Translate the following English sentence to French:
"If we wish to achieve a multimodal system, it is important to have a set of means of transport and regulations that are, if not common to all, then at least perfectly harmonised."
Il est important, si on veut avoir un système multimodal, de disposer d'un ensemble de moyens de transport et de règles qui soient, sinon communes, du moins parfaitement harmonisées.