Assisting the older driver - SWOV

Current state of the art: crashes and injuries
fatality rate. Vehicle measures such as Side Impact Protection systems do
indeed intervene in the vulnerability factor (Mackay, 1988; Maycock, 1997).
They are not so much aimed at a reduction in the number of crashes (also
known as primary safety) as they are at limiting injury severity if a crash
happens (secondary safety). Moreover, they are specifically aimed at
reducing injuries in crashes that are over‐represented among older drivers:
side‐collisions at intersections (see Section 1.3).
1.2.3. Crash responsibility
A second comment that can be given on Koornstraʹs remark has to do with
the relative improvement (i.e., more so than for other age groups) that can be
achieved in terms of primary safety; a reduction in the number of crashes.
Various studies have shown that older drivers more often appear to be
ʹresponsibleʹ for the crashes they are involved in (Cooper, 1989; Verhaegen,
Toebat & Delbeke, 1988). If that is the case, crash involvement of older
drivers can be lowered to a level that is closer to the average driver by
finding out what the causes of their crashes are, and by producing measures
that prevent such crashes from happening. Suppose, for example, that
crashes for which older drivers are responsible are predominantly caused by
functional limitations that are more common in the older age group.
Assistive devices may then be developed which may prevent these crashes,
resulting in a reduction of the crash involvement of older drivers that is
larger than the one obtained for younger drivers.
In order to estimate the relative responsibility of drivers of a certain age
group for the crashes they were involved in, Cooper (1989) divided the share
that drivers of that age group had in the total number of legally responsible
drivers by the share that drivers of that age group had in the total number of
not‐responsible drivers. For the youngest age group (< 25 years old) he found a
ratio of 1.5, for the age groups up to 65 years of age ratios were below 1
(around 0.80), whereas for the age groups of 65 and above ratios increased
from 1.20 for the 66‐70 year olds to 5.67 for the 86‐90 year olds. Verhaegen,
Toebat and Delbeke (1988) found slightly different ratios. They found lower
ratios for the youngest age group (0.95) and higher for the age groups from
40 to 60 years old (1.00). These differences are possibly the result of different
sample compositions. In Cooperʹs study, injury crashes as well as Material
Damage Only (MDO) crashes were included, whereas Verhaegen, Toebat
and Delbeke only included MDO crashes.
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