Research Papers

Motorcycles are not invisible: Oncoming drivers misjudge when it is safe to turn

Version 1
Date added June 17, 2014
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Category 2014 CMRSC XXIV Vancouver
Tags Research and Evaluation, Session 3C
Author/Auteur Bertrand Sager, Elisabeth Kreykenbohm, Matthew R. Yanko, Thomas M. Spalek, David J. Froc, Daniel M. Bernstein, & Farhad N. Dastur
Stream/Volet Policy and Practice

Slidedeck Presentation Only (no paper submitted)

3C Sager_Motorcycles are not invisible


Motorcyclists are often involved in collisions where the driver of a car “looked but failed to see” the motorcycle before turning left across the motorcyclist’s path. Previous research focuses on perceptual factors that contribute to motorcycle inconspicuity, such as size and colour. This research often suggests countermeasures aimed at increasing motorcycle visibility, such as fluorescent jackets, headlight modulators, and daytime running lights. However, our research suggests that perceptual factors alone cannot explain this type of motorcycle collision, and that the role of those perceptual factors may be overestimated.  One hypothesis proposes that motorcycles may be difficult to detect due to their relatively small size, which might cause them to blend into their surroundings. Our first experiment, therefore, examined the influence of an object’s size on how frequently that object is detected in traffic. We employed a typical change-blindness paradigm, where cars, motorcycles, pedestrians, or irrelevant objects disappeared from a static picture of a driving scene. Participants were required to indicate whether and where an object disappeared. Lower detection rates were predicted for changes involving motorcycles compared to larger objects, such as cars, due to their small size. Inconsistent with the small-size explanation, participants detected changes involving motorcycles more often than larger objects, suggesting that one must look elsewhere to understand “looked but failed to see” collisions. An alternative explanation for the cause of these types of collisions is that drivers have greater difficulty in evaluating the motion of the motorcycle relative to other vehicles and as a result misjudge when it is safe to turn. This was tested in a second experiment, where we used a driving simulator to examine whether an oncoming motorcycle’s lane position could influence car drivers’ turning behaviour at an intersection. Drivers were seated at the wheel of a simulated vehicle and presented with a stream of oncoming cars and motorcycles. Their task was to indicate when they perceived a gap safe enough to make a left turn across the oncoming traffic. Our results indicated that drivers were more likely to turn in front of an oncoming motorcycle when it approached in left portion of its lane than when it approached in the right portion. This suggests that a motorcyclist’s lane position significantly influences a driver’s tendency to turn left across their path, even when it may be unsafe to do so. Taken together, these experiments suggest that “looked but failed to see” collisions may be due to judgement errors rather than the motorcycle’s conspicuity, as is generally believed.

Bertrand Sager, Elisabeth Kreykenbohm, Matthew R. Yanko, Thomas M. Spalek, David J. Froc, Daniel M. Bernstein, & Farhad N. Dastur