An Examination of Overtaking Judgments Based on Limitations in the Human Perceptual System: Implications for the Design of Driver-Assistance Systems - Digital Signal Processing for In-Vehicle Systems and Safety - page 228

17.2.5 Relative Direction of Approach
Gray et al. (2004) reported that the perceived velocity is relatively lower when the
observer and an approaching object are moving in opposite directions [ 32 ]. They
suggested that this leads to erroneous judgments of TTC. Such erroneous judgments
are critical during an overtaking maneuver because while overtaking, the self and
the oncoming car are typically moving in opposite directions, head on.
17.2.6 Motion Adaptation
Studies have reported effects of motion adaptation on certain judgments involved in
driving [ 33 ] and especially during overtaking maneuvers [ 11 ]. Based on driver
performance in a driving simulator, such studies showed that while driving on rural
roads, after drivers have been exposed to a nonchanging gap between the self and
the lead car for an extensive period of time, the thresholds for detecting a change in
gap between the self and the lead car or the oncoming car is higher [ 11 ]. In other
words, it takes longer for drivers to detect the change in distance between them and
the oncoming car when overtaking on rural roads. From a safety perspective, this is
quite dangerous. Congruent with such studies, Hegeman et al. (2005) reported that
most of the overtaking accidents in Netherlands occur on rural roads [ 22 ].
In sum, there are several limitations in the human perceptual system to
perceive distance and motion. Such limitations become more critical under
certain traffic conditions which might lead to erroneous judgments about distance,
velocity, and TTC with an oncoming car. At this point, to better understand the
complexity of an overtaking task and the additional demands it imposes on a
driver, it will be beneficial to compare and contrast an overtaking task with a
closely related type of driving task that has been widely studied; car following.
Idosointhefollowingsection.
17.3 Critical Differences Between an Overtaking Task
and Car Following
Inaccurate judgments during overtakingmaneuvers can result in overtaking accidents.
Similarly, inaccurate judgments during car following can result in rear-end collisions.
Twenty-five percent of accidents on the road are rear-end collisions [ 34 ]. Therefore,
several studies have investigated the types of perceptual judgments that are critical
for safe car following. For example, studies have investigated deceleration judgments
[ 16 , 18 , 35 ], headway estimation [ 36 ], and TTC judgments [ 1 , 2 , 6 , 14 , 17 , 18 , 29 , 31 ,
34 - 43 ] during car following. Interestingly, all judgments that are crucial for safe car
following are also critical during overtaking maneuvers. However, there are three