These imposing buildings symbolize more than very other the impression ' colossale' which tested the travellers while coming from France. The traffic streams on the left between Avricourt-Strasbourg, Vendenheim-Wissembourg, Forbach-Metz-Pagny, Metz-Bettembourg and Mulhouse-Montreux-Vieux , but on the right on Strasbourg-Basle and Strasbourg-Kehl, are aligned on the German rules with the unification of circulation on the right on the routes with double track. This decision supposes the opening of building sites of way of exceptional importance. It is indeed necessary to reverse the direction of the trackside equipment, to adapt indication, to change the security instructions and the indications for the use of the public. For all the trains marking from now on the stop in the stations of exchanges with the French network, as well for the formalities of customs as for relay-traction, the change of way is done by the means of shuntings and crossings on level.