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 226

17.1.1 Identifying the Problem

Drivers perform maneuvers like lane changes, left and right turns, car following,
and overtaking, and it is important to avoid collisions during such maneuvers. It has
been suggested that an overtaking maneuver is especially a complex one that has a
high probability for human error [ 19 ]. Although studies suggest that an overtaking
maneuver is a complex task, the sources of visual information that guide such
maneuvers are largely unknown. Past research suggests that drivers use different
strategies to complete an overtaking maneuver [ 11 ]. Also, it has been noted that
drivers make erroneous judgments about the temporal gap required to complete a
safe overtaking maneuver [ 20 ]. Also, drivers are typically not accurate in judging
the distance required to pass [ 11 , 21 ]. In short, first, it is important to clearly identify
the sources of visual information that drivers use during an overtaking maneuver.
Then, it is essential to examine the effectiveness of such sources. If the effective-
ness of the visual information is low, then the quality of the consequent perceptual
judgments will be poor. In contrast, if the effectiveness of the visual information is
high, then the quality of the consequent perceptual judgments will be better.
An important contribution from DAS can be in enhancing the effectiveness of
visual information.

17.2 Visual Information that Drivers Rely
on During Overtaking Maneuvers

A recent study reported that after drivers decide to overtake, they determine whether
the distance until the first oncoming car is sufficient to initiate the maneuver.
Additionally, it was suggested that since the self, lead car, and oncoming car are
in motion, it is essential to perceive the velocity and time-to-contact (TTC) informa-
tion of the cars before initiating the overtaking maneuver and while passing [ 22 ].
Furthermore, the oncoming car might be accelerating or decelerating. Therefore,
drivers have to accurately judge the rate of change of velocity of the oncoming car.
In short, judgments about distance, velocity, acceleration, deceleration, and TTC are
critical during overtaking maneuvers. Needless to state, an overtaking maneuver is
perceptually more demanding to a driver because he or she has to make such
judgments for more than one vehicle - the lead car and the oncoming car. Next,
I examine the effectiveness of such visual information.

17.2.1 Time-to-Collision

Lee (1976) noted that the time-to-collision with an approaching vehicle is optically
specified by the ratio of the angular extent (e.g., visual angle subtended on the
driver's eye by the front bumper of the oncoming car) to the rate of change of that