Assisting the older driver - SWOV

Effects of intersection design on workload and driving performance
road position or trajectory, by communicating with other drivers, or – at an
earlier stage – by choosing an easier route or better driving conditions (e.g.,
clear weather, daytime). Apart from the (older) driver, other road users can
take compensatory actions as well, such as getting out of the way, thereby
avoiding a collision. A third way of reducing the chance that collisions will
occur is by lowering task demands through an adjusted design of the
infrastructure and/or vehicle adjustments and technologies. The present
study evaluates the possibilities of lowering task demands through
adjustments to the design of intersections. A related study discusses the
merits of in‐car driver assistance systems (Davidse, Van Wolffelaar,
Hagenzieker & Brouwer, 2007; see also Davidse, 2006).
Using literature on task difficulty, information processing, ageing and
driving (e.g., Fuller, 2000, 2001; Hendy, East & Farrell, 2001; Brouwer, 2002b),
Davidse (2007) has attempted to describe the task difficulty of passing
intersections. That is, crossing or turning left or right at them. She expects
that the difficulty of passing an intersection is a combination of 1) the
complexity of the traffic situation, 2) the availability of a proper mental schema,
and 3) whether or not the driver has to take a decision with regard to road
users that are about to cross his path (e.g., side‐street or not, priority
regulation or traffic lights that guarantee a protected left‐turn). More
specifically, she expects that the task of passing an intersection will only be
difficult if the traffic situation is complex and the driver cannot bring his
experience (and schemata) to the job and the driver has to decide on how to
deal with traffic that is about to cross his path.
Davidse (2007) also defined the complexity of a traffic situation. She expects
complexity to increase with 1) the amount of information that has to be
processed (e.g., number of lanes and traffic signs, presence of pedestrian
crossings), 2) a reduction of the quality of the information (e.g., visibility of
signs and pavement markings), and 3) the presence of time pressure (e.g.,
presence of trees, houses or cars that block the view of the intersection and
reduce the time left to anticipate on what is coming). As such, complex
situations put a severe strain on the sensory, perceptual and cognitive
capacities of the driver. These capacities are often reduced in the older age
group (see e.g., Brouwer & Ponds, 1994; Fisk & Rogers, 1997). Examples are
decreased divided and selective attention, reduced contrast sensitivity, and
reduced speed of information processing. As a result of these functional
limitations, the complexity factor may play a more important role in the task
difficulty of passing intersections by older drivers than it will in the task
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