Traffic management not effective enough: Many drivers do not choose the fastest route

In addition to expanding the road network, more and more has been done in recent years to ensure that the existing traffic and transport system is better at satisfying mobility needs. ICT plays an important role in this respect. In order to deploy traffic systems more effectively, it is important to examine human behaviour. The choice behaviour of road users and the underlying thinking and decision processes are essential, concludes Jaap Vreeswijk in his doctoral thesis.

"How do road users react to changes that are the result of a new policy or a new measure? Think for example of new alternative routes or modes of transport, different traffic light settings or deteriorating traffic conditions on a road. These are important questions for road maintenance authorities," says Vreeswijk.

Large-scale estimation errors

In his doctoral research, Vreeswijk examined inertia in choice behaviour. This means that from the viewpoint of travel time a road user can make a better choice and can thus reduce this time, but nevertheless does not change the choice. Measurements show that in some cases up to 75% of road users do not choose the shortest route, with several possible reasons for this therefore. The exact reason for inertia in choice behaviour is often difficult to determine, but it is interesting to measure in what circumstances inertia occurs and to what extent. Vreeswijk has analyzed data from interviews, surveys, journey records and traffic systems. He looked at the choice behaviour of road users in relation to their perception of travel times for different routes and waiting times at traffic lights.

The analysis showed that road users make large-scale observation and estimation errors. In addition, certain differences or changes are not noticed or incorrectly classified, while time estimates are often coloured by preconceptions. For routes with a travel time of 10-15 minutes, the perception error was two to four minutes on average, depending upon the characteristics of the route and available choice alternatives.

The type of road, the directness of a route, the familiarity with the route, the strength of the preference for a route and the number of times that a route was already chosen, contribute to the degree of over- and underestimation of travel time.

Shortest route only chosen if there is a considerable difference

In his research, Vreeswijk noticed, however, that there are limits to inertia and perception errors. In the case of larger and clearer travel time differences almost all road users choose the shortest route and perception errors are smaller. An important observation is that the choice behaviour of road users can be better explained by perceived travel times than the actual travel times.

New opportunities

This knowledge about inertia provides new opportunities for controlling traffic. By taking account of inertia, inertia limits and perception errors, traffic management measures can be deployed in such a way that the acceptance of road users is maximized. For example, account does not have to be taken of side effects if the changes are not too great for road users. A number of examples in Vreeswijk's doctoral thesis shows that, depending on the circumstances, the total delay can be reduced by about 12%. Furthermore, by offering traffic and travel advice in a manner that more closely reflects the experience of road users, the effect of these measures is much greater.