1. ABS, Crash Speed and Injury Severity
Jim Ouellet
Motorcycle Accident Analysis
Playa del Rey, CA
State Motorcycle Safety Administrators
National Motorcycle Training Summit
Sacramento, California
September 12-16, 2018

2. ABS
What ABS and Autonomous Emergency Braking (AEB) can do is pretty limited.
In motorcycle-car crashes, better braking can delay arrival at Point of Impact (POI).
Often there’s too little time to prevent a crash, only to reduce speed
Is that enough?

3. Collision Avoidance

4. Time From Precipitating Event to Impact

5. “At-Risk Zone Locations for Hypothetical Car Left Turn from Stopped Position

6. Hypothetical “At Risk” Zones for a Car Left Turn from Stopped
Collision unavoidable
Collision avoidable with braking g
Collision avoidable with braking < .4g
Collision occurs if the rider brakes

7. Hypothetical “At Risk” Zones for a Car Left Turn at Constant 13 mph
Collision certain
Braking at g required
Braking at < .4g required

8. “At Risk” Zones for a Hypothetical Car Crossing From the Near Curb

9. Variables that Affect Location and Make-up of “At-Risk” Zones
Motorcycle speed and lane position
Rider reaction time
Motorcycle deceleration rate
Car type of maneuver
Car speed
Car evasive action

10. Some Take-Aways
The point is that any time another vehicle violates a motorcycle right-of-way, an “at-risk” zone for a possible crash is present.
The ability of braking to prevent a crash is limited by the exact location of the motorcycle within the “at-risk” zone.
The area in which high rates of deceleration can actually prevent a crash is much smaller than the total “at-risk” zone.
Improved braking also creates a small zone in which a rider could brake effectively enough to be hit by a car he could have avoided by not braking.

11. Crash Speed and Rider Injury Severity

12. Cumulative Percent Distribution, Motorcycle Crash Speed x Rider Medical Treatment, Hurt Study

13. A quick primer on correlations
Temperature: Fahrenheit vs. Centigrade
Most Severe Somatic Injury vs. Somatic Injury Severity Score
R = 1.0
r = 1.0
r = .82
Temperature vs. Somatic Injury Severity Score
r = -.11
r = .32, r2 = .102
Crash speed : Somatic ISS

14. Correlations of Injury Severity with Crash Speed & Crash Speed Squared, Hurt Study
Injury Measure
Pearson r correlations
Spearman rho correlations,
Vcrash or V2crash
Crash Speed
(Vcrash)
Crash Speed Squared (V2crash)
Injury Severity Score (ISS)
.374
.382
.361
Somatic ISS
.325
.340
.318
Most Severe Somatic Injury
.319
.305
.300
Most Severe Head-Neck Injury
.337
.323
.279
Most Severe Brain Injury
.307
.291
.284
Medical Treatment
.390
.364
.378

15. These linear correlation coefficients –generally about. 3 -
These linear correlation coefficients –generally about mean that crash speed, by itself, accounts for about % of the variation in rider injury severity.

16. Scatter-plot of Most Severe Below-the-Neck Injury
versus Motorcycle Crash Speed, Hurt Study

17. Box-plot of Most Severe Below-the-Neck Injury versus Motorcycle Crash Speed, Hurt Study

18. Scatter-plot of Most Severe Somatic Injury versus Motorcycle Crash Speed, Thailand

19. Box-plot of Most Severe Somatic Injury vs
Box-plot of Most Severe Somatic Injury vs. Motorcycle Crash Speed, MAIDS

20. Why Are the Correlations Between Crash Speed and Injury Severity So Low?

21. Motorcycle & Rider Impacts on the Side of a Moving Car, Perpendicular Impact3 4 5 2 1

22. Motorcycle Crashes Have a High Level of Randomness – Unpredictability – in Injuries

23. Expected Effects of Improved Braking Systems
Some crashes will be prevented.
Average motorcycle crash speed in a population of crashes will be lower
Injury severity in a population of crashes will generally be lower
The effect on injuries in an individual crash will be unpredictable.

24. The mild effect of improved braking on injury severity is the reason why the best – the only – effective strategy is to prevent motorcycle crashes entirely.

25. Yet motorcycles are mostly neglected in the development of a connected intelligent traffic system.

26. Thank You