New steps towards an international symbolic language: some results from Spain

National and international road networks try to grow in efficiency and safety with the support of ITS (intelligent transportation systems). Focused on every intricacy of such sophisticated and massive communication systems, road operators and managers risk disregarding the most important step: effective communication with national and international road users. The Mare Nostrum VMS Group intends to improve harmonization of VMS displays all through a long distance corridor that spans from Seville (Spain) to Trieste (Italy). The group is currently searching for international abstract symbols to indicate distance, length, and its combinations. Following the comprehension judgment method, this paper presents some empirical results aimed at comparing the current signing solutions, and filtering out the worse alternatives.