Assisting the older driver - SWOV

Intersection design and the older driver
United States of America, and the infrastructure in these states is rather
different from the one in Europe, all measures have been thoroughly
screened with the help of Dutch engineers (Davidse, 2002). The measures
were screened on the possibility and desirability to translate them to the
European situation. Only those measures and recommendations that were
judged to be suitable for the European situation, that were consistent with
the Sustainable Safety policy in the Netherlands, and that were related to
intersections in built‐up areas are included in the next paragraphs.
5.3.2. Intersection design
Intersections can be defined as traffic situations that require complex
judgements of speed and distance, and simultaneous activities under
pressure of time. Older adults generally have more difficulties in meeting
these requirements than younger drivers have (Chapter 2). Intersection design
elements that may be beneficial to older drivers in this respect are (Staplin,
Lococo, Byington & Harkey, 2001):
• Elements that provide a good and early view of the intersection;
• Elements that assist the driver in making a left turn;
• Roundabouts.
View of the intersection
At the approach of an intersection, the view of other traffic approaching the
intersection is largely determined by the angle at which crossing streets meet.
The optimal angle is one of 90 degrees. A smaller angle makes it more
difficult to get an overview of the intersection and to notice other road users.
Road users can compensate for these difficulties by turning their head a bit
more. However, as older adults generally have restricted head and neck
mobility, they will have more trouble with intersections where streets meet at
a small angle. Therefore, a right angle junction is in particular important for
older road users.
Apart from the fact that older adult drivers have more trouble overlooking
the intersection because of a restricted mobility of head and neck, they also
need more time to react (increased perception‐reaction time). A restricted
view of the intersection, not only because of a small angle between the
intersecting roads, but also as a result of shrubs, trees and buildings blocking
the view of the intersection, leaves the driver little time to overlook the
intersection and therefore also little time to react. The resulting pressure of
time probably causes more problems for older drivers than for younger
drivers. Therefore, a shorter sight distance or stopping sight distance
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