Improving incident analysis

in the Dutch railway sector

Mark Dabekaussen (Tebodin Consultants & Engineers)

Linda Wright (ProRail)

Tjerk van der Schaaf (Eindhoven University of Technology)

Slide: 2

Overview

• What is a SPAD?

• Research goal

• SPAD analysis methods

• Results

• Discussion

• Study constraints

• Conclusions

Slide: 3

What is a SPAD?A Signal Passed at Danger incidentoccurs when a train driver passes ared signal without permission

Bron: IVW – trendanalyse 2004

Nu

mb

er

of

SP

AD

’s

Year

Slide: 4

Research goalTo determine whether a more comprehensive analysis approach would provide additional insight on the root-causes underlying SPAD incidents.

- Existing analysis method: Bow-tie

- Alternate analysis method: PRISMA

Slide: 5

SPAD bow-tie model (1)• Developed to specifically investigate

relationships between causes and consequences of SPAD’s

• 10 main causal factors (63 sub-cat’s)

• Factors similar to those reported in other countries (including UK)

• 10 possible consequences

• Possible to include multiple causes and multiple consequences!

Slide: 6

SPAD bow-tie model (2)

SPAD Incident

Previous signal perception

Braking operation

Network Control process

Communication

Expectations

Information processing

Driver actions

Network Controller actions

Contributing factors

Signal perception

No injuries

Material damage

Minor injuries personneland/or passengers

Serious injuries personneland/or passengers

Death to personneland/or passengers

Further escalation – fire, explosion etc.

Collision – damaged infrastructure

Collision – level crossing

Only financial consequences

Derailment

Slide: 7

PRISMABasic components:

Analysis: Causal trees

Result: Root-causes

Classification: Eindhoven Classification Model

Result: Profile of root causes

Countermeasures: Classification / action matrix

Output: Appropriate countermeasure(s)

Slide: 8

Requirements of a Taxonomy

Taxonomic criteriaSPAD Bow-tie

modelPRISMA

1. Underlying theory

2. Tech./org./human factors

3. Reliable 4. Comprehensive 5. Quantitative 6. Recommendations 7. Differentiation

Slide: 9

Method of Analysis (1)Analysis using the Bow-tie modelAim: to translate bow-tie causes

into applicable PRISMA categories

Method: algorithm constructed by bow-tie analyst

Dataset: 69 incidents selected from 2003 incident set

Reliability: inter-rater reliability trials for both data and algorithm

Slide: 10

Method of Analysis (2)Analysis using the PRISMA method

Aim: examination of effectiveness of analysis

Method: reanalysis of data using causal-trees & PRISMA classification

Dataset: same 69 incidents selected from 2003 incident set

Reliability: inter-rater reliability trial of analysis and classification

Slide: 11

Results

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Technical Organisational Staff Customer &Public

Unclassified

PRISMA Category

Per

cen

tag

e

Bow-tie analysis PRISMA analysis

**

*

* Statistically Significant difference

Slide: 12

Discussion (1)• Significant differences in the types of

root-causes being found using PRISMA vs. SPAD Bow-tie model

• Not all information being used in analysis (i.e. focus on “active” rather than “latent” errors)

Slide: 13

Discussion (2)• Bow-tie analyst admitted to further

interpretation of data

• Difference in complexity of analysis- supported by tentative results of 3rd study

Causal factor

Causal factor

SPAD Bow-tieanalysis

Causal factor

Root cause

PRISMA analysis

Root cause

Root cause

Slide: 14

Study constraints• No examination of recovery factors

• No examination of specific consequences

• Limited information in dossiers, did not enable a full PRISMA analysis

• Accuracy of information in dossiers

Slide: 15

Conclusions• Current SPAD analysis process is

not as effective as possible

• Primary focus on staff and little focus on org./tech. factors

• Including multiple causes in incident analysis is an insufficient qualification for effective analysis

Underlying taxonomy must meet minimum set of criteria

Slide: 16

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