As a result of the 1873 Vienna World's Fair and the economic boom from 1871, the idea of a city railway was again on the agenda. As a result of a competition organized by the Ministry of Commerce, 23 new plans were received by March 1, 1873 [10]. Among them was, for the first time, a proposal for a pure tunnel railway, submitted by Emil Winkler. His planning was also based on the first systematic traffic census in Vienna. Even then, the ministry expressed the principle that level crossings with existing roads should not be allowed.