Highway Traffic and Safety Analyses Lecture 26: Human Behavior and Road Safety Purdue University School of Civil Engineering West Lafayette
Human Behavior 85-95 percent of crashes are attributed by experts to faulty human behavior
Human Behavior • Theories • Perceived vs. accepted risks • Theory of rational choice • Homeostasis theory • Behavioral issues • Aggressive driving • Runs on red • Speeding • Road rage • Countermeasures
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
Perceived and Accepted Risksversus Objective Risk Road Traffic Driver Objective Risk
Perceived and Accepted Risksversus Objective Risk Road Driver Behavior Traffic Driver Objective Risk
Perceived and Accepted Risksversus Objective Risk Perceived Risk Road Driver Behavior Accepted Risk Traffic Driver Objective Risk
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 => Risk-taking behavior After introducing free-market economy in Poland in late 1980s, the crash rates increased by 30 percent. Accepted risk , perceived risk => Risk-taking behavior
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
Risk Homeostasis • Drivers have their own target risk • They reduce (compensate) risk with more cautious behavior if Perceived Risk > Target Risk • They change behavior towards more dangerous if Perceived Risk < Target Risk
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
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?
Behavior 1999 2000 Tailgating 93 93 Passing on the shoulder 88 87 Making rude gestures 86 87 Pulling into someone else's parking space 80 82 Changing lanes without signaling 75 73 Flashing high beams at car in front 74 72 Drive through yellow lights turning red 69 69 Merge at last second with traffic on highway 73 66 Speeding (20km/h or more over speed limit) 65 65 Aggressive Driving What behavior is aggressive? – survey of Canadian drivershttp://www.thenewsteel.org/news/documents/show_arc_press.cfm?press_id=340 Percent of Respondents
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.
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
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 aren’t in the flow (vacation)
Road Rage More congestion + Cultural norms of disrespect = Road Rage
Road Rage • Verbal • yelling, honking, rude gestures, insulting • Quiet • rushing, competing, resisting • Epic • cutting in, blocking, chasing, fighting, shooting
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?
CountermeasuresAggressive Driving – AAA Survey of Agencieshttp://www.aaafts.org/Text/research/RoadRageFinal.htm
CountermeasuresRed Signal Runninghttp://safety.fhwa.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
CountermeasuresSpeeding –Survey of Drivershttp://www.nhtsa.dot.gov/people/injury/aggressive/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%)
CountermeasuresRoad Ragewebpages.marshall.edu/~harrison2 • 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
CountermeasuresRoad Ragehttp://www.aaafts.org/Text/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)
CountermeasuresImprove the Roadwww.nous.org.uk/reform.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.