International Railway Safety Conference, September 28 th 2009 Slide 1

Railway Safety and Security – Two Sides of the Same Coin ? !

L. Schnieder; E. Schnieder; T. Ständer

• Introduction• The role of communication• Motivation for terminology work

• Methodical foundation• The metamodel of a linguistic sign

• Application• Formalization of the risk concept

• Formalization of the safety concept

• Formalization of the security concept

• Conclusion

Slide 3International Railway Safety Conference, September 28 th 2009

memory

mental lexicon

event schemas (scripts)

objectschemas

formulation

concept-ualization

-interpretation

transmission

mentalrepresentation

lexicalidentification

memory schemas

RECEIVER

recognition

syntactical schemas

phonetic schemas

articulationperception

sensory schemas

motor schemas

morphologicallevel

syntacticlevel

semanticlevel

pragmaticlevel

cognitivelevel

phonologicallevel

physicallevel

TRANSMITTER

IntroductionPitfalls of communication

Slide 4International Railway Safety Conference, September 28 th 2009

A formalized concept model helps to overcome lexical ambiguities!

A concept‘s designation is just the tip of the iceberg. What really matters is underneath the watersurface . . .

The meaning of a concept is often tacitly assumed:

intension extension relations

IntroductionThe importance of semantics

Slide 5International Railway Safety Conference, September 28 th 2009

semantic vagueness: terminological definitions are imprecise What characteristics describe the severity of a minor or major injury?

Duration of clinical treatment [hours] Time of convalescence [weeks] Reversibility of injury [boolean] Regain of full capacity to work [boolean]

ambiguity: different words have multiple meanings „argument“ process or result? „specification“ process or result?

inconsistency: standards are contradictory "fault" expressed by IEC 61508-4 “fault” expressed by IEC 60050(191)

October, 22nd 1895: Montparnasse train accident

General situation: language use in railway engineering is blurry there is a lack of a consistent and harmonized terminology

context dependence: standards are contradictory “signal" in communications engineering “signal” in railway engineering

IntroductionMotivation – Status quo of terminology use

Slide 6International Railway Safety Conference, September 28 th 2009

Methodical foundationMetamodel of a linguistic sign

linguistic sign

signifier (concept

designation)

signified(concept)

concept relations

extensionintension

linguistic variety

concept definition

1

1

1

n

1

1

mn

m n

Slide 7International Railway Safety Conference, September 28 th 2009

Methodical foundationRelations within a concept system

concept relation

pragmatic concept relation

hierarchical

Taxonymy(abstraction)

partonymy/meronymy

dynamic

antonymytemporal relation

causal relation

non-hierarchical

sequentialconcurrent

concept

comple-mentarity

Slide 8International Railway Safety Conference, September 28 th 2009

ApplicationRisk as a concept system

Damage

distribution of extent of damage

E(D) = MED(P(D))

distribution of frequency of occurence

E(T) = MED(P(T))

Risk

E(R) = E(D) x E(T)

11 1…* 1…*

environmental harm human harm

major injury fatalityminor injury

commercial harm / financial detriment

Slide 9International Railway Safety Conference, September 28 th 2009

ApplicationRisk as a concept system

initial risk

residualrisk

tolerable risk

necessaryrisk reduction

achievedrisk reduction

Slide 10International Railway Safety Conference, September 28 th 2009

ApplicationFormalization of the safety terminology of ISO/IEC Guide 51

char

acte

rist

ic(p

etrin

et)

pro

per

ty(U

ML

clas

s di

agra

m)

qu

anti

ty(U

ML

clas

s di

agra

m)

unimpaired assets

Harmful event(3.13)

harm(3.1)

hazard(3.3)

hazardous events(3.12)

potential hazard

risk (3.2)

haza

rdou

s

situa

tion

probability distribution function for loss frequency

probability distribution function

for loss severity

risk

probability distribution of

hazardous events

hazard rate

Slide 11International Railway Safety Conference, September 28 th 2009

ApplicationFormalization of the security terminology of the ISO/IEC Draft Guide

 

char

acte

rist

ic(p

etrin

et)

pro

per

ty(U

ML

clas

s di

agra

m)

qu

anti

ty(U

ML

clas

s di

agra

m)

probability distribution function for loss frequency

probability distribution function

for loss severity

risk

unwanted incident (emergency?)

harm (2.7)disaster (2.3)

threatening event(attack)

potential threat

risk

probability distribution of

threatening events

probability of threatining event

threat

unimpaired assets

thre

aten

ing

situa

tion

system boundary

Slide 12International Railway Safety Conference, September 28 th 2009

ApplicationIterative process of risk assessment and risk reduction (risk control)

system definition

hazard identification

risk estimation

risk evaluation

protective measures in design phase

protective measures in

operation phase

tolerable risk

intended use

identified hazards

initialrisk

actual risk

reduction

necessary risk reduction

risk reduction

risk analysis

risk treatment

risk assessment

residualrisk

unimpaired asset

(exposure profile)

Slide 14International Railway Safety Conference, September 28 th 2009

Tack för uppmärksamheten!

Thank you for your attention!