Practical implications

Although the current work focussed on only one element in traffic behaviour (lane keeping), the findings also have practical implications for traffic safety in general. In this section we discuss how the current findings can add to the three E’s of injury prevention (i.e. Enforcement, Engineering and Education), and elaborate on how current findings can be of use for future research.

 Enforcement

Current findings suggest that learner bicyclists lack the cognitive skills necessary to focus on the appropriate information, and to process it efficiently into adequate steering responses. Unfortunately, based on the current results it is difficult to say to what extent cognitive functions such as attention and processing speed should be developed in order to behave safely in traffic. If the development of these functions could be linked to the development of cycling skills and traffic behaviour, these might serve as a guideline for when parents could let their children cycle independently. Likewise, investigating the decline of these cognitive functions in elder bicyclists might also provide insights into why this group is accident prone.

Furthermore, the findings emphasize that it is indeed necessary to adapt traffic rules to children. Especially in regions such as schools and playgrounds, traffic rules should take the limited capabilities of children into account. Slowing down other traffic, separate the car traffic from pedestrians and cyclists with (natural) barriers, and easy to understand traffic rules are advisable in these areas.

 Engineering

The visual behaviour of both adults and children was strongly dependent of task, and environmental factors. At complex intersections, it is therefore important to keep the task and environmental constraints as low as possible. This way the task demand of lane keeping is kept to a minimum, and attention can be devoted to scanning the environment for hazards and/or other important information (such as traffic signs). In practice, this implies that on complex intersections, road quality should be high, cycling speed reduced, and light conditions optimal. Tram tracks at bicycle crossroads, for example, could possibly distract the bicyclists from upcoming traffic, and hinder the perception of anticipatory cues.

That bicyclists were also found to direct most of their attention to the inner edge or middle of the road while cycling a bend suggests that they have few spare attention to direct to the environment. Detecting traffic lights and signs in, or immediately after, a sharp turn might therefore be problematic. These constraints on visual behaviour should therefore be taken into account when designing new road infrastructure.

187  Education

When confronted with challenging steering tasks, children adopt a different visual-motor strategy. Since this is probably due their limited capabilities, it is important that traffic education acknowledges these limitations. It might be better to teach alternative visual- motor strategies to children as long as they are not able to imply adult-like visual-motor strategies efficiently. Children should therefore be encouraged to adopt simpler and safer visual-motor strategies, characterized by simple step-by-step actions.

However, it is still likely that children also make hazardous decisions because of a lack of

experience in traffic situation. The current work only investigated visual behaviour in

function of lane keeping. Regarding hazard perception, children might be able to detect cues as fast as adults, but might lack the experience to do so, and to interpret the information adequately. Hazard perception tests for bicyclists (such as in appendix A), could provide valuable insights into the situation awareness of children. These tests might lead to innovative traffic education tools such as hazard perception games.

 General implications and future research

As was mentioned before, the methodological study done in the current thesis can be of use for other researchers. The fixation-by-fixation analysis method was proposed as a quick- and-dirty method to obtain general distribution of visual attention. Faster analysis methods allow researchers to analyze more data, and therefore contribute to the insights into visual behaviour during various tasks. Nevertheless, to guarantee the control of external variables, many experiments are still conducted using video stimuli and remote eye trackers instead of head-mounted eye trackers. The validity of these video-based experiments should be further tested in similar ways as was done by Foulsham et al. (2011) and Dicks et al. (2010). Furthermore, with improving eye-tracking technology it should be possible to measure

actual gaze distance. This could provide a more accurate measurement of look-ahead

distance.

There is still few knowledge about the visual behaviour during other traffic tasks such as hazard perception. However, future research should not only focus on investigating single traffic tasks, but also the integration of multiple tasks. In traffic situations, lane-keeping, hazard perception, navigation, etcetera, are often carried out simultaneously. Therefore, being able to efficiently multitask is an essential aspect of safe traffic behaviour. Nevertheless, the current findings already provide insights into how gaze is distributed during different bicycle steering tasks, and how it changes with different constraints. Future research should investigate how these lane keeping tasks interact with other traffic tasks.

Whereas the current work focussed on visual information, this is not the only source of information in traffic. Auditory signals can also provide important anticipatory cues, but can also be a source of distraction. Unfortunately, the integration of multiple sensory stimuli in traffic environments is poorly documented. A focus on the integration of visual and auditory

General discussion

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stimuli could shed more light on the issue whether listening to music reduces the alertness to other important cues.

In general, bringing together the visual behaviour during walking, biking and car driving added to the general understanding of the visual control of locomotion. We suggested that the strategy that is used to detect heading direction (egocentric or optic flow strategy) might determine the preferred direction of gaze. More insights into how heading direction is determined during various traffic tasks might clarify the visual behaviour of car drivers and bicyclists when steering through a curve.

Finally, the constraints model that was proposed could be used to predict how various factors will affect the visual behaviour of traffic participants. Nevertheless, further testing is necessary to assess the validity and usability of this model.

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