Lecture 26: Human Behavior and Road Safety

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Highway Traffic and Safety Analyses
Lecture 26 Human Behavior and Road Safety
Purdue University School of Civil
Engineering West Lafayette
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Human Behavior

• 85-95 percent of crashes are attributed by
  experts to faulty human behavior

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Human Behavior

• Theories
• Perceived vs. accepted risks
• Theory of rational choice
• Homeostasis theory
• Behavioral issues
• Aggressive driving
• Runs on red
• Speeding
• Road rage
• Countermeasures

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Theories
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Perceived vs. Accepted Risks

• Perceived risk
• Traffic and road situation
• Driver traits
• Driver experience (knowledge)
• Driver state
• Accepted risk
• Driver state and traits
• Travel purpose and time constraints
• Perceived gain from taking a risk

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Perceived and Accepted Risksversus Objective Risk
Road
Traffic
Driver
Objective Risk
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Perceived and Accepted Risksversus Objective Risk
Road
Driver Behavior
Traffic
Driver
Objective Risk
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Perceived and Accepted Risksversus Objective Risk
Perceived Risk
Road
Driver Behavior
Accepted Risk
Traffic
Driver
Objective Risk
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Perceived and Accepted Risksversus Objective Risk
Sweden changed to driving on the right. It
resulted in 17 less road deaths in the first
year (Guardian, 26 January 1996). Accepted risk
? , perceived risk ? gt Risk-taking behavior
? After introducing free-market economy in Poland
in late 1980s, the crash rates increased by 30
percent. Accepted risk ?, perceived risk ?
gt Risk-taking behavior ?
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Theory of Rational Choice

• Drivers consider
• Alternative behaviors (slow down, accelerate,
  change lane, etc.)
• costs associated with each behavior (likelihood
  of crash and its outcome)
• benefits associated with each behavior (time
  gain, personal satisfaction)
• Drivers select the alternative with the highest
  net benefit

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Risk Homeostasis

• Drivers have their own target risk
• They reduce (compensate) risk with more cautious
  behavior if
• Perceived Risk gt Target Risk
• They change behavior towards more dangerous if
• Perceived Risk lt Target Risk

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Risk Homeostasis

• Examples of risk-taking behavior
• Risky leisure activities (mountain climbing,
  rodeo riding, gambling, etc.)
• The first indicator
• In 1968, Congress mandated seat belts and several
  other safety equipment
• 20-percent reduction in fatalities were predicted
  as a result of improving millions of cars
• Safety researches found no difference in
  fatalities

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Risk Homeostasis

• Seat belts
• Volunteers drove go-karts with and without seat
  belts
• The average speed of people wearing seat belts
  was higher than those who did not
• Speed limit
• In 1987, the federal government allowed for
  raising speed limit from 55 to 65 miles/hour
• Fatalities in states with the 65 speed limit
  where lower than in the other states by three
  percent
• WATCH Do Safer Cars Dangerous Drivers?

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Behavioral Issues
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Aggressive Driving What behavior is aggressive?
survey of Canadian drivershttp//www.thenewstee
l.org/news/documents/show_arc_press.cfm?press_id3
40
Percent of Respondents
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Aggressive Driving Red Signal Running

• In 1998, there were 89,000 red light running
  crashes that resulted in 80,000 injuries and 986
  deaths.
• 56 percent of Americans admit to running red
  lights.

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Aggressive Driving Red Signal Running

• Indiana drivers survey (2000/2001)
• 56 see red signal running several times a week
• 55 think that drivers are in hurry
• 27 think that drivers do not pay attention
• 68 think that less than 10 violators are
  ticketed by the police
• 59 believe in enforcement
• 78 would support photo-enforcement

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Aggressive Driving Red Signal Running

• West Lafayette research (2001/2002)
• No enforcement 20 of drivers arriving at the
  beginning of red signal runs it
• Residual effect of police enforcement 5 of
  drivers arriving at the beginning of red signal
  runs it
• The residual effect does not last long
• Violation rate significantly lower if students
  arent in the flow (vacation)

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Aggressive Driving Speeding
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Aggressive DrivingSpeeding
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Road Rage

• More congestion
• Cultural norms of disrespect
• Road Rage

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Road Rage

• Verbal
• yelling, honking, rude gestures, insulting
• Quiet
• rushing, competing, resisting
• Epic
• cutting in, blocking, chasing, fighting, shooting

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Countermeasures
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CountermeasuresPerceived vs. Accepted Risks

• Increase the risk perception
• Educate about human limitations
• Provide road hazard facts to public
• Educate about drug impacts
• Display warning signs
• Law and enforcement (additional risk)
• Decrease the risk acceptance
• Gratification of safe driving (premium by
  employer)
• Any other ideas?

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CountermeasuresAggressive Driving AAA Survey
of Agencieshttp//www.aaafts.org/Text/research/Ro
adRageFinal.htm
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CountermeasuresRed Signal Runninghttp//safety.f
hwa.dot.gov/community/srlr_ongoing.htm

• Photo-enforcement
• 1997, Oxnard, California, population 151,000
• Nine camera sites, 104 fine and one point on
  the driver's license.
• A 30-day warning period during which red light
  cameras photographed violators, but no tickets
  were issued.
• The red light violation rate reduced 42 percent.
• Increase of red signal compliance on unequipped
  intersections as well

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CountermeasuresSpeeding Survey of
Drivershttp//www.nhtsa.dot.gov/people/injury/agg
ressive/unsafe/counter/Chapt1.html

• More police assigned to traffic (85)
• More frequent ticketing (82)
• Double or triple fines (81)
• Revoking licenses more often (81)
• Increased insurance costs (80)
• Road design changes (78)

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CountermeasuresRoad Ragewebpages.marshall.edu/h
arrison2

• Database of Unsafe Driving license plate
  numbers of drivers who were acting upon road rage
• Quality Driving Circles groups of drivers who
  meet discuss their difficult driving experience
• Education - educational materials, public service
  announcements, self-tests, self-help and
  self-education through the Internet

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CountermeasuresRoad Ragehttp//www.aaafts.org/Te
xt/research/RoadRageFinal.htm

• Legislation directed at controlling road rage in
  17 states
• Enforcement unmarked cars, plain-clothes police
  officers, helicopters, airplanes, video cameras,
  air patrols in contact with grounded policemen
  (TRIAD Targeting Reckless, Intimidating, and
  Aggressive Driving in Ohio)

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CountermeasuresImprove the Roadwww.nous.org.uk/r
eform.html

• "Don't attempt to reform man. An adequately
  organized environment will permit humanity's
  original, innate capabilities to become
  successful. Politics and conventionalized
  education have sought erroneously to mould or
  reform humanity.
• Utopia or Oblivion, Buckminster Fuller, 1969.
• "increasing safety and decreasing accidents by
  engineering improvements of motor vehicles while
  also providing overpasses and banked turns for
  the vehicles to drive on, instead of trying to
  reform the vehicle-drivers' behaviors" .
• Critical Path, Buckminster Fuller, 1981.