Assisting the older driver - SWOV

Assisting the older driver
6. Effects of intersection design on workload and
driving performance of older drivers 6
In a driving simulator, ten older (70–88 years) and thirty younger (30‐50 years) drivers were
guided across intersections that differed in terms of a) layout (3‐way intersection, 4‐way
intersection, dual carriageway, or roundabout), b) priority regulation, and c) view of the
intersection. Hypotheses with regard to the factors that influence the difficulty of passing
intersections by older drivers were tested by comparing workload and driving performance
between different types of intersections and between different age groups. Intersection
layout turned out to be the best predictor of variations in workload. Three‐way intersections
that only had a side‐street at the left‐hand side of the driver turned out to be the easiest
intersections to pass, whereas four‐way intersections with dual carriageways were the most
difficult to manage. Workload was higher for older drivers for all types of intersections. No
interaction effects were found. Results on driving performance were less conclusive.
6.1. Introduction
Research on crashes involving older drivers – those aged 75 and above – has
shown that the crash type that is most common in this group occurs while
they are turning left (Aizenberg & McKenzie, 1997; Davidse, 2000; Hakamies‐
Blomqvist, 1993, 1994c; McGwin & Brown, 1999; OECD, 2001; Zhang et al.,
1998). Possible causes of these crashes are the intersection design, functional
limitations of the individual and the incompatibility of these two factors.
This study focuses on the role that incompatibility of intersection design and
functional limitations plays in the driving performance of older drivers. The
incompatibility of intersection design and functional limitations boils down
to the extent to which the intersection design takes into account the
functional limitations of a part of the population of road users. To study this
incompatibility, we will make use of the concept of task difficulty.
Fuller has described the concept of task difficulty in detail (Fuller, 2000, 2001,
2005). According to his model, task difficulty is the result of a confrontation
of capabilities and task demands. If the capabilities of a road user are higher
than the task demands, the task will be easy and the driver will be in
command of the situation. However, if task demands are higher than his
capabilities, the task will be too difficult and loss of control will occur.
Fortunately, the driver has several opportunities to keep or regain control
(i.e., to lower task difficulty): by lowering his driving speed, changing his
6
An abbreviated version of this chapter will be submitted to a relevant scientific journal.
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