Risk Analysis for Truck Transportation of Risk Analysis for Truck - - PowerPoint PPT Presentation

SAND2010-5995C

Risk Analysis for Truck Transportation of Risk Analysis for Truck Transportation of High Consequence Cargo High Consequence Cargo g q g g q g

Bob Waters

S di N ti l L b t i Sandia National Laboratories Workshop on Risk Assessment and Safety Decision Making under Uncertainty g y September 21-22, 2010

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Sandia National Laboratories is a multi-program laboratory manager and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin company, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000

Comparing fixed facilities to transportation Co pa g ed ac t es to t a spo tat o

The “chicken ranch” controls everything they can to drive down risk

– Control environment, work processes, work pace, and workers

The “egg haulers” drive the State and US highways with high kinetic d l t ll bl i k energy and less-controllable risks

– Other drivers (beginners, impaired, distracted, etc.) – Other vehicles (tankers, hazmat, super-heavies) Road environments (bridges/tunnels/abutments/construction) – Road environments (bridges/tunnels/abutments/construction) – Degraded weather

Lots of uncertainty in the type of transportation accidents to plan for

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Begin with the End in Mind eg t t e d d

Keep cargo safe during credible worst-case accidents

What is credible?

Depends on the person Often use a low likelihood of occurrence

• 10-6/yr – commonly assumed
• Called Design Basis Accidents (DBA)

Resulting forces accident

What is safe?

Demonstrated safe environments through testing and analysis Resulting forces accident environments

How to “keep cargo safe”

Controls mitigate accidents environments to demonstrated safe cargo environments

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• Tractor and trailer, cargo restraints, operations

Building the Technical Case for “Credible” u d g t e ec ca Case o C ed b e

What kinds of insults are a concern?

– Mechanical – crash breaks eggs – Thermal – fire cooks eggs – Electrical – energy “fries” eggs Combined en ironments ca se broken scrambled fried eggs! – Combined environments – cause broken, scrambled, fried eggs! – …

Let’s focus on mechanical insults Let s focus on mechanical insults

– Pay attention to assumptions, extensions, limitations in the details – Pay attention to narrowing of focus as we focus in on quantitative solutions

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Dealing with the reality of limited data ea g t t e ea ty o ted data

“Egg haulers” have too few accidents & miles for meaningful statistics

⇒ Assume we’re no worse than the industry average and use national databases ⇒ Determine the accident-per-mile rate

No national accident databases exist for high-energy crashes, but trucks No national accident databases exist for high energy crashes, but trucks involved in fatal accidents (TIFA) are tracked

⇒ Assume TIFA accidents encompass high-energy accidents ⇒ Identify the most severe TIFA accidents for investigation

Details of severe accidents are buried in police accident reports

⇒ Analyze the ~1500 worst TIFA accidents to infer worst environments

Organize TIFA accidents into analyzable groups

⇒ Bin accidents into cardinal impact directions ⇒ Determine equivalent insult to egg truck

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Unifying metric for analyzing crashes U y g et c o a a y g c as es

Peak Contact Velocity (PCV) in MPH is the maximum change in velocity that would be experienced by the cargo due to an accident.

f – Based on conservation of momentum – Assumes plastic deformations , (e.g., hard surface) Egg Truck pact Object unyielding Impact Object (e.g., train) Egg Truck

65 MPH 55 MPH

Imp E

Case 1 – Head-on crash Case 2 – Side Impact crash

55 MPH 6

Results: 10-6/yr Design Basis Accidents esu ts 0 /y es g as s cc de ts

1.E-03 1.E-04 eding PCV 1.E-05 hood of Excee

DBA

1.E-07 1.E-06 Likeli

DBA

10 20 30 40 50 60 70 80 Peak Contact Velocity - PCV (MPH)

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Testing to Find DBA Forces est g to d

• ces
• In 2002 we crashed an “egg truck” into a hard unyielding surface at 65 MPH
• In 2002, we crashed an egg truck into a hard unyielding surface at 65 MPH

to measure truck and cargo accelerations

• Results provided the environments to design restraints and controls

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My Lessons Learned y esso s ea ed

“In theory, there is no difference between theory and practice; In practice, there is.” – Yogi Berra g

• Real world is dirty, messy, incomplete, unknown
• We must make assumptions, use limited data & imperfect models

“It's not so much what you don't know that can hurt you, it's what you think you know that ain't so.” – Will Rogers

• Reasonable assumptions can lead to reasonable analyses
• Tenuous assumptions, data or analyzes may be worse than no analysis

“All happy families resemble one another, each unhappy family is unhappy in its own way.” – Leo Tolstoy

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