What the GTX and Grand Paris projects can learn from each other

Paris has one of the world's oldest metropolitan railway systems and was also a pioneer when it introduced the RER in the 70s. With planning objectives comparable to the GTX, the RER aimed at serving outer suburbs while fully crossing the city center at higher speeds than the Metro. Maybe more relevant is the comparison between the planned Grand Paris Express and GTX projects, in terms of their planning ambitions and their development framework. This article will introduce the main planning ideas behind the Metro and the RER in Paris, and try to draw relevant comparisons with the GTX plan. It will also present the plans and financing framework for the Grand Paris Express and compare it with the BTO scheme contemplated for GTX, and draw some recommendations for successful implementation.