Accidents, Safety, & Risk

Question 1

Heinrich’s accident triangle

Answer 1

-Heinrich worked for traveler’s insurance company, analyzed over 550k workplace accidents-observed constant ratio between fatal/major injury, minor injury, and near-miss!-1:29:300-promoted behavioral-based safety (behavior and culture!)-triangle later echoed in alberta injury control research in hospital admissions to emerg!

Question 2

“Normal Accidents”

Answer 2

-highly developed technological systems very complex-failure of one component interacts with another-accidents normal, to be expected

Question 3

Why did British Medical Journal ban use of word “accident”?

Answer 3

-most injuries predictable and preventable, whereas true accidents unpredictable and therefore unavoidable!-however, “accident” still used in ICD-10, external causes of morbidity and mortality

Question 4

Wogalter, 4 steps to increase safety

Answer 4

1) remove hazard 2) guard against hazard 3) have proper training 4) post warnings

Question 5

Wogalter, critical elements of warnings

Answer 5

1) signal word (“DANGER”), word that gets your attention2) description of Hazard (“shallow water”)3) description of consequences (“you can hit your head and die”)4) instructions (“no diving”)ALL FOUR!!!

Question 6

Wogalter, factors influencing effectiveness of warnings

Answer 6

Warning information (sign!)>Attention (will you notice it?)>Comprehension (understand it?)>Beliefs/Attitudes>Motivation (willing to jump over guard rails for best picture???)>Compliance behaviore.g. drinking and driving seen as a threat to personal safety by 97%, but 21% do it (Gallup, 1999)

Question 7

Why people disregard safety instructions? Lo probability risks? Zeitlin

Answer 7

Breakdown in:1. Communication: user avoids hazard if properly informed2. Decision-Making: user aware of safeguards, but chooses to ignore them-people willing to take (perceived) low-probability risks)-people accept more risk if they have actual (or perceived) control over the situation (lottery tickets…)-cost/benefit tradeoff-experience (feel like immune with experience)

Question 8

describe the risk-taking personality (zuckerman)

Answer 8

• “Sensation-seeking” personality type - risk-taking behaviours include:• varied sexual experience• greater use/variety illicit drugs • risky drivers• risky sports, risky play

Question 9

chainsaw instruction recognition/compliance study, zuckerman: methods

Answer 9

methods:-2 groups, experienced chainsaw users, novices (never used in life)-half received lecture on aerospace equipment design, half on how safe operating procedures improve industrial safety-all subjects given 10 safety instructions-given recognition test on safety instructions (is this a safety instruction, or not?)-performed task with actual chainsawresults:-type of lecture had no significant effect-BOTH experienced & novices remembered 9/10 instructions (recognition)-41% experienced complied w/ actual instructions, 70% of novices!conclusions-users UNDERSTOOD instructions-but experience influenced decision to follow, decreased compliance-following instructions seen as unnecessary-how improve safety-compliant behavior? (those who use the most, least likely to follow safety instructions!)

Question 10

chainsaw instruction recognition/compliance study, zuckerman: results

Answer 10

results:-type of lecture had no significant effect-BOTH experienced & novices remembered 9/10 instructions (recognition)-41% experienced complied w/ actual instructions, 70% of novices!

Question 11

chainsaw instruction recognition/compliance study, zuckerman: conclusion

Answer 11

conclusions-users UNDERSTOOD instructions-but experience influenced decision to follow, decreased compliance-following instructions seen as unnecessary-how improve safety-compliant behavior? (those who use the most, least likely to follow safety instructions!)

Question 12

risk analysis

Answer 12

“estimation of consequences associated with particular errors - includes estimate of probability”-risk = p (error) × consequences (error)-can be any sort of risk (loss of life, money)-insurance companies (what are risk of this client?)-used for many decision types.estimates of safety.estimates of probable success.types of training to use to help operators not to miss important errors

Question 13

Peltzman effect (1975)

Answer 13

• hypothesized tendency for people to react to a driving safety regulation by increasingother risky behaviour, offsetting some or all of the benefit of the regulation- safety devices in automobiles have saved occupants’ lives, but at the expense of morepedestrian deaths and more nonfatal collisions- this is a form of “behavioural adaption” or “risk compensation”

Question 14

Risk homeostasis theory, definition (gerald wilde)

Answer 14

• degree of risk-taking behaviour (and magnitude of loss due to accidents and lifestyle-dependent disease) are maintained over time–unless TARGET RISK (define) level changes-we all try to have a consistent level of risk in our lives: different from person to person, but constant within

Question 15

Target risk (gerald wilde)

Answer 15

• target risk: level of risk a person accepts to maximize overall expected benefit froman activity- determined by 4 categories of subjective utility (“motivating”) factors:1+2. expected benefits/costs of comparatively risky behaviour 3+4. expected benefits/costs of comparatively safety behaviour - greater risk as #1 and #4 increase; and/or as #2 and #3 decreaseFor speeding vs. driving slowly, what are some examples of each of the 4 factors?

Question 16

Risk Homeostasis Theory evidence

Answer 16

• the introduction of “child-proof” medicine bottles in 1972 resulted in poisonings in (if it was dangerous, mommy would have put it on top shelf!)children under age 5 increasing by 3,500 per year• laws banning cell phone use while driving have not reduced crashes• people drive closer to bicyclists who are wearing helmets• motorcyclists drive faster when wearing full leathers, compared to wearing onlyunderpants• stricter NASCAR regulations have led to an increase in crashes• hockey players got more penalty time after switching to helmets with visors• when Sweden switched from driving on the left side of the road to driving on the right side, traffic fatalities decreased by 17% in the next 12 months (but after 2 years, fatalities increased to their original levels)

Question 17

Adams, risk compensation in seat belt use

Answer 17

-seat belts reduce chances of death by 41%, but does legislation reduce risk too?-laws passed over 80 jurisdictions worldwide-only measurable change in UK.use rose from 40-90%, fatalities decreased 20%.BUT confounding factor, firm campaign against drunk driving introduced same time.deaths of front seat belt-wearers decreased by 200.BUT, pedestrian, cyclist, rear-seat passenger deaths INCREASED by 800!-increase in risky behavior to compensate for safety of seat belts?

Question 18

Munich Taxicab Experiment

Answer 18

-part of taxi cab fleet installed ABS systems (retrofitted, rather than just buying new cars! costly!!!!)-ABS: prevents wheel lock up under extreme braking conditions (show worth on slippery)part I-drivers rotated cars-MORE collisions in ABS cars!part II-researchers installed accelerometers (didn’t tell drivers)-more rapid deceleration in ABS cars!part III-observers hailed cabs as if passengers, recorded driving style-double-blind, driver didn’t know if being observed, observer didn’t know if ABS or not-ABS drivers.sharper turns.less accurate lane-holding-tailgated-more traffic conflicts (swift actions required by traffic participant to avoid collision)-ABS cabs driven faster!-collisions dropped years later.. why? cab company made drivers pay for part of repairs!!! (increased expected cost of risky behavior)

Question 19

criticisms of Risk Homeostasis Theory

Answer 19

-not falsifiable (no way to measure people’s estimations of 4 stages risk)-no rl b/t helmet use and risky motorcycle riding-speed limit laws decreased fatalities per unit of time driving

Question 20

is ABS safer?

Answer 20

overall, yes-reduction on wet road crashes, pedestrian crashes, and rear-endersBUT-30% increase being rear-ended (2% net gain!)-drive in weather conditions previously avoided-drive faster-follow closer-increased rollover risk-similar data on effectiveness of brakes when introduced in 1938!!

Question 21

how reduce accidents? (sanders & mcCormick, 1993)

Answer 21

-procedural checklists-warnings-training.stress learning of safe behaviors.ensure learned behaviors actually TRANSFER to task.evaluate effectiveness-feedback & reinforcement-role models-incentive programs-increase perception of risk (s. african gold-mining acidents, mostly due to failure to perceive hazard, or underestimating one!)

Question 22

shared space rationale, unintended consequences

Answer 22

-traditional approach to triple-E traffic calming: engineering, enforcement, education (e.g. speed bumps, photo radar, public service announcements)-traffic engineers try segregating vehicle traffic from pedestrian/bicycle (but, impossible, the must eventually cross paths like crosswalks)-increasing traffic usually means more roadways for more traffic-regulations indicated by traffic signs (70% ignored by drivers!)unintended consequences-moving people off streets makes them LESS safe when they do inevitably have to CROSS the street-human scale of urban environment obliterated, not walkable, not human focused

Question 23

what are shared spaces?

Answer 23

aka complete streets-integration of vehicle and pedestrian traffic-intersections: NO traffic control devices (e.g. signals, signs, road markings, pedestrian crossings)-architecture of road determines traffic flow-resulting ambiguity FORCES drivers to be more cautious and pay more attention, “unsafe is safer” -RESULTS: been adopted in Europe and USA, causing decrease in collisions, casualties, and increased liveability!

Question 24

counter-intuitive advantages of roundabouts/traffic circles, and lower speed limits

Answer 24

-speed up traffic (on average) b/c no stopping for red lights-vehicles when moving, travel more slowly-risk of t-bone collisions virtually eliminated-roads w/ 55mph limit can handle MORE traffic than 70mph.b/c have to leave more space the faster you go, so roads are used less efficiently (more cars, burning less fuel!)

Question 25

practical lessons from shared space

Answer 25

1. road tells story: road and surroundings indicate which behavior appropriate & required2. make room for people: encourage interaction and facilitate eye contact!3. users have a say: incorporate citizen input and cooperate w/ government4. details can make/break design: choose materials that suit building and landscape (right, won’t be liveable and used if no benches and green space…)5. better chaotic than pseudo-safe: do not try to remove that UNSAFE feeling, but USE it to best effect

Question 26

shared spaces pros and cons

Answer 26

CHECK better traffic flow: shorter travel times, less pollutionCHECK reduced collisionsCHECK aesthetics: less visual clutter from signs, traffic lightsCHECK less nannying: less interference from rules/regulations, drivers make own decisions[X] vital signs not available (some drivers may find it jarring not used to it)[X] lack of railings, curbs, barriers, hazardous for BLIND pedestrians.esp. b/c assistance dogs trained to stop at curbs![X] design encourages some drivers to bully unsure/anxious cyclists/pedestrians[X] effects due to novelty, over time, drivers be less careful