was also lost.Train services on the whole line were suspended … all for safety30,000 passengers were stranded during the incidentIt takes an hour for recovery of train services
16 Case 1: 21 January 2010, East Rail Line Failure of Data Transmission Network Third-party supplier’s computer engineer was conducting a regular software audit to ensure the integrity of the data networkTo do so, he executed an off-line software optimisation program.He felt hungry and left for dinner!The program he had loaded was a slip of hand, it went online, overloaded the data network with junk data, and paralysed the FDDI networkcausing the failure.
17 Failure of Data Transmission Network at East Rail Line All these operations at the East Rail Line Operations Control Centre are supported a data transmission networkFibre Distributed Data Interface (FDDI)
18 Case 1: 21 January 2010, East Rail Line Failure of Data Transmission Network Third-party supplier’s computer engineer was conducting a regular software audit to ensure the integrity of the data networkTo do so, he executed an off-line software optimisation program.He felt hungry and left for dinner!The program he had loaded was a slip of hand, it went online, overloaded the data network with junk data, and paralysed the FDDI networkcausing the failure.
19 Case 1: 21 January 2010, East Rail Line Failure of Data Transmission Network Remedial MeasuresAssigning designated staff to closely monitoraudits and communicate with third-party expertAvoid peak hours auditsProhibit uploading of new software patches tothe online operating systems during traffic hoursEnsure that the online system would not be affected by implementing tighter working proceduresEstablish policy of no software audits during peak hours and operating hours as far as possibleUse security device (interlocking switch) to bar any attempt to upload new software patches to the online operating systems during traffic hours
20 Train Doors Opened when Train Stopped Short of Platform Rear End Case 2:8 January 2012East Rail LineTrain Doors Opened when Train Stopped Short of Platform Rear EndEAL Train Captain Pressing Door By-Pass Button without OCC AuthorisationOn 8 January 2012, a portion of a passenger train stopped short of the platform stopping mark.
21 Inaccurate Stopping Position Case 2: 8 January 2012, East Rail Line Train Captain Opened Doors of Train Stopping Short of Platform Rear EndWhat’s wrong?Train captain did not identify the trainstopping positionThere is a procedural bar for door openingInaccurate Stopping PositionOCC AuthorisastionEmergency activation by pressing door by-passswitch needs OCC authorisationTrain captain did not seek OCC authorisationIt is not uncommon for trains to stop in an inaccurate positionThe train doors will not be opened until the train captain has confirmed that the train is in the correct position.A door by-pass switch was provided at the control console of the cab right in front of the train captain.The original design intent was to allow evacuation in case of emergency.Authorisation of the OCC was needed before a train captain can press the door by-pass button.The train doors were opened as the train captain pressed the door by-pass switch without authorization of the OCCThat risked passengers riding on the last train compartment fall to track from a height of about 1.1mNear MissPotential safety threat of passenger falling totrack at height
22 Case 2: 8 January 2012, East Rail Line Train Captain Opened Doors of Train Stopping Short of Platform Rear EndReinforcing thecorrect procedure foroperating door by-passswitchIdentifying train stopping positionKRVigilanceProcedureImprovement MeasuresSDAidMMIInstallingstopping mark ateach platformendSwitch relocationReminder label
24 With Courtesy of MTR Corporation Limited Case 2: 8 January 2012, East Rail Line Train Captain Opened Doors of Train Stopping Short of Platform Rear EndFollow-up Actions:Refresher training programme developed to remind train captains to be vigilant in identifying the train stopping positionThe training programme also reinforced the correct procedure for operating the door by-pass switchVertical stopping mark at platform endWe recognised that the environment and the design of man-machine interface were performance shaping factors for this incidents.Half a year after the incidenb, the door by-pass switches were all relocated from the front to the back of the train captain to avoid inadvertent operation. Door bypass switch is now located at positions such that Train Captain has to stand-up and walk so as to activate the switch.The switch relocation work was completed in Jul 2012.Label was provided near door by-pass switches to further remind the train captain proper usage of the facility.With Courtesy of MTR Corporation Limited
25 Case 3: 21 October 2010, Tsuen Wan Line Breakage of Overhead Line Contact Wire In the morning of 21 October 2010,- The overhead line in a section of the Tsuen Wan Line (between Prince Edward Station and Yau Ma Tei Station) was burnt out as a result of repeated short-circuit faults.It took some time to figure out what happed and further 2.5 hours to re-connect the overhead lineAltogether, train service at Yau Ma Tei Station was suspended for 3 hours100,000 passengers were affected
26 Case 3: 21 October 2010, Tsuen Wan Line Breakage of Overhead Line Contact Wire Cause of IncidentPrimarily originated from a simple equipment faultBut successive human errors are key contributory factors to the severe service impact
27 Case 3: 21 October 2010, Tsuen Wan Line Breakage of Overhead Line Contact Wire Equipment Failure- Traction motor- Train-bourne circuit breakerHuman Errors- Communication between OCC and Train Captain- Mistake in reporting the pantograph status to the Traffic ControllerConsecutive electric short-circuit faultsOverhead line contact wire overheated and burnt outSnowball EffectHuman ErrorsProcedure of the recovery of traction power by Power System Controller- Repeated attempts to reclose the traction DC circuit breaker before asking the platform supervisor to check the pantograph status on siteOriginated from a short-circuit fault inside the traction motorLimitation of the train-bourne circuit breakertrain-borne circuit breaker damagedOverhead line traction supply circuit breaker was trippedIncident train captain was instructed to lower the pantograph to isolate the faultHe acted accordingly and the Power System Controller attempted to resume the traction power supplyIn fact, the action of the Train Captain was futile.The DC circuit breaker tripped againNobody checked the status of the pantograph on sitePower System Controller did not ask for better information about site situationHe repeatedly attempted to re-close one of the DC circuit breakers for that incident sectionThat resulted in 5 consecutive electric-short circuit faultsA fault of the traction motor alone would not have caused an incident as such. That was the outcome under a snowball effect and human errors are key contributory factors.
28 Agreed Mitigation Measures Case 3: 21 October 2010, Tsuen Wan Line Breakage of Overhead Line Contact WireAgreed Mitigation MeasuresInstall a visual indicator in the driving cab as an visual aid for the train captain to confirm the position of the pantographsReplace train-borne circuit breakers with new ones of higher current rupture capacityReview and revise the operation control procedure for closing traction supply circuit breakers to provide clear steps for operators to followWe figured out that we need to tackle two human factors issues.First, the Train Captain did not correctly report the pantograph status to the Traffic Controller.MTRCL agreed to install a visual indicator in the driving cab as an visual aid for the captain to confirm the position of the pantographsSecond, the Power System Controller attempted to reclose the traction supply circuit breakers for several times before asking the platform supervisor to check the pantograph status on site.We reviewed the operation control procedure with MTRCL.MTRCL then revised the procedure for closing traction supply circuit breakers to provide clear steps for operators to follow.
29 Restricted Manual Mode Train Operation at 20 kph Case 4: Rail Breakage Incidentsat East Rail Line and Tsuen Wan Line2011Restricted Manual Mode Train Operation at 20 kphEast Rail LineBreakage of rail as a result of crack propagating from an insulated rail joint bolt hole.JAN13Two rail breakage incidents occurred in early 2011.The first on the East Rail Line on 13 January 2011.Train services were severely affected as trains needed to travel in “restricted manual mode” at 20 kph near the affected rail section.
30 Restricted Manual Mode Train Operation at 20 kph Case 4: Rail Breakage Incidentsat East Rail Line and Tsuen Wan Line2011Restricted Manual Mode Train Operation at 20 kphTsuen Wan LineAluminothermic weld defect causing rail breakageFEB10The secondt on the Tsuen Wan Line on 10 February 2011.
31 East Rail Line Tsuen Wan Line Case 4: Rail Breakage Incidents at East Rail Line and Tsuen Wan Line (2011)Track MaintenanceEast Rail LineDating back from13 January 2011 …Track maintenancestaff had temporarilyapplied a bolt ofsmaller diameterStress concentration atbolt and bolt holeTsuen Wan LineDating back from10 February 2011 …Visual inspectionevery 3 daysTrack maintenancestaff carried out NDTonce every 2 weeksCould not detect anycrackFor the East Rail Line incident, the incident could have been avoided if a suitable size bolt was used in the first place.The entire rail network was checked and 7 IRJs with a smaller bolt were identified and replace.
32 Case 4: Rail Breakage Incidents at East Rail Line and Tsuen Wan Line (2011) RecommendationsAdoption of EN14730Site aluminothermicweld procedureQualification ofwelding personnelStandardsImprovement MeasuresRecommendationsAdoption of ISO 9712Independentexaminationcertification of NDTpersonnelStandardsA consultant reviewed the rail inspection and maintenance regime.He recommendedadopting the EN14730 standard to improve the site alumnothermic welding procedureadopting the ISO9712 standard for independent examination and certification of NDT personnel
33 ConclusionCoping with human factors incidents – a job for both regulator and operatorNo recurrence of railway incident caused by the similar human errorsIdentifying high-risk scenarios and deploy resources accordingly for necessary improvementsTargeted safeguard measures for reducing the HF risks to a level as low as reasonably practicableEffective management of railway incidents due to human error- Number of human factor incidents has been substantially contained with a steadily declining trend- No recurrence of railway incident caused by the similar human errorsEfficient utilization of resources- Focus manpower resources more efficiently on our identified high-risk scenarios- Devise very targeted safeguard measures and inspection programmes in order to reduce the risk arising from human factors to a level as low as reasonably practicable
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