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4
Driver Information
Acquisition and Processing
INTRODUCTION
Driving a vehicle is an information-processing activity. During driving, the driver continuously
acquires information from various senses (vision, hearing, tactile, vestibular, kinesthetic, and olfac-
tory), processes the acquired information, makes decisions and takes appropriate control actions to
maintain vehicle motion on the roadway, and navigates to an intended destination. Vision is essen-
tial for driving. It is estimated that during driving, a driver receives over 90% of the inputs from his
or her eyes. Therefore, in this chapter, we will begin with understanding the structure of the human
eye and the capabilities of the human visual system (visual capabilities are also called human visual
functions). The acquired visual information is sent to the brain, and the brain processes the informa-
tion along with the information stored in the memory to make numerous decisions.
It is important to understand that most driver failures occur due to failure in obtaining the neces-
sary information in the right amounts at the right time and the right place. When a driver is asked
to describe how he or she got involved in an accident, the most common type of responses are the
following: “I did not see the target (a pedestrian, a car, a curve, a sign, etc.)” or “I did not realize
that the other vehicle was approaching so fast, or I misunderstood the situation.Thus, the vehicle
designer should constantly think about designing the vehicle to reduce the chances of driver infor-
mation-processing failures and errors.
On many occasions, the driver may nd that he or she has too many tasks to do within a very
short time interval due to trafc, roadway situations, state of his or her vehicle, and/or other non-
driving tasks or distractions (e.g., answering a cell phone). Understanding the various demands
placed on the driver and how the driver should prioritize and time share between different tasks are
also areas of great importance to the vehicle designers.
IMPORTANCE OF TIME
Understanding the amount of time that the driver needs to perform different tasks is probably the
most important concept in designing the driver–vehicle interface. Most drivers take about 0.51.2
s to read speed from an analog speedometer with a moving pointer on a xed scale (Rockwell
etal., 1973). To view the objects in a driver’s side-view mirror, most drivers will make about 0.8- to
2.0s glances. In operating more complex devices such as radios and climate controls, the drivers
typically make two to four glances; and each glance takes about 1.0 s in performing tasks such
as selecting a radio station, changing temperature, or changing fan speed (Bhise, 2002; Jackson
etal., 2002).
A vehicle traveling on the highway at 100 km/h (62 mph) is equivalent to traveling 28 m (90 ft)
per second. Thus, when a driver takes time away from the forward scene to make a 1-s glance, the
vehicle travels 28 m on the roadway. If the driver takes a glance for more than 2.5 s time away from
the roadway to perform other tasks, the driver will have difculty in maintaining his or her vehicle
within the lane. And if the driver takes more than 4.0 s away from the road, he or she is almost
guaranteed to drift outside the driving lane (Senders etal., 1966).
Thus, it is important to design equipment inside the vehicle that drivers can use with glances no
longer than about 1.5 s, and the total number of glances away from the road should be as few as

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