appropriate automation of rail signalling systems

308 Pages·2017·6.65 MB·English

by  Christine Middleton

A A R
PPROPRIATE UTOMATION OF AIL
S S :
IGNALLING YSTEMS
A H F S
UMAN ACTORS TUDY

Nora Balfe

Thesis submitted to the University of Nottingham
for the degree of Doctor of Philosophy

July 2010
ABSTRACT

This thesis examines the effect of automation in the rail signalling environment. The
level of automation in a system can be described as ranging along a continuum from
manual control to fully autonomous automation and development of appropriate
automation for a system is likely to enhance overall system performance. Network
Rail, the company which owns, operates, and maintains the rail infrastructure in the
UK, envisions increasing levels of automation in future rail systems, but prior to this
research, little structured evaluation of current automation had been undertaken.

The research performed for this thesis set out to examine the impact of automation
on rail signalling. A rail automation model was developed to illustrate the levels of
automation present in different generations of signalling system. The research
focussed on one system in particular, the Automatic Routing System (ARS). The ARS
has been present in modern signalling centres since the late 1980s. It uses timetable
information to set routes for trains arriving on its area of control and incorporates
complex algorithms to resolve conflicts between trains.

Multiple methods were used to investigate current signalling automation. An
understanding of the signalling domain underpinned the research, and a model was
developed to illustrate the type and level of automation present in different
generations of current signalling systems. Structured observations were employed to
investigate differences in activity between individual signallers. As a part of this study,
a relationship was found between observed intervention levels and some of the trust
dimensions identified from the literature. A video archive analysis gave initial insight
into some of the issues signallers had with automation, and semi-structured
interviews carried out with signallers at their workstations built on these themes. The
interviews investigated four areas; signallers’ opinions of ARS, system performance
issues, knowledge of ARS, and interaction with ARS. Data were gathered on a wide
variety of individual issues, for example on different monitoring strategies employed,
interaction preferences, signallers’ understanding of the system and their ability to
predict it. Data on specific issues with ARS also emerged from the interviews, for
example the impact of poor programming and planning data, and the poor
competence of the system, particularly during disruption. An experiment was
performed to investigate the differences between different levels of automation under
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both normal and disrupted running. The experiment gathered quantitative data on the
effect of different levels of automation on workload and performance in addition to
eye tracking data which were used to gain insight into signaller monitoring strategies.
The results indicate that ARS does reduce workload and increase performance, and
it does so in spite of deficiencies in terms of feedback to the signaller. This lack of
feedback makes it difficult for the signaller to understand and predict the automation
and, hence, creates difficulties for the operator. In addition, the methods for
controlling ARS are limited and it can be difficult for the signallers to work
cooperatively with the system.

Principles of good automation were identified from the literature and
recommendations based on these and the findings of the research were developed
for future signalling automation systems. These highlighted the importance of
improving feedback from ARS and the ability of the signaller to direct the system. It is
anticipated that these improvements would allow the signaller and the automation to
work more closely together in order to maximise overall system performance. The
principles of automation are intended as a generic guidance tool and their application
is not confined to rail signalling. There may also be wider implications from the
research such as the influence of operators’ ability to understand and predict
automation in automation use, and the existence of different types of monitoring
behaviour.
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ACKNOWLEDGEMENTS

My thanks first go to John Wilson and Sarah Sharples for their excellent supervision
and support throughout the research, and for complementing each other in the advice
they gave me throughout. I would also like to thank Theresa Clarke for her guidance
and support, and for the funding!

Thanks to all those who assisted in the research, in particular Bob Muffett and John
Robinson, without whom signalling would still remain a confusing tangle of symbols,
lines, colours and rules. In addition, thanks to all the participants in the studies,
particularly the signallers who gave up their time to explain signalling and answer my
questions. Thanks also for the endless cups of tea offered, which unfortunately I don’t
drink.

Many thanks to Team Ergo, both for the professional and not so professional support
offered. In particular the other students whose willingness to discuss their
experiences and collective trauma kept me motivated and sane – Alex, Tom, Pedro
and Yassi. Also those in the noisy bay at Network Rail: Fiona, Justin, and Philippa.
Thanks for the lunch and chocolate.

Thanks to my family and friends for helping me have a life outside my PhD. Fiona
deserves special mention for being kind enough to listen to my complaints and still
find time to proof read for me. And finally, my thanks to Simon, particularly for letting
me bore the pants off him with railway talk when no-one else would listen.
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LIST OF CONTENTS
CHAPTER 1: INTRODUCTION.........................................................................................................1
1.1 CHAPTER OVERVIEW...............................................................................................................1
1.2 BACKGROUND.........................................................................................................................1
1.3 AIMS AND OBJECTIVES............................................................................................................2
1.4 RESEARCH APPROACH.............................................................................................................3
1.5 SIGNALLING ENVIRONMENT....................................................................................................7
1.6 THESIS STRUCTURE...............................................................................................................10
1.7 CHAPTER SUMMARY..............................................................................................................10
CHAPTER 2: AUTOMATION AND HUMAN FACTORS.............................................................12
2.1 CHAPTER OVERVIEW.............................................................................................................12
2.2 INTRODUCTION......................................................................................................................12
2.3 OVERVIEW OF AUTOMATION.................................................................................................13
2.4 LEVELS OF AUTOMATION......................................................................................................16
2.5 HUMAN FACTORS CONCERNS................................................................................................20
2.5.1 Trust in Automation.......................................................................................................21
2.5.2 Situation Awareness and Automation............................................................................25
2.5.3 Workload and Automation.............................................................................................29
2.5.4 Monitoring of Automation.............................................................................................32
2.6 DESIGN OF AUTOMATED SYSTEMS........................................................................................37
2.7 PRINCIPLES OF AUTOMATION................................................................................................38
2.7.1 Reliable..........................................................................................................................39
2.7.2 Competent......................................................................................................................39
2.7.3 Visible............................................................................................................................39
2.7.4 Observable....................................................................................................................40
2.7.5 Understandable.............................................................................................................40
2.7.6 Directable......................................................................................................................41
2.7.7 Robust............................................................................................................................41
2.7.8 Accountable...................................................................................................................42
2.7.9 Error Resistant..............................................................................................................42
2.7.10 Error Tolerant...............................................................................................................43
2.7.11 Proactive Control..........................................................................................................43
2.7.12 Skill Degradation..........................................................................................................44
2.7.13 Summary........................................................................................................................44
2.8 CONCLUSIONS........................................................................................................................44
2.9 CHAPTER SUMMARY..............................................................................................................46

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CHAPTER 3: RAIL AUTOMATION MODEL................................................................................47
3.1 CHAPTER OVERVIEW.............................................................................................................47
3.2 INTRODUCTION......................................................................................................................47
3.3 METHOD................................................................................................................................50
3.3.1 Participants...................................................................................................................50
3.3.2 Apparatus......................................................................................................................50
3.3.3 Procedure......................................................................................................................50
3.4 RESULTS................................................................................................................................51
3.5 DISCUSSION...........................................................................................................................54
3.5.1 Information Acquisition.................................................................................................54
3.5.2 Information Analysis.....................................................................................................55
3.5.3 Decision and Action Selection.......................................................................................55
3.5.4 Action Implementation..................................................................................................56
3.5.5 Rail Automation Graph.................................................................................................56
3.6 CHAPTER SUMMARY..............................................................................................................58
CHAPTER 4: STRUCTURED OBSERVATIONS OF IECC SIGNALLERS...............................59
4.1 CHAPTER OVERVIEW.............................................................................................................59
4.2 INTRODUCTION......................................................................................................................59
4.3 METHOD................................................................................................................................63
4.3.1 Participants...................................................................................................................63
4.3.2 Apparatus......................................................................................................................63
4.3.3 Design............................................................................................................................64
4.3.4 Pilot...............................................................................................................................70
4.3.5 Procedure......................................................................................................................71
4.4 RESULTS................................................................................................................................72
4.4.1 Overall Results..............................................................................................................72
4.4.2 Monitoring.....................................................................................................................76
4.4.3 Intervention...................................................................................................................77
4.4.4 Planning........................................................................................................................78
4.4.5 Communications............................................................................................................79
4.4.6 Quiet Time.....................................................................................................................80
4.4.7 Closed Circuit Television Operation.............................................................................81
4.4.8 Trust..............................................................................................................................82
4.4.9 Inter-Observer Reliability.............................................................................................86
4.5 DISCUSSION...........................................................................................................................87
4.5.1 Monitoring.....................................................................................................................87
4.5.2 Intervention...................................................................................................................89
4.5.3 Planning........................................................................................................................90
4.5.4 Communications............................................................................................................91
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4.5.5 Quiet Time.....................................................................................................................91
4.5.6 Closed Circuit Television Operation.............................................................................93
4.5.7 Trust..............................................................................................................................93
4.5.8 Discussion of Method....................................................................................................98
4.6 CONCLUSIONS......................................................................................................................100
4.7 CHAPTER SUMMARY............................................................................................................101
CHAPTER 5: SIGNALLER INTERVIEWS...................................................................................102
5.1 CHAPTER OVERVIEW...........................................................................................................102
5.2 INTRODUCTION....................................................................................................................102
5.3 VIDEO ARCHIVE ANALYSIS METHOD..................................................................................106
5.3.1 Participants.................................................................................................................106
5.3.2 Apparatus....................................................................................................................106
5.3.3 Procedure....................................................................................................................107
5.4 SEMI-STRUCTURED INTERVIEW METHOD............................................................................107
5.4.1 Participants.................................................................................................................107
5.4.2 Apparatus....................................................................................................................107
5.4.3 Procedure....................................................................................................................107
5.5 RESULTS..............................................................................................................................108
5.6 DISCUSSION.........................................................................................................................110
5.6.1 General Opinion of Automatic Route Setting..............................................................110
5.6.2 System Performance Issues.........................................................................................114
5.6.3 Knowledge of Automatic Route Setting.......................................................................125
5.6.4 Interaction with Automatic Route Setting....................................................................133
5.6.5 Discussion of Method..................................................................................................147
5.7 CONCLUSIONS......................................................................................................................148
5.8 CHAPTER SUMMARY............................................................................................................149
CHAPTER 6: LEVEL OF AUTOMATION EXPERIMENT........................................................151
6.1 CHAPTER OVERVIEW...........................................................................................................151
6.2 INTRODUCTION....................................................................................................................151
6.3 METHOD..............................................................................................................................154
6.3.1 Participants.................................................................................................................154
6.3.2 Apparatus....................................................................................................................155
6.3.3 Design..........................................................................................................................159
6.3.4 Pilot.............................................................................................................................162
6.3.5 Procedure....................................................................................................................168
6.4 RESULTS..............................................................................................................................171
6.4.1 Workload.....................................................................................................................171
6.4.2 Performance................................................................................................................172
6.4.3 Behaviour Observation................................................................................................174
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6.4.4 Eye Tracking...............................................................................................................181
6.4.5 Situation Awareness....................................................................................................186
6.5 DISCUSSION.........................................................................................................................186
6.5.1 Workload.....................................................................................................................186
6.5.2 Performance................................................................................................................187
6.5.3 Behaviour Observation................................................................................................188
6.5.4 Eye Tracking...............................................................................................................190
6.5.5 Situation Awareness....................................................................................................191
6.5.6 Discussion of Method..................................................................................................191
6.6 CONCLUSIONS......................................................................................................................194
6.7 CHAPTER SUMMARY............................................................................................................195
CHAPTER 7: GENERAL DISCUSSION........................................................................................196
7.1 CHAPTER OVERVIEW...........................................................................................................196
7.2 INTRODUCTION....................................................................................................................196
7.3 DISCUSSION OF RESEARCH APPROACH................................................................................197
7.4 DISCUSSION OF RESEARCH FINDINGS..................................................................................200
7.4.1 Trust............................................................................................................................200
7.4.2 Situation Awareness....................................................................................................201
7.4.3 Workload.....................................................................................................................202
7.4.4 Monitoring...................................................................................................................204
7.4.5 Performance................................................................................................................205
7.4.6 Directability................................................................................................................206
7.4.7 Organisational Issues..................................................................................................207
7.4.8 Summary......................................................................................................................208
7.5 RECOMMENDATIONS FOR FUTURE AUTOMATED SIGNALLING SYSTEMS.............................210
7.5.1 Reliable........................................................................................................................210
7.5.2 Competent....................................................................................................................210
7.5.3 Visible..........................................................................................................................211
7.5.4 Observable..................................................................................................................211
7.5.5 Understandable...........................................................................................................212
7.5.6 Directable....................................................................................................................212
7.5.7 Robust..........................................................................................................................213
7.5.8 Accountable.................................................................................................................214
7.5.9 Error Resistant............................................................................................................214
7.5.10 Error Tolerant.............................................................................................................214
7.5.11 Proactive Control........................................................................................................215
7.5.12 Skill Degradation........................................................................................................216
7.6 LIMITATIONS OF THE RESEARCH..........................................................................................217
7.7 CHAPTER SUMMARY............................................................................................................217
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CHAPTER 8: CONCLUSIONS........................................................................................................219
8.1 CHAPTER OVERVIEW...........................................................................................................219
8.2 RECOMMENDATIONS...........................................................................................................219
8.3 IMPACT OF THE RESEARCH..................................................................................................220
8.4 FUTURE WORK....................................................................................................................222
8.5 SUMMARY...........................................................................................................................223
REFERENCES...................................................................................................................................224
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LIST OF FIGURES
FIGURE 1-1: CONCEPTUAL FRAMEWORK..................................................................................................4
FIGURE 1-2: RESEARCH FRAMEWORK.......................................................................................................5
FIGURE 1-3: EXAMPLES OF SIGNALLING SYSTEMS....................................................................................8
FIGURE 2-1: POSITION OF THE LITERATURE REVIEW IN THE RESEARCH FRAMEWORK............................13
FIGURE 2-2: LEVELS OF AUTOMATION (BILLINGS, 1991)........................................................................16
FIGURE 2-3: LEVELS OF AUTOMATION (ENDSLEY & KIRIS, 1995)..........................................................17
FIGURE 2-4: HUMAN INFORMATION PROCESSING (WICKENS & CARSWELL, 1997, P. 91).......................18
FIGURE 2-5: HUMAN INFORMATION PROCESSING (PARASURAMAN ET AL., 2000)...................................18
FIGURE 2-6: LEVELS OF AUTOMATION (SHERIDAN, 1998)......................................................................19
FIGURE 2-7: GRAPHICAL REPRESENTATION OF LEVELS OF AUTOMATION (SHERIDAN, 1998).................20
FIGURE 2-8: PURPOSES OF MENTAL MODELS (ROUSE & MORRIS, 1986, P. 351).....................................23
FIGURE 2-9: OPERATOR MONITORING MODEL (VICENTE ET AL., 2004)..................................................35
FIGURE 3-1: POSITION OF RAIL AUTOMATION MODEL IN THE RESEARCH FRAMEWORK.........................48
FIGURE 3-2: MODEL OF LEVELS OF RAIL SIGNALLING AUTOMATION.....................................................57
FIGURE 4-1: POSITION OF THE OBSERVATION STUDY AND TRUST QUESTIONNAIRE IN THE RESEARCH
FRAMEWORK................................................................................................................................60
FIGURE 4-2: STUDY DESIGN....................................................................................................................64
FIGURE 4-3: NEWCASTLE WORKSTATION...............................................................................................66
FIGURE 4-4: DARLINGTON WORKSTATION..............................................................................................66
FIGURE 4-5: ILFORD WORKSTATION.......................................................................................................67
FIGURE 4-6: SHENFIELD WORKSTATION.................................................................................................67
FIGURE 4-7: OBSERVATION DATA...........................................................................................................73
FIGURE 4-8: RESULTS BY DISRUPTION LEVELS.......................................................................................75
FIGURE 4-9: MONITORING RESULTS........................................................................................................76
FIGURE 4-10: INTERVENTION RESULTS...................................................................................................77
FIGURE 4-11: PLANNING RESULTS..........................................................................................................78
FIGURE 4-12: COMMUNICATIONS RESULTS.............................................................................................80
FIGURE 4-13: QUIET TIME RESULTS........................................................................................................81
FIGURE 4-14: CCTV RESULTS................................................................................................................81
FIGURE 4-15: TRUST QUESTIONNAIRE RESULTS.....................................................................................82
FIGURE 4-16: SIGNIFICANT DIFFERENCES FOR INTERVENTION GROUPS..................................................85
FIGURE 4-17: SIGNIFICANT DIFFERENCES FOR QUIET TIME GROUPS......................................................86
FIGURE 4-18: INTER-OBSERVER COMPARISON........................................................................................87
FIGURE 5-1: POSITION OF INTERVIEWS, VIDEO ARCHIVE ANALYSIS, AND PARTICIPANT OBSERVATION IN
THE RESEARCH FRAMEWORK.....................................................................................................103
FIGURE 5-2: QUALITATIVE DATA THEMES............................................................................................106
FIGURE 5-3: PINK AND BLUE TRAIN HEADCODES.................................................................................118
FIGURE 6-1: POSITION OF THE LEVEL OF AUTOMATION EXPERIMENT IN THE RESEARCH FRAMEWORK 152
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