Human Factors in Traffic Safety

Robert E. Dewar and Paul L. Olson

Contributors: Gerson J. Alexander, Jeff K. Caird, Paul Green, Lyn Haber, Ralph Norman Haber, Peter A. Hancock, Fred R. Hanscom, C. Alan Hopewell, Michael S. Janoff, Herbert Moskowitz, Alison Smiley

Preface

Chapter 1: Introduction
Paul L. Olson and Robert E. Dewar
1.1 Human Factors
1.2 The Driving Task
1.3 System Elements
A. The road user
B. The vehicle
C. The road
1.4 The Investigation of Motor Vehicle Accidents
References

Part One: The Driver

Chapter 2: Perception and Information Processing
Robert E. Dewar, Paul L. Olson and Gerson J. Alexander
2.1 Introduction
2.2 Perception
A. Background
B. The eye
C. Photometric terms
D. Contrast
2.3 Perception of the Road
A. Driver's awareness
B. Hazard detection and recognition
C. The effects of adverse weather
2.4 Visual Search
A. Driver's field of view
B. Useful field of view
2.5 The Perception of Speed
A. The role of speed in driving
B. How speed information is used
C. Speed perception and road characteristics
D. Speed perception and vehicle size
E. Speed adaptation
F. Motion sensitivity
2.6 Car Following
2.7 Auditory Information
2.8 Information Processing and Accidents
A. How it works
B. Information processing and accidents
2.9 Driver Attention and Workload
2.10 Steering
2.11 Positive Guidance
A. The basic concept
B. Task complexity
C. Principles of information placement
D. Expectancy
2.12 Summary
References

Chapter 3: Driver Perception-Response Time
Paul L. Olson
3.1 Introduction
3.2 Background
A. Definition
B. Stages of perception-response time
1. Detection
2. Identification
3. Decision
4. Response
3.3 Human Perception-Response Time
A. Background
B. Driver perception-response time
3.4 Decision Sight Distance
3.5 Overview of Research
3.6 Factors Affecting Perception-Response Time
A. Detection
B. Identification
C. Decision
D. Response
E. Driver expectancy
F. Night versus day
G. Chemicals and driver fatigue
H. Age and sex
3.7 Situations That Do Not Fit the Perception-Response Model
A. No clearly defined entry
B. Erroneous assumption or identification
3.8 Overview
References

Chapter 4: Where Do Drivers Look While Driving (and for How Long)?
Paul Green
4.1 How Is Glance Behavior Described?
A. What are the terms used to describe glance behavior?
B. What are some general characteristics of driver glance behavior?
C. How is glance behavior measured?
4.2 Why Are Eye Fixations of Interest?
A. Does visual demand actually relate to crashes?
B. Does looking at an object guarantee the object is noticed?
4.3 What Is Typical Looking Behavior?
4.4 How Is Glance Behavior Affected by the Road Environment?
A. Where do drivers look when driving curves?
B. How do traffic and other external demands affect where drivers look?
C. How have eye fixation data been used to assess the merits of road and 
vehicle markings, and signs?
4.5 How Does Glance Behavior Change with Driver Characteristics?
A. How does glance behavior change with driving experience?
B. What is the effect of fatigue on glance behavior?
C. How do alcohol and other drugs affect eye movements?
4.6 What Is the Effect of Vehicle Characteristics on Glance Behavior?
A. How do eye glance patterns vary as a function of the vehicle driven?
B. How does scene illumination alter glance characteristics?
4.7 How Might In-Vehicle Devices Affect Driving?
A. What is typical looking behavior for in-vehicle devices?
B. How long can drivers look to the vehicle interior?
4.8 Conclusions
4.9 A Final Thought
References

Chapter 5: Individual Differences
Robert E. Dewar
5.1 Introduction
5.2 Personality
5.3 Emotions
5.4 Stress
5.5 Aggressive Driving
5.6 Motivation
5.7 Self-Assessment of Driving Skills
5.8 Risk Taking
5.9 Behavioral Compensation
5.10 Social Factors
5.11 Driver Attitudes
5.12 Differences between the Sexes
5.13 Driving Experience
5.14 Physical Factors and Motor Skills
A. The role of motor control in driving
B. Age-related deficits
C. Physical disabilities
5.15 Conclusions
References

Chapter 6: Fatigue and Driving
Alison Smiley
6.1 Introduction
A. Definitions of fatigue
B. Measurement of fatigue
1. Subjective rating scales
2. Physiological measures
3. Performance measures
C. Causes of fatigue
D. The extent of the fatigue problem
E. Fatigue and accidents
6.2 Long Hours
A. Arousal and performance
B. Accident risk
C. Summary
6.3 Time of Day
A. Sleepiness
B. Performance
C. Accident risk
D. Summary
6.4 Inadequate Sleep
A. Performance
1. Shortened sleep
2. Shift work
3. Sleep apnea
B. Accident risk
C. Summary
6.5 Countermeasures to Sleepiness
A. Rest breaks
B. Food
C. Caffeine
D. Naps
E. ITS countermeasures
F. Education
G. Summary
6.6 Conclusion
Recommended Readings
References

Chapter 7: Alcohol and Drugs
Herbert Moskowitz
7.1 Introduction
7.2 Alcohol Use while Driving
7.3 Alcohol and Accidents
7.4 Single Vehicle Collisions
7.5 Subjective Measures of Impairment
7.6 Driving Abilities Impaired by Alcohol
7.7 Rate of Alcohol Consumption
7.8 Alcohol and Fatigue
7.9 Alcohol and Aggression
7.10 Alcohol and Degree of Injury
7.11 Drug Effects
References

Chapter 8: Age Differences†Drivers Old and Young
Robert E. Dewar
8.1 Older Drivers
A. Introduction
B. Demographics of older drivers
C. Difficulties experienced by older drivers
D. Older drivers in accidents
E. Increased vulnerability of the elderly
F. Sensory and perceptual changes
1. General considerations
2. Ocular changes
3. Accommodation
4. Visual fields
5. Eye movements and visual search
6. Sensitivity to light
7. Contrast sensitivity
8. Dark adaptation
9. Glare and glare recovery
10. Visual acuity
11. Dynamic visual acuity
12. Visual diseases
G. Attention
H. Psychomotor performance
I. Memory
J. Stress
8.2 Young Drivers
A. Introduction
B. Dangerous driving behaviors
C. Alcohol
D. Perception of dangerous situations
E. Self perception
F. Motivation and emotion
G. Differences between the sexes
H. Potential countermeasures
8.3 Conclusion
References

Chapter 9; Neuropsychological, Medical, and Psychiatric Disorders Affecting Motor Vehicle Operations
C. Alan Hopewell
9.1 Our Right to Drive and Our Right to Be Safe: Two Competing Interests
9.2 Regulatory and Legal Factors Relating to Disability and Automobile Driving
9.3 The Americans with Disabilities Act and Constitutional Analysis
9.4 Executive Dysfunction
9.5 Failure to Warn and the Special Relationship of Healthcare Providers
9.6 Risk Assessment, Risk Communication and Risk Management
9.7 The Prediction of Risk
9.8 The Communication of Risk
9.9 Narrative and Prescriptive Structure
9.10 Accident Risk Associated with Neuropsychological and General Medical Disorders
A. Our aging drivers and the dementias
B. Senile dementia of the Alzheimer type
C. Diffuse Lewy-body disease
D. Parkinson's disease (paralysis agitans)
E. Huntington's disease
F. Pick's disease (lobar atrophy)
G. Vascular and cardiac etiologies
H. Cardiac disorders
I. Traumatic brain injury
1. TBI survivors able to return to driving
2. Who can drive and what test batteries help assess risk?
3. Simple tests not sufficient
4. Dallas investigations
5. A high-risk cohort
J. Epilepsy
K. Spina bifida
L. Diabetes
M. Conclusions for diabetes
N. Dyssomnias
O. Psychiatric disorders and psychotropic medications
P. Schizophrenia and the psychotic disorders
Q. Attention deficit disorder
R. Psychotropic medications
9.11 Adaptive Driving Programs and Medical Decisions
A. Adaptive programs
B. Simulator training
9.12 Assessment Issues
A. The Cognitive Behavioral Driver's Inventory
B. The Neurocognitive Driving Test
C. The Drivers' Neuropsychological Rating Scale
D. Working with the family
E. The Four E's
9.13 Conclusions
9.14 Agencies of Interest
References

Part Two: The Vehicle

Chapter 10: Vehicle Design
Robert E. Dewar
10.1 Introduction
10.2 Requirements of the Driving Task
10.3 Anthropometry
10.4 Controls
10.5 Displays
10.6 Visibility from within the Vehicle
10.7 Visibility of Vehicles
A. Daytime running lights
B. Emergency vehicles
10.8 Trucks
10.9 Traffic Control Devices Relevant to Truck Operators
10.10 Agricultural Vehicles
10.11 Motorcycles
10.12 Vehicle Size and Safety
10.13 Older Drivers
10.14 In-Vehicle Electronic Devices
10.15 Cellular Phones
10.16 Driving Vehicles of the Future
10.17 Noise
10.18 Vibration
10.19 Safety Belts
10.20 Antilock Brake Systems
10.21 Conclusion

Chapter 11: Visibility with Motor Vehicle Headlamps
Paul L. Olson
11.1 Introduction
11.2 The Importance of Target Contrast
A. Definition
B. Calculating contrast
11.3 The Reflectivity of Objects in the Real World
11.4 Driver Vision at Night
A. Vehicle lighting systems
1. Technology used in automotive lighting
2. Characteristics of U.S. headlamps
3. The intensity-visibility distance relationship
4. Implications
B. The visibility provided by automotive headlamps
1. Research results
2. Target reflectivity
3. High beam versus low beam
4. Analytical approach
C. Correction for expectancy
11.5 Nighttime Driving Speeds
11.6 Overdriving of Headlamps
11.7 Chapter Overview
References

Part Three: The Roadway Environment

Chapter 12: Roadway Design
Robert E. Dewar
12.1 Introduction
12.2 Perception of the Road
12.3 Highway Hypnosis
12.4 Driver Workload and Roadway Design
12.5 Sight Distance
12.6 Roadway Width
12.7 Grades 
12.8 Intersections
12.9 Bridges
12.10 Roundabouts
12.11 Curves
12.12 Roadside Advertising
12.13 Safety Countermeasures
A. Traffic calming
B. One-way streets
C. Other engineering solutions
12.14 Road Design and Accident Litigation
12.15 Conclusion
References

Chapter 13: Traffic Control Devices
Robert E. Dewar and Paul L. Olson
13.1 Introduction
13.2 Criteria for Effective TCDs
A. Conspicuity
B. Legibility
C. Glance legibility
D. Comprehension
E. Response time
F. Other criteria
13.3 Problems with Traffic Control Devices
13.4 Signs
A. Classification of signs
B. The importance of signs
C. Symbol signs
D. Word signs
E. Changeable message signs
13.5 Signals
13.6 Pavement Markings
13.7 Rumble Strips and Speed Bumps
13.8 Post Delineators
13.9 Supplemental Warning Information
13.10 Environmental Factors
13.11 Aging and TCD Effectiveness
13.12 Methods for the Evaluation of TCDs
13.13 Cross-Cultural Comprehension of TCDs
13.14 Compliance with Traffic Control Devices
13.15 Conclusion
References

Chapter 14: Visibility under Roadway Lighting
Michael S. Janoff
14.1 Introduction
A. The purpose of roadway lighting
B. Sources of lighting
14.2 Definitions and Concepts
A. Basic lighting definitions
B. Lighting concepts
C. Visibility measures
14.3 Performance of Roadway Lighting
A. Background
B. Effects of roadway lighting on nighttime visibility
C. Effects of roadway lighting on nighttime safety
D. Effects of roadway lighting on nighttime traffic operations
E. Effects of roadway lighting on nighttime security and crime
F. Other effects of roadway lighting
14.4 History of Criteria and Standards for Roadway Lighting
A. History of roadway lighting standards
B. Other roadway lighting standards
C. Legal issues
14.5 Types of Roadway Lighting
A. Sources of roadway lighting
B. Roadway lighting geometry
C. Distribution of light
1. Overview
2. Beam distributions†design methods
D. Other factors
1. Light loss factors
2. Ownership and maintenance
14.6 Methods for Assessing Roadway Lighting
A. Introduction
B. Calculations and computer predictions
1. Hand calculations
2. Computer calculations
C. Measurement of roadway lighting
1. General measurement techniques
2. Illuminance measurements
3. Pavement luminance and veiling luminance measurements
4. Visibility measurements
D. Field evaluations of roadway lighting
1. Introduction
2. Still photography
3. Movie photography and video
14.7 Summary
References

Chapter 15: Environmental Factors
Robert E. Dewar and Paul L. Olson
15.1 Introduction
15.2 The Hours of Darkness
15.3 Twilight
15.4 Adverse Weather
15.5 Effects of Restricted Visibility
15.6 Driver Behavior in Fog
15.7 Conclusion

Part Four: Accident Causation and Remediation

Chapter 16: Railroad Grade Crossing Accidents
Robert E. Dewar
16.1 Introduction
16.2 The Accident Picture
16.3 Driver Behavior at Grade Crossings
16.4 Driver Perception of Crossing Hazards
16.5 Decision Errors
16.6 Attempting to "Beat the Train" across the Tracks
16.7 Traffic Control Devices
16.8 Pedestrian Safety
16.9 Countermeasures
16.10 Conclusion
References

Chapter 17: Highway Work Zones
Robert E. Dewar and Fred R. Hanscom
17.1 Human Factors and Work Zones
17.2 Accidents in Work Zones
A. Problems with accident data
B. The accident picture
17.3 Driver Information in Work Zones
17.4 Speed Selection and Control
17.5 Nighttime Conditions
17.6 Driver Behavior and Opinions
17.7 Older Drivers
17.8 Traffic Control Devices
17.9 Trucks
17.10 Lane and Shoulder Width
17.11 Safety Countermeasures
17.12 Conclusions
References

Chapter 18: Pedestrians and Bicyclists
Robert E. Dewar
18.1 Pedestrian Safety
18.2 The Pedestrian's Task
18.3 Pedestrian Accidents
18.4 Driver and Pedestrian Behavior
18.5 Alcohol Use
18.6 Left-Turning Accidents
18.7 Walking Speed
18.8 Handicapped Pedestrians
18.9 Nighttime Conditions
18.10 Winter Conditions
18.11 Social Factors
18.12 Child Pedestrians
18.13 Older Pedestrians
18.14 Roadway Design
18.15 Pedestrian Signs, Signals and Markings
18.16 Intelligent Transportation Systems and Pedestrian Safety
18.17 Safety Countermeasures
18.18 In-line Skating
18.19 Bicycle Safety
18.20 Bicycling Accidents
18.21 CyclistsØ Perception of Risk
18.22 CyclistsØ Behavior
18.23 Older Cyclists
18.24 Road and Environmental Factors
18.25 ITS and Bicycle Safety
18.26 Conclusion
References

Chapter 19: Left Turn and Gap Acceptance Crashes
Jeff K. Caird and Peter A. Hancock
19.1 Introduction
19.2 Definitions and Task Analysis
19.3 Left-Turn Crash Patterns
19.4 Gap Acceptance Crash Patterns
19.5 Motorcycles, Small Vehicles, Bicycles and Pedestrians
19.6 Age Differences in Left-Turn and Gap Acceptance Crashes
19.7 Driver Citations and Error
19.8 Left-Turn Driving Simulation and Field Studies
19.9 Gap Acceptance Studies
19.10 Perception of Oncoming and Cross Traffic
19.11 Signals and Intersection Design
19.12 Conclusions
Acknowledgments
References

Chapter 20: Single-Vehicle Accidents
Paul L. Olson
20.1 Introduction
20.2 Characteristics
20.3 Suicide?
20.4 Remedial Measures
20.5 Summary
References

Chapter 21: Why Witnesses to Accidents Make Mistakes: 
The Cognitive Psychology of Human Memory
Ralph Norman Haber and Lyn Haber
21.1 Introduction
21.2 Observing and Encoding Events into Memory
A. Observational point of view and perceptual adequacy
B. Allocation of attention
C. Bias in attentional focus
D. Knowledge, familiarity and expertise with the content of the event
E. Witness expectations and interpretation of the event
F. Alcohol and encoding
G. Summary of encoding of experience
21.3 Retention of Memory for Experienced Events
A. The inevitably wrong focus of autobiographical memory
B. Systematic changes in the content of memory with each repetition
C. Post-event information can create new (and potentially) false memories
21.4 Forgetting of Memory
A. Without the proper retrieval cues, recall may fail
B. Psychogenic memory blocks
C. Memory blocks can result from physical trauma
21.5 Improvement in Recall and Recovery of Memory
A. Additional retrieval cues improve recall
B. Psychotherapy, relaxation and hypnosis improve recall
C. Healing with time normally reduces amnesia following head injury
21.6 Memory for Everyday and Unusual Events Differ in Accuracy
21.7 Individual Differences: Do Some People Have Better Memories than Others?
A. Mnemonic systems and training to improve memory
B. Individual differences in suggestibility
C. The memory of children
D. Aging and memory
21.8 The Surprising Lack of a Relationship between Confidence and Accuracy
21.9 When Are Two Witnesses Better than One?
21.10 Summary
Endnotes
References

Chapter 22: Human Factors in Traffic Accident Litigation
Robert E. Dewar and Paul L. Olson
22.1 Introduction
22.2 The Profession
22.3 Hazards in Vehicle Operation
22.4 Designing for Whom?
22.5 Admissibility of Evidence from a Human Factors Expert
22.6 What the Human Factors Expert Has to Offer the Lawyer
22.7 Locating Suitably Qualified Human Factors Experts
Reference
Suggested Readings

About the Authors
Index

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