Distraction Impact Analysis: A Targeted Approach to Crash Causation
JEFF MUTTART, PH.D., ACTAR ACCREDITED #96
DRIVER RESEARCH INSTITUTE
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Jan 2024
MEET TEACHING OUR TEAM
JEFF MUTTART, PH.D.
President
SWAROOP DINAKAR, MS
Director of Consulting
TIM MALONEY, MS
Scientist: Retired Police Sgt.
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Classes Taught and Licensed Users of RESPONSE®
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1. Limitations of Current Approaches
The Problem
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EXPERT WITNESSES:
NEED “SUBSTANTIALLY SIMILAR” COMPARISONS
CANNOT ASSUME “AVERAGE DRIVER”
The Problem
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MANY SIMULATOR STUDIES: DELAYED RESPONSE TIMES
MOST NATURALISTIC STUDIES: REDUCED CRASH RISK
The Problem
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Performance costs:
0.01 s. or 2 s.?
For all crash types & All Usages?
FARS:�Front-to-Rear��86% of “distracted” events were not from direct evidence��We need a better �cause - effect
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Task | Number | Percent Objectively categorized |
Occupant | 151 | 14% |
Moving object | 13 | |
Talk or Listen | 108 | |
Mobile | 133 | |
Adjust radio | 43 | |
Components / Controls | 75 | |
Use/Reach for device | 117 | |
Outside person / object | 267 | |
Eating/Drink | 42 | |
Smoking | 7 | |
Another mobile device | 143 | |
No driver | 401 | |
Distraction / Inattention | 193 | 86% |
Distraction / Careless | 2 | |
Careless / Inattention | 6 | |
Distraction Unknown | 658 | |
Inattention Unknown | 1284 | |
Not Reported | 3406 | |
Lost in thought | 5 | |
Other distraction | 22 | |
Unknown if distracted | 723 |
N = drivers (7370)
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2. Crash Types Distinctly Different Events
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1 bit = log2 1.0
CRASH SAFETY SOLUTIONS, LLC 2021
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Comparative Probability
Source: 2nd Strategic Highway Research Program
More Probable = Less Uncertain = �Faster Response Times
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More info to process
More uncertainty
Less info to process
Less uncertainty
Faster response
Shannon Bits of Information(x) = -log( prob(x) )
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Source: Muttart and Dinakar, 2022
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3. Dosage, Tolerance, Task Framework
Crash Types are Alike
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Dosage, Tolerance, and Task Framework
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Vulnerable Road Users are Not Alike
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Secondary Tasks are Not Alike
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4. Methodology for Evaluating Distraction
Dosage, Tolerance, and Task Framework
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Tolerance:
Classical
Case-Control
Scientific Approach
How drivers responded to similar baseline task in research
Driver’s Performance
We need a method
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Our solution: Standardizing the research results
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Source: Horrey, & Wickens, 2006
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First Author Name | A/V | HF | HH | COG | VM |
Alm | | | | 2.71 | |
Brookhuis | | 0.00 | | | |
Benedetto | | 0.03 | 0.02 | | |
Chisholm | | 0.00 | | | |
Cole | 0.55 | | | | 0.64 |
Cooper | | | -0.48 | | |
Drews | | | | | 0.56 |
Drews | | | | | 5.21 |
He | | | 0.25 | | 0.43 |
Ishida | 0.06 | 0.32 | 0.19 | | |
Lamble | | | | 0.61 | 0.61 |
Lin | 0.42 | | | 0.85 | |
Nilsson | | | | 0.00 | |
Mohoebbi | | 0.88 | | 0.94 | |
Muttart a(cue) | | | | 0.46 | |
Muttart a | | | | 0.03 | |
Muttart b | | | | | 0.96 |
Ranney | | | -0.56 | | |
Sawyer | | | | | 1.00 |
Smiley | | -1.37 | | | |
Strayer | 0.41 | 0.62 | 1.28 | 1.90 | |
Terry | | | | 0.82 | |
Xu | | | | | 2.17 |
Shinar (Days 1-3) | | -0.50 | | -0.50 | |
Weaver | | | | 0.00 | |
Metz | -0.34 |
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|
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Lee |
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| 1.86 |
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Standardized Brake Response Times
Not significant
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Standardized Brake Response Times
Slower than 58% of baseline responders
Quartile
Not significant
Z
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Standardized Brake Response Times
Slower than 47% of baseline responders
Quartile
Not significant
Z
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Standardized Brake Response Times
Slower than 54% of baseline responders
Quartile
Not significant
Z
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Standardized Brake Response Times
*Slower than 75% of baseline responders
Quartile
significant
Z
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Standardized Brake Response Times
*Slower than 93% of baseline responders
Quartile
significant
Z
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| A/V | HF | HH | COG | VM |
Median | 0.41 | 0.01 | 0.11 | 0.61 | 0.96 |
75th percentile | 0.42 | 0.24 | 0.20 | 0.85 | 1.67 |
25th percentile | 0.14 | 0.00 | -0.10 | 0.03 | 0.63 |
Table 6. Z-score increase or decrease in PRT for median, 25th percentile, and 75th percentile responder. For responses to a LV while using a cell phone and engaged in one of five secondary tasks
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Drivers’ BRT
1. Significantly greater when engaged in Cognitive or Visual/manual secondary tasks
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Non-Standardized Response Times
L2 Vehicle studies
Sec.
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Non-Standardized Response Times
L2 Vehicle studies
Not an emergency response
Sec.
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Non-Standardized Response Times
Slower than 50% of baseline responders
L2 Vehicle studies
Sec.
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Non-Standardized Response Times
*Similarly slow response as cognitive with no L2
L2 Vehicle studies
Sec.
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Non-Standardized Response Times
*Slower than 93% of baseline responders
Quartile
L2 Vehicle studies
Sec.
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Not standardized – general finding
Other findings: Handheld or Hands-Free on PRT
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+
NS
NS
NS
Conversation
Significant?
Even texting did not reach significance – 85% < 1.8 s TTC
Definition of distraction for Crash Reconstruction
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Driver Distraction occurs when a driver is involved in a non-driving-related task that results in a response that is inferior to the baseline responses observed for similar tasks.
A crash related to driver distraction takes place when this decline in response quality leads to a crash that would not have happened under typical response conditions.
1. Take caution in “distraction” data
2. L2 is generally associated with delayed response
3. 2nd tasks are cues or distractions only when associated with behavior changes associated with a change in the outcome
Can all response types be crash surrogates?
Other resources
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For night photos
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Copyright
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Source: Muttart and Dinakar, 2022
Drivers exhibit “Wait & See”:
Head-on
LTAP-OD > 3s. TTC
Turn into Path (RTOR)
Red light runners
Uncertainty = inverse of probability
Tap table when a circle appears
When Probability = 100%
Reaction time approaches 0 s.
Reaction time is longer with more uncertainty
GOOD!
KEY TAKEAWAYS
& IMPLICATIONS:�