Driver Attention & Braking

Q&A related to Driver Factors in Crash Reconstruction
MSI
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Driver Attention & Braking

Post by MSI »

From NAPARS FaceBook Page:
Divided Attention & Braking.
  • Remember those research studies that showed about 80% of people rated their own driving skills as "above average"? Turns out, we often expect better than average performance from other people, too.
    In this case, I'm thinking of how well drivers perform at "stopping as rapidly as you safely can" when there are multiple things competing for their attention. Muttart et al. (including 4 NAPARS members) showed in a 2011 paper that when there were pedestrians present taking some of their attention, drivers only braked at an average rate of -0.55g. The standard deviation was 0.12g, meaning that when asked to stomp the brake pedal, 68% of the participants generated between -0.43g and -0.67g. Both of which are lower than most of us would have anticipated, I expect.

    When attention was split among multiple potential hazards, people simply couldn't stomp the pedal as hard. Expecting them to always make the -0.76g that the car and tires can usually generate is utopian and unreasonable. That's not to say that nobody ever makes big numbers but rather that normal people might not. We've all seen people lock their wheels before an impact, so it can happen, right?
    Motorcycle riders had the same problem. Motorcycles are pretty much all capable making nearly -1g. In parking lot "best stop" events, riders actually get closer to -0.7g. But when there were additional hazards to attend to, riders got just -0.44g (see table 2 for full details).
    table 2 muttart.png
    table 2 muttart.png (84.95 KiB) Viewed 4927 times
    We are often not as good as we think, and neither are other people. Food for thought when considering an analysis that hangs on what we expect someone else to have been able to do in an emergency.
See paper:
INFLUENCE OF RIDING EXPERIENCE ON GLANCE BEHAVIOR, BRAKE RESPONSE TIME AND DECELERATION RATES BY DRIVERS AND MOTORCYCLISTS
Muttart, Fisher, et al
  • Summary: The focus of the research was to address the crash avoidance behaviors of drivers versus motorcyclists. Avoidance tasks include, attention maintenance and hazard anticipation measured with glance behaviors, and hazard mitigation measured with response times and deceleration. Specifically, where might the driver behavior be similar or different than that of a motorcyclist? The performances of 23participants were analyzed while they drove a car and rode a motorcycle over the same low-volume, open roads. Participants wore eye-tracking equipment used to record eye-glance information while the motorcycle and car were instrumented with an on-board accelerometer and GPS apparatus. Operators also responded by braking quickly to a stop when an LED, mounted in front of them, was illuminated. Motorcyclists spent less time glancing toward the road ahead and made fewer last-glances toward the direction of most threatening traffic before turning when riding the motorcycle, as opposed to when driving a car. Additionally, motorcyclists’ response times were similar to those when driving, yet motorcyclists decelerated less sharply compared to drivers. These results suggest that riders may be exposing themselves to unnecessary risk. Specifically, motorcyclists frequently failed to make proper glances and practice optimal riding techniques. The implication of these results relative to a training curriculum is discussed.
Figure 3 Muttart paper.png
Figure 3 Muttart paper.png (110.81 KiB) Viewed 4927 times