Present and future assisting systems are meant to support the
driver in coping with the difficulties of driving. The design of
the system properties and their limits helps to influence on the
road-driving behavior directly and through teach-back effects. On
the other hand, there is a potential risk of negative effects on
the safety due to a division of tasks between the driver and the
technical system. Bearing this in mind, the Automotive Engineering
Department and the Department of Ergonomics of Darmstadt University
of Technology were engaged by BMW AG to investigate the distance
behavior of vehicles with and without ACC (Adaptive Cruise Control)
which is used to control the speed and distance maintained to
vehicles ahead and turning into the traffic.
This trial was made with the aim of a representative and
objective investigation of the behavior of the total system of
driver-vehicle-environment in road traffic. A total of 50 rides
were made on select routes which were carefully analyzed with
regard to relevant characteristics such as road type, number of
lanes and speed limits. In order to avoid any acclimatization
problems the testing persons were familiar with the used vehicle
type and were selected on the basis of typical distribution of age
and mileage traveled. Special emphasis was put on an even
distribution of driving experience with and without conventional
cruise control. In addition to the video equipment necessary for
recording the traffic situation, the test vehicle was fitted with
extensive equipment to record the actions of the driver, the
driving parameters and distances and speeds relative to the road
users ahead. The complexity of traffic situations necessitated
classification in advance. The classification with regard to
comparable situations was made, for instance, by means of videos
which, in connection with the vehicle data, also served to define
the characteristic moments of time and relevant parameters.
On this basis an objective analysis of distance behavior is made
from the safety aspect. The comparison drawn between the actually
set and the specified distances reveals the conflict of aims
between the compliance with legal regulations and actual traffic
conditions. The driver's behavior, shaped by their personal
motivation differs from the characteristics of the system.
Potential methods are sketched out for improving traffic safety by
using ACC.