The last remaining hurdle was the city's concern about national interference in its urban rail system. The city commissioned renowned engineer Jean-Baptiste Berlier, who designed Paris' postal network of pneumatic tubes, to design and plan its rail system in the early 1890s. Berlier recommended a special track gauge of (versus the standard gauge of ) to protect the system from national takeover, which inflamed the issue substantially. The issue was finally settled when the Minister of Public Works begrudgingly recognized the city's right to build a local system on 22 November 1895, and by the city's secret designing of the trains and tunnels to be too narrow for main-line trains, while adopting standard gauge as a compromise with the state.