Human Factors in Traffic Safety Fall 2019 Important Resources Evans, L. (2004) Traffic Safety. Science Serving Society. Bloomfield Hills, MI (see also Evans, L. (1991) Traffic Safety and the Driver. Van Nostrand Reinhold. New York, N.Y.) Dewar, R.E., and P.L. Olson. (2007) Human Factors in Traffic Safety. 2nd edition, Lawyers & Judges Publishing Company, Inc., Tucson, AZ.
Shinar, D. (2008) Traffic Safety and Human Behavior. Emerald Group Publishing Limited, Bingley, UK. Human-Environment-Vehicle System Provide a conceptual framework to analyze motor vehicle collisions. Example: A 20-year old man with little driving experience, is taking an unfamiliar road on his way to an interview. His vehicle is not properly maintained. In fact, the tires are in poor shape. At some point on the trip, the
rain starts to fall. Shortly thereafter he enters a horizontal curve with a radius below minimum standards, loses control of the vehicle and run off the road into a tree located within a few feet of the traveled way. Question: What are the contributing factors that have lead to this crash? Human-Environment-Vehicle System System Component
Event Circumstance Human Trip Young, inexperienced, stressed Vehicle
Choice of vehicle Tires in poor condition Environment Rain Wet and slippery surface Environment
Curve Below standard Human Steering maneuver Oversteering Human
Loss of control Unstabilized shoulder Environment Roadside conditions Tree too close traveled way Outcome
Impact (crash) Crash Contributing Factors Human Factors (93%) Road Environment (34%) 57% 27%
3% 1% 6% 3% 2% Vehicle (12%) http://cyberlaw.stanford.edu/blog/2013/12/human-error-cause-vehicle-crashes
https://www.fhwa.dot.gov/publications/publicroads/95winter/p95wi14.cfm Haddon Matrix Agent Host Physical Environme nt Social
Environme nt Pre-event During the event Post-event William H. Haddon, Jr., came up with a Matrix to systematically analyze car crashes in a 1972 paper.
Using the Haddon Matrix (based on Cassens 1992) Agent e.g. car Host e.g. driver Physical Environme
nt Social Environme nt Before the event (crash) Good Good
brakes, car vision, properly alert maintained Welldesigned roads and highways Penalize drunk driving
heavily During the event Airbags, anti-lock brakes Motorcycle helmet, seatbelt
Non-rigid roadside poles, crash barriers Mandate the use of safety glass in windows
After the event Burnresistant fabrics in car cabin Emergency Effective medical emergency care
transport system Support medical and rehabilitati Risky Behavior and Road Accident Control System Elements: The Road
User Myth: accident prone individuals Safe and successful operation is influenced by factors: physical, psychological and cognitive. Spare mental capacity Human errors: rule based, knowledge base, and skill based Drivers capable of adapting to driving situations: strategic, tactical and operational
System Elements: The Vehicle Design of the vehicle: seats, easy ingress and egress, essential controls within reach Vehicle is dynamic device (must be in accordance to driver expectancy) Uniformity in operation of controls and displays (not always uniform from one vehicle to the next)
System Elements: The Road Uniformity for highway design and traffic control devices Provide proper navigational information System still not fully adequate Research still on-going for understanding the relationship between road design (geometric, control devices, etc.) and safety. Perception and
Information Processing Perception Stimulus applied to any sense organs For motor vehicles: visual is the most important (also smell, auditory, tactile) Some important elements for driving task: color, contrast sensitivity, eye movement depth perception, static visual acuity, etc.
Fields of View Peripheral vision 60o Visual Cone Eye 10o Detection
Perception of Speed Important for: Passing vehicles on rural highways Turning in front of oncoming vehicles Accepting gaps Vehicle control and path finding (on curves) Vehicle operation during an emergency Decision making Perception of Speed
Road Characteristics Plays an important part in speed estimation Vehicle size Perception highly influenced by vehicle size
Speed adaptation Underestimating actual speed after slowing down from a typical highway speed (freeway exists) Motion sensitivity Perception taken from the forces acting on the vehicle Judgment of Spacing
Driver Perception and Response Time Stages of Perception-Response Time Detection Identification Decision Response Deduced Perception-Response
Time Perception-Response Time by Geometric Design Elements Factors Affecting PRT Detection Object conspicuity Amount of information being processed by the driver
Identification Poor visibility: nighttime and fog Speed and trajectory of the potential hazard Factors Affecting PRT Decision Choice: steering, braking (& accelerating?)
Choice may sometimes be more complex Response Usually minor component of PRT Time allocated for foot leaving the accelerator and hitting the brake pedal Factors Affecting PRT
Driver Expectancy Predisposition on the part of drivers that something will happen or be configured in a certain way Violation of expectancy will lead to longer PRT Night versus Day Many situations have the same PRT (see next figure) Detection may play a role in the difference
Night versus Day PRT Factors Affecting PRT Driver Fatigue Difficult to measure, but increase in driver fatigue will increase PRT
Age and Gender PRT increases with age (0.44 sec for 20 years to 0.52 for 70 years of age) Female drivers have longer PRT than male drivers Looking Behavior Changing Lanes at Intersections Location of Eye Fixations Read all signs
Read only important signs Did not read any signs Eye Fixation for Car Radios Eye Fixation for Car Mirrors
Eye Fixation by Daylight Conditions Driver Performance Acquisition of Driving Skills Cognitive Phase Associative Phase Autonomous
Phase Eye Fixations of Novice Drivers Individual Differences Personality Relationship between personality and crashes is weak (i.e., personality changes with time,
confounding variables) Some personality trait causing fatigue may lead to higher risk of crashes Emotions Emotional disturbances affect all aspect of our life, including driving Higher heart rate and blood pressure associated with increase traffic flow
Mental Disorder and Fatal Crashes Individual Differences Stress Stress can be caused by emotional (e.g., divorce), cognitive (e.g., cut-off), and physiological (e.g., sick). Leads to aggression, confusion and risky behavior
Motivation Car ownership important to people Motivational elements: travel for necessity, social status, freedom, self-expression Faulty motivation may lead to higher risk behavior Marketing of motor vehicles Individual Differences
Risk Taking Behavior Objective versus subjective risk Sensation seeking (SS) individuals: relationship not established SS and risky driving Risk homeostasis theory Social Factors Drivers are influenced by other drivers culture of driving Drivers are also influenced by passengers
(family members versus teenagers) Male and Female Drivers Male and Female Drivers Male and Female Drivers Differences by Age Group Driving Skills versus Crashes
Driving Skills versus Crashes
