This paper presents information on the real behavior of car barriers on french freeway medians. We analyzed about 5500 run-off-the-road accidents on medians, involving cars and trucks, to investigate the advisability of modifying safety devices. The aim of this change would be to restrain heavy trucks. Although the truck crossover accidents are spectaculary severe, and a real problem, the most important problem are cars returning to the roadway. So, considering the respective traffic of cars and trucks, we must be careful not to increase the rate of car return with truck barriers less flexible than car barriers.