Safety (C01)_pdf-notes_201112100749

Safety (C01)_pdf-notes_201112100749 - Week 11 Lecture B...

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Unformatted text preview: Week 11 Lecture B SAFE IS NOT A FOUR LETTER WORD Week 11 Lecture B ENG 1P03 2011 1 Which of the following are mentioned in the PEO Code of Ethics? A. B. C. D. E. Health Safety The Environment All of the above None of the above Week 11 Lecture B ENG 1P03 2011 2 Introduction to Health & Safety • “Regard the practitioner’s duty to the public welfare a paramount” • “Engineers may be responsible for managing situations that contain potential danger for those present or those who will occupy or use the result of the work.” • Failure to correct potentially dangerous situations or failure to follow codes and standards is professional misconduct. Week 11 Lecture B ENG 1P03 2011 3 Safety in Design • Design decision: decide between two passenger car brake systems: A. Lower cost; less safe B. Higher cost; more safe • Safety measured by stopping distance • Stopping distance correlates strongly with severity of accident and injury Week 11 Lecture B ENG 1P03 2011 4 Questions 1. Is it ethical to recommend the lower cost system? 2. If yes, how do you reconcile this with the Professional Engineer’s duty to the public? 3. If no, are all the Professional Engineers who design less safe products acting unethically? Week 11 Lecture B ENG 1P03 2011 5 Ford Pinto Week 11 Lecture B ENG 1P03 2011 6 The Context • The Japanese vs. the Americans • No American car with less than six cylinders • Should or should not Ford compete with imports for the sub-compact market? Week 11 Lecture B ENG 1P03 2011 7 Lee Iacocca • Born to Italian immigrants • Trained as an industrial engineer • President of Ford • CEO of Chrysler Week 11 Lecture B ENG 1P03 2011 8 The Directive • “The Pinto was not weigh an ounce over 2,000 pounds and not cost a cent over $2,000.” Week 11 Lecture B ENG 1P03 2011 9 Week 11 Lecture B ENG 1P03 2011 10 Ford Pinto Controversies Week 11 Lecture B ENG 1P03 2011 11 Cost-Benefit Analysis • Cost-Benefit Analysis – Costs: $137,000,000 • Estimated as the costs of a production fix to all similarly designed cars and trucks with the gas tank aft of the axle (12,500,000 vehicles × $11/vehicle) – Benefits: $49,530,000 • Estimated as the savings from preventing (180 projected deaths × $200,000/death) + (180 projected burn injuries × $67,000/injury) + (2,100 burned cars × $700/car) • In 1970, the value of a human life was deemed to be approximately $200,000 as a “cost to society” for each fatality by the National Highway Traffic Safety Association (NHTSA, an agency of the U.S. government). • One Ford executive was quoted as saying – “It's cheaper to let the customers burn.” Week 11 Lecture B ENG 1P03 2011 12 Role of Engineers in the Ford Pinto Design and Production • Engineers involved throughout, but in particular: – Crash testing – Decision making with respect to design adjustments to reduce negative outcome of rear-end collision – Whistle-blowing Week 11 Lecture B ENG 1P03 2011 13 Questions 1. Did Ford do anything wrong? 2. Did Ford’s engineer’s do anything wrong? 3. What reason do you have to believe that the Pinto was less safe than its competitors? 4. Was Ford just a victim of bad publicity? Week 11 Lecture B ENG 1P03 2011 14 Safety in Design • Safety – “ The condition of being safe from undergoing or causing hurt, injury, or loss.” • Risk – “ The possibility of loss or injury.” • No such thing as absolutely safe. • Acceptable Risk – A level of risk at which the benefits are judged to outweigh potential loss or injury. Week 11 Lecture B ENG 1P03 2011 15 Constant Risk p probability c cost r risk pc=r log(p) + log(c) = log(r) Event probability p High Risk Low Risk r = 100 r = 10-2 c Event cost ($) Week 11 Lecture B ENG 1P03 2011 16 i>clicker Question Event probability Which of the following statement is true? A. C is riskier than A p B. C is more costly than D C. D is more likely B B D. B is riskier than D E. None of the above C A D c Event cost ($) Week 11 Lecture B ENG 1P03 2011 17 Ford Pinto Discussion • Any questions about the Ford Pinto and its story? • What really bothered you about the discussion? • What is your opinion on how the engineers and company acted? • How was safety evaluated? • Why did Ford get sued if they didn’t break any laws and acted competently? • How did engineers miss such an obvious interaction between the bolts on the differential and the fuel tank? Week 11 Lecture B ENG 1P03 2011 18 Ford Pinto Discussion • How does the public ascertain safety? • Was the Pinto more or less safe than its competitors? • Was the Pinto safe enough? • What are mechanisms in place to ascertain safety? – The Profession – Governments – The markets • What should have happened? Week 11 Lecture B ENG 1P03 2011 19 Brake System Scenario • Design decision: decide between two passenger car brake systems: A. Lower cost; less safe B. Higher cost; more safe • Safety measured by stopping distance • Stopping distance correlates strongly with severity of accident and injury • Under what conditions is it ethical to recommend the lower cost system? • Can safety be evaluate only by technical measures? • Safety factor Week 11 Lecture B ENG 1P03 2011 20 The Maximalist Approach to Safety • Minimalist approach – Safety responsibilities – Guidelines and principles for recognizing and controlling hazards – Applicable safety codes and standards • Maximalist approach – How do you make a safer car? – How do you lead with ethics/values rather than be constrained by them? Week 11 Lecture B ENG 1P03 2011 21 Volvo’s Safety Concept Car (SCC) Week 11 Lecture B ENG 1P03 2011 22 Week 11 Lecture B ENG 1P03 2011 23 Week 11 Lecture B ENG 1P03 2011 24 SCC Design Features • See-through A-pillars • “Invisible” B-pillars • Active rear-view mirrors • Rearward-facing cameras • Adaptive headlights • Night vision Week 11 Lecture B • Collision warning sensors • Lane centring • Flashing brake lights • Four-point safety belts ENG 1P03 2011 25 Week 11 Lecture B ENG 1P03 2011 26 ABS • A major safety advance for automobiles • First entered public consciousness through advertising in the late 1980’s and 1990’s • Daimler-Benz took credit for move of the development • “Daimler claimed that the invention was driven so clearly by its interest in public safety that the corporation would not pursue any patent infringement suits over its competitors’ systems.” Week 11 Lecture B ENG 1P03 2011 27 ABS • Advertising suggested this was engineering design based on corporate vision. • The opposite is closer to the truth. It took over 25 years of the work of a community of engineers and many dead-ends before the vision turned into an affordable, mass-producible result. Week 11 Lecture B ENG 1P03 2011 28 ABS • It is an example of good design: – It’s function is easy to understand. – It is socially desirable. – It works. • “The problem at hand and the community addressing it were defined and evolved simultaneously.” Week 11 Lecture B ENG 1P03 2011 29 ABS • Initially a community of 50 researchers and design engineers formed around the problem of skidding automobiles. They met in 1958. • There was no solution. • They proposed many alternatives such as brake distribution, disc brake systems, self-energizing systems, hydraulic systems, etc. • The British Road Research Laboratory (RRL) had discovered that skidding caused a significant number of accidents: about 27% of all accidents on roads in 1957. Week 11 Lecture B ENG 1P03 2011 30 ABS • Lister adapted the first device from an aircraft. Results were disappointing. The distance the car took to stop was much longer. Braking efficiency was too low. • Dunlop developed another attempt device that was prohibitively expensive and didn’t reduce the stopping distance. • A third device was design using an electronic control module that could detect of calculate the angular deceleration. Week 11 Lecture B ENG 1P03 2011 31 ABS • Teldix changed the problem from reacting to wheel lock-up to regulating the braking. The idea was to detect and regular imminent skidding. • They added another criterion: it had to reduce stopping distance on both wet and dry pavement. • Siemens and American Microsystems jointed the community by contributing paper at conferences on the use of purpose-design, solid state microprocessors in cars. Week 11 Lecture B ENG 1P03 2011 32 ABS • Most ABS in the 60’s and 70’s were developed in partnership between a brake producer and automobile manufacturer: – – – – Kelsey-Hayes & Chrysler Alfred Teves with BMW Benedix-DBS with Citroën Teldex with Daimler-Benz • By the end of 80’s manufacturers were solid on the idea Week 11 Lecture B ENG 1P03 2011 33 ABS • A June 1999 National Highway Traffic Safety Administration (NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 22%. • A 2003 Australian study[1] by Monash University Accident Research Centre found that ABS: – Reduced the risk of multiple vehicle crashes by 18% – Reduced the risk of run-off-road crashes by 35% Week 11 Lecture B ENG 1P03 2011 34 Week 11 Lecture B ENG 1P03 2011 35 Week 11 Lecture B ENG 1P03 2011 36 ABS Effectiveness ABS improves steering control during rapid deceleration especially on slippery road surfaces. ABS shortens the stopping distance, if braking efficiency is high enough, because on most surfaces static friction is greater than kinematic friction. Week 11 Lecture B ENG 1P03 2011 37 Munich Taxicab ABS Study • Munich taxi fleet • Taxis were all same make and identical in all other respects • Majority of drivers randomly assigned and remaining drivers rotated • 747 accidents – ABS cars under-represented in accidents in which the car driver was culpable – ABS cars over-represented in accidents in which the cab driver was not at fault – Accident severity was independent of presence of ABS Week 11 Lecture B ENG 1P03 2011 38 Munich Taxicab ABS Study 2 • Accelerators used to measure acceleration and deceleration at 100 Hz for a total 3276 hours of driving • Extreme deceleration occurred more often in cars with ABS Week 11 Lecture B ENG 1P03 2011 39 Munich Taxicab ABS Study 3 • Observers recorded driving style. • Drivers of cabs with ABS made sharper turns in curves, were less accurate in their laneholding behaviour, proceeded at a shorter forward sight distance, made more poorly adjusted merging manoeuvres and created more “traffic conflicts” • Compared with non-ABS cabs, ABS cabs were driven faster Week 11 Lecture B ENG 1P03 2011 40 Munich Taxicab ABS Study 4 • Analysis of accidents for the year following the initial study saw no difference in accident or severity rate but ABS taxis had more accidents under slippery driving conditions Week 11 Lecture B ENG 1P03 2011 41 Munich Taxicab ABS Study Conclusions: 1. Drivers utilized ABS to their advantage, but no improvement in the accident loss per time unit of exposure to traffic could be seen. 2. A reduction in the accident rate did occur when the drivers’ target level of risk was reduced by increasing their expected cost of risk behaviour. Did ABS merely shift the risk instead of reducing it? Week 11 Lecture B ENG 1P03 2011 42 Risk Homeostasis Theory In risk homeostasis theory, the hypothesis called risk homeostasis suggests that individuals have a set level of acceptable risk. Reducing risk in one area will therefore lead to a change in behaviour that increases risk elsewhere so that the individual’s level of acceptable risk remains constant. Week 11 Lecture B ENG 1P03 2011 43 Review • Holding the welfare of the public paramount is a solemn duty. • Evaluating what is safe enough and making something safe are two different things. • Acceptable risk is key to the understanding of safety. • Importance of communicating risk. Week 11 Lecture B ENG 1P03 2011 44 ...
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This note was uploaded on 12/11/2011 for the course ENG 1c03 taught by Professor Lee during the Spring '11 term at Adventista de las Antillas.

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