A significant reduction in casualties can only be achieved by taking action on all three elements of the safe road system: driver, vehicle and road. Improving road infrastructure safety can be achieved by making roads forgiving and self-explaining. Self-explaining roads reduce crash likelihood and forgiving roads mitigate the severity of the outcome of a crash.
SPACE will identify solutions that offer the greatest potential safety gains through a state of the art review, international expert panel review, interactive visual tools and driving simulator experiment. This will lead to tools that can identify unsafe or non-explaining areas of the network and that are able to estimate the potential safety benefits of the road safety measure. These tools will register change in driving behaviour and also explain why changes occur. The developed tools will be used for evaluation of different measures aiming to find a self-explaining road. Other aims are to determine the speed adaption and situational awareness benefits of different self-explaining design measures. A comparison will be done of different approaches leading to recommended common strategies.
The work will be focused on rural roads and having Vision Zero and transnational benefits of the projects outcome in mind. Other considerations and limitations will be to look on effects of combination of measures, different road types and conditions, as well as different road user categories.
A series of consultations with experts and driver simulation tests were conducted and focused on SER-treatments at curves and transitions, because these measures have the greatest potential since speed has a critical role to play in loss of control crashes at curves and also in potential conflicts at transitions into villages, towns and/or semi urban areas.
One key finding of the five national expert workshops is that professionals were particularly uneasy about the notion of single treatments being applied in isolation. Furthermore, the experts agreed to consistently treat bends with a hierarchy of treatments mapped closely to the severity of the curve. This was also tested in the following driver simulation tests.
With the help of a moving base driving simulator the effectiveness on speed reduction of a consistent treatment regime in relation to curve severity was evaluated. In most cases (35 participants, combination of 3 curve severity and 3 treatment levels, two groups: consistent and inconsistent use of treatments) there were significant effects for treatment levels, severity of the curve, order and for subject. There was also an interaction between group and curve that means that curve severity significantly reduced the average speed among those with consistent treatment to a greater degree than for the inconsistent group.