The opinions expressed in the studies are those of the consultant and do not necessarily represent the position of the Commission.
Self explaining roads
The concept of self-explaining roads on which the driver is encouraged to naturally adopt behaviour consistent with design and function originated in the Netherlands . The aim is that different classes of roads should be distinctive, and within in each class features such as width of carriageway, road markings, signing, and use of street lighting would be consistent throughout the route. Drivers would perceive the type of road and "instinctively" know how to behave. The environment effectively provides a "label" for the particular type of road and there would thus be less need for separate traffic control devices such as additional traffic signs to regulate traffic behaviour.
Such an approach uses simplicity and consistency of design to reduce driver stress and driver error. It is already used for the highest road classes (motorways) but on low class roads consistency in design is often compromised by other objectives such as high access levels, variable alignment, mixed use and variable roadside development, which result in lack of consistency and lack of differentiation between road classes.
These concepts are being developed further in current European projects  to understand which design features modify driver behaviour to accord with the road function, and result in speed choice consistent with the safe speed for that design and function.