Major Rail Occurrence

ForumSydney – 28-29 April 2015

Tony SimesManager - Rail

ATSB

Rail Accident Investigations –The ATSB Approach

• Accident Investigations

– Aviation

– Marine

– Rail

• Research

– Aviation / Marine / Rail

Australian Transport Safety Bureau (ATSB)

• ATSB Rail Investigators

– Perth

– Adelaide

– Canberra

• Agreements with

– OTSI (Sydney)

– CITS (Melbourne)

• ATSB Rail jurisdiction

– NSW

– Vic

– SA

– NT

– Tas

– WA (DIRN)

– QLD (DIRN)

• Punitive (breaches of law)

– Criminal / Civil

– Regulatory (in some cases)

• Just Cause (recognises that errors occur)

– Coronial (mostly)

– Internal organisation (preferably)

• No Blame

– ATSB

Investigation Types

• Not only ‘What’ happened, but ‘Why’

– Why did it occur

– Why did people behave the way they did

– Why did the environment/system allow it

• What factors and issues contributed to the accident

• How can the system be made more error tolerant

ATSB Investigation Analysis Model

Risk Controls

(Recovery)

Risk Controls

(Recovery)

Risk Controls

(Preventive)

Local

Conditions

Individual

Actions

Technical

Events

Production

Goals

Accident

Organisational

Influences

Incident

• Described in terms of production goals and risk controls

• An accidents and incidents are deviations from the normal production path

• Preventative risk controls– Minimise the likelihood of deviations from the normal path

• Recovery risk controls– Minimise the severity of incidents and aim to prevent accidents

when deviations occur

• An accident occurs

where there is a failure

or lack of risk controls

ATSB Investigation Analysis Model

• Safety factor:– an event or condition that

increases safety risk.

• Safety issue:– a safety factor that is a

characteristic of an organisation

or a system, rather than a

characteristic of a specific

individual, or characteristic of an

operational environment at a

specific point in time.

Organisational Influences

(What could have been in place to prevent problems

with the risk controls?)

Risk Controls

(What could have been in place at the operational level

to reduce the likelihood or severity of problems?)

Local Conditions

(What aspects of the local environment may have

influenced the individual actions /

technical problems?)

Individual Actions

(What individual actions increased safety risk?)

Pro

du

ctio

n p

ath

Safety

issues

Safety

indicators

Inve

stig

atio

n p

ath

Occurrence Events(including technical problems)

(What events best describe the occurrence?)

Safety

Issues

• Notification

• Site examination, collection/protection of evidence

• Sequence of Events

– What happened

– When did it happen

Investigation process

Derailment – Bates, SA

• At about 0650, on 19 April 2008

• Freight train 5PS6 derailed near Bates (SA)

about 220 km west of Tarcoola.

• Two locomotives (NR90 and NR51) hauling

44 wagons (15 multiple-unit wagons).

• The train was 1770 m long and weighed a

total of 3886 t.

• Travelling around a curve at about 80 km/h

• Locomotive drivers recalled hearing ‘crack, crack, crack’

• The driver eased off the throttle before noticing a

reduction of brake pipe pressure

• Train brakes automatically applied and 5PS6 came to a

stop

• Train had derailed and a significant portion of track had

been destroyed

• Dangerous goods (resin solution and various chemicals)

• Exclusion zone around the derailment site until an

appropriate assessment could be conducted by

hazardous materials assessors.

Sequence

• Contributing factors

vs. causal factors

• Determine which events and conditions were safety

factors, with an emphasis on determining the

contributing safety factors and safety issues.

Safety factor analysis

• Standard of proof

– Probably or likely

– Do not want to limit learning

potential by requiring beyond

reasonable doubt.

• Standard of evidence

– Quantity and quality

• is it:

– a contributing safety factor (existence plus influence),

– another safety factor of interest (existence plus importance)

– or of no consequence to the investigation.

Testing possible safety factors

What the ATSB found

• The rail had fractured through an unused bolt-hole in the web of the rail.

High cycle

fatigue

Progressive

overload

Final

fracture

Fatigue

origin

Initial fractureSecondary fracture

Direction of train 5PS6

Direction of train 5MP5

Weld

Contributing factors

• Crack at unused bolt-hole

– Initial crack was almost 20 mm in length

– Consistent with high cycle fatigue cracking

– Had existed for some time

• Ultrasonic testing 3 days earlier

– Showed an echo pattern that was consistent

with a bolt-hole crack

– Was not observed by the test vehicle operator

– Therefore not flagged for closer examination.

Figure 4: Broken rail

• Individual actions

• Local conditions

Organisational Influences

(What could have been in place to prevent problems

with the risk controls?)

Risk Controls

(What could have been in place at the operational level

to reduce the likelihood or severity of problems?)

Local Conditions

(What aspects of the local environment may have

influenced the individual actions /

technical problems?)

Individual Actions

(What individual actions increased safety risk?)

Pro

du

ctio

n p

ath

Safety

issues

Safety

indicators

Inve

stig

atio

n p

ath

Occurrence Events(including technical problems)

(What events best describe the occurrence?)

Contributing factors

• Theoretical finite element, crack initiation

and crack growth analysis

– Unused bolt-holes act as a stress concentrator

increasing the risk of a fatigue crack.

– Likely that any fatigue crack originating from a

bolt hole will increase in size until the inevitable

failure

• Metallurgical examination

– microstructural transition between the weld

heat affected zone and the original metal

coincided with the fatigue origin at the bolt-

hole.

– This transition was likely to have acted as a

localised stress concentrator at the bolt-hole.

Figure 4: Broken rail

• Individual actions

• Local conditions

Organisational Influences

(What could have been in place to prevent problems

with the risk controls?)

Risk Controls

(What could have been in place at the operational level

to reduce the likelihood or severity of problems?)

Local Conditions

(What aspects of the local environment may have

influenced the individual actions /

technical problems?)

Individual Actions

(What individual actions increased safety risk?)

Pro

du

ctio

n p

ath

Safety

issues

Safety

indicators

Inve

stig

atio

n p

ath

Occurrence Events(including technical problems)

(What events best describe the occurrence?)

Safety Issues

• Contributing safety issues

– The process for identifying potential rail

defects was limited by the ultrasonic test

vehicle operator’s ability to detect and assess

the echo patterns correctly.

– The CoP did not categorise bolt-hole cracks

as defects requiring action unless they

exceeded 20 mm in length

– The CoP did not recognise the relationship

between heat affected metal and stress

concentration when specifying how far a bolt-

hole should be from the rail ends before

welding.

• Organisational

influences

• Risk Controls

Organisational Influences

(What could have been in place to prevent problems

with the risk controls?)

Risk Controls

(What could have been in place at the operational level

to reduce the likelihood or severity of problems?)

Local Conditions

(What aspects of the local environment may have

influenced the individual actions /

technical problems?)

Individual Actions

(What individual actions increased safety risk?)

Pro

du

ctio

n p

ath

Safety

issues

Safety

indicators

Inve

stig

atio

n p

ath

Occurrence Events(including technical problems)

(What events best describe the occurrence?)

• How do we address

the safety issues

– Determine the risk level associated with any verified

safety issues.

– Prioritise actions based on risk profile

• ATSB : communicating safety issues to relevant organisations.

Safety actions

• Identify gaps or

weaknesses.

• Reality check

• Make sure all of the

findings make sense.

– Can be conducted progressively throughout the investigation

Review

What has been done

• Review of standards

– all bolt-hole cracks are recorded as defects and require removal,

irrespective of the crack size.

• Further development of the ultrasonic testing process

– Reduce reliance on the operator to recognise defects

• software solution to identify ultrasonic reflection patterns

– Re-analysis of data to identify defects that

may have been missed

Conclusion

• Identify ‘What’ happened, but also ask the

question ‘Why’ did it happen.

– Why did people behaved the way they did

– Why did the environment allow it to occur

• Adopt a framework designed to encourage

quality analysis techniques

• What factors contributed to the incident

• Aim is to enhance safety, not to apportion

blame or liability.

• Look for:

– Organisational influences

– Risk control measures

Thankyou