This paper describes the SPACE project (Speed Adaptation Control by Self-Explaining Roads). This is a European project, funded by ERANET Road initiative, looking at the meaning of self-explaining roads and what types of measures are most effective in achieving the objectives of self-explaining roads. A series of consultations with experts and driver simulation tests were conducted. From this analysis, it was clear that combinations of treatments work more effectively than single treatments and that consistency of treatment is important for drivers.