Assisting the older driver - SWOV

Effects of a driver support system on workload and driving performance
For those that did stop, waiting position did not differ between support
conditions (F(1, 23) = 0.409, p = 0.529, η 2 = 0.017). Looking at all participants –
those that did and did not stop – driving speed on the intersection tended to
be lower (1.39 km/h) when driving with the support system installed than
when driving without the support system installed (F(1, 36) = 3.886, p = 0.056,
η 2 = 0.097). Differences between age groups were not significant, neither for
driving speed nor for waiting position.
Safety of decisions
Mixed between‐within analyses of variance for deceleration measures
Acc_Pre and Acc_Crit showed that messages regarding obstructed view of
the intersection only affected the proportion of unsafe decisions to pass these
intersections (Acc_Crit). This proportion was smaller during drives at which
participants were supported than during drives at which no support was
available (see Table 8.12 for means and standard errors; F(1, 36) = 4.680, p =
0.037, η 2 = 0.115). The interaction effect of functional age and driver support
was also significant (F(2, 36) = 4.371, p = 0.020, η 2 = 0.195). It turned out that
functionally middle‐aged participants had by far the largest decrease in the
proportion of unsafe decisions (0.32 without support versus 0.04 with
support). The effects of driver support on the proportion of unsafe decisions
made by functionally young and functionally old participants were not
significant.
Acc_Pre
(lower values = less safe decisions)
Acc_Crit
(higher values = fewer safe decisions)
Mean Standard error Mean Standard error
View of the intersection
No support
Support
‐ 0.446
‐ 0.309
0.203
0.236
0.250
0.145*
0.034
0.030
* p < 0.05
Table 8.12. Means for safety of view of the intersection, without and with driver support.
8.3.6. Messages regarding changed speed limits or one‐way streets
Messages regarding changed speed limits were sent if the limit had changed
from 50 to 70 km/h and the driver had not changed speed accordingly.
Driving speeds and the appropriateness of sending a message were checked
on three road stretches. The number of messages per participant varied from
1 to 3. Whereas 80% of the functionally young and 90% of the functionally
177