Paper presented at the 32nd Annual Southern African Transport Conference 8-11 July 2013 "Transport and Sustainable Infrastructure", CSIR International Convention Centre, Pretoria, South Africa.
The acceleration of light vehicles is often seen as an indicator of driver aggression. In automotive advertising the number of seconds it takes to reach a speed of 100 km/h can
be a major selling point for certain types of vehicle. The development of representative
and reliable speed profiles for vehicles accelerating from a stationary position, for vehicles
overtaking slower vehicles from a reduced speed and for vehicles exiting a horizontal curve are important parameters for engineers involved with the design and/or appraisal of the safety of roads. Importantly, this paper only deals with vehicles accelerating from a stationary position to speeds of 60 and 100 km/h. Most drivers of light vehicles do not utilise the maximum power available to them when accelerating a vehicle. The purpose of a recent study (Grobler, 2012) was to determine the proportion of the maximum acceleration that drivers are using when accelerating their vehicle within an urban environment.
In this study a limited number of drivers and vehicles were used to determine their acceleration from a stationary position. Since acceleration is decreasing from a maximum
value with an increase in speed up to a point where the maximum speed of the vehicle is
reached (Papacostas et al, 2005), it was necessary to calibrate a model for each test. The
results showed that drivers on average used about 55% of the maximum acceleration
available to them. This average and the distribution can be used in speed profile
calculation and programs that simulate the acceleration of vehicles. From the percentage
of individual drivers it was also possible to categorise the drivers into three different groups, namely standard, gradual and hard accelerators, which may be an indicator of driver aggression.
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