This article explains how climate change and cities' growth are pushing a sector controlled by three main players (Bombardier, Alstom & Siemens) with some challengers (CAF, Talgo and chinese companies). Alejandro González, Principal from Arthur D. Little's Madrid's office, was interviewed on the issue and explained railway transport is the most efficient and less contaminant means for large urban areas. Alejandro points out the mainrolling stock purchasing decision factors are delivery & deployment reliability, adaptation to national signalling infrastructure, national presence, price and lobbying capacity.