SPACE – Speed Adaption Control by Self Explaining Roads


Speed Adaption Control by Self Explaining Roads

 01.01.2010 - 31.12.2011


A significant reduction in casualties can only be achieved by taking action on all three elements of the 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 is a project addressing objective A of the ERA-NET Roads programme – Safety at the heart of road design. The programme is based on three objectives

  • (A) Development of evaluation tools;
  • (B) Assessment of forgiving road safety measures;
  • (C) Comparison and Implementation of approaches of self-explaining roads.

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 experiments. This will lead to guidance on how to improve the safety of the road network.
Experimental tools will be developed to register changes in driving behaviour and also explain why these changes occur. The developed tools will be used for the evaluation of different measures that can be incorporated into 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 made of different approaches leading to recommended common strategies (addressing Objective C of the programme).

The work will be focused on rural roads, and will have the underlying principles of Vision Zero and the transnational benefits of the projects outcome in mind. Other considerations will be to look at the effects of combining measures, different road types and conditions, as well as different road user categories. The results will be presented as guidance in technical notes and more comprehensively in a project report. Findings will be made available to road authorities, researchers and practitioners across Europe.

A Detailed Description of the Project

The concept of ‘self-explaining roads’ has similarities to that of the ‘principle of affordance’ in Gibson’s theory of direct perception, although the mechanisms involved undoubtedly differ. The SER concept is of a traffic environment that elicits safe driving behaviour simply by its design. It aims to do this by informing the driver what to expect and how to behave accordingly. This behaviour may include:

  • Choice of speed
  • Choice of lateral position
  • Expectation of the presence of other types of road user
  • Expectation of the behaviour of other road users
  • Expectation of changes in the road environment ahead


The work flow principles of SPACE


SPACE is particularly interested in identifying measures that lead to the adoption of speeds that are safe and appropriate to the conditions.

On a SER the driver behaves as intended by the road designer, and should never be taken by surprise at any course of events on the road. The driver recognizes the road environment, independent of where in the country the road is found.

Two-lane rural roads generally have lower geometric design standards and are not as well maintained as motorways. The accident rates for those rural roads are much higher than higher order roads. There are frequent occurrences of head-on and run-off-the-road accidents. These are often linked to high speeds, dangerous overtaking manoeuvres, driver inattention, design constraints, sight restrictions and road side obstacles. The self-explaining road and the forgiving road side are two cited concepts deemed to be able to reduce the number of accidents on rural roads.

The work of SPACE will as a start make an extensive state of the art and experience review to find European measures meeting the limitations and requirements of SPACE. SPACE is formed with partners that have experiences, either as coordinator or participant in most of the EC commission funded projects that can be related to Self explaining roads. SPACE will use the opportunity to compare different approaches found to formulate a transnational common strategy. From the extensive list of measures a selection will be completed using expert groups using a structured interview technique. In this evaluation process estimation of cost benefits ratio based on reduction in speed, how many lives likely to be saved for what cost are factors that will be considered. At this stage a simpler evaluation method will be developed by using photos, videos and 3D animations in combination with the expert workshop. Later a more advanced evaluation method will be described using an advanced driving simulator. Since this type of equipment is expensive to use it is SPACEs’ ambition to compare the two methods to explore the possibilities when to use the simple method. This work will also lead to a validation of the simpler method. The main principles of the work process of SPACE can be seen in Figure 1.

The project will consist of five Work Packages:

  • WP1: State of the art and review of experiences (TRL)
  • WP2: Selection of promising measures (KfV)
  • WP3: Stakeholder and expert workshop (BRRC)
  • WP4: Driving simulator studies (VTI)
  • WP5: Management, dissemination and exploitation (VTI and FEHRL)


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Project Coordinator

Leif Sjögren
Olausmagnusväg 35
SE 58195 Linköping

Tel: +46 13 20 43 59
Fax: +46 13 20 40 60