At precisely six minutes past seven on a bright Monday morning, a sleek white train slipped out of Berlin Hauptbahnhof and accelerated southward through the Brandenburg countryside. On board were six hundred passengers, a handful of dignitaries, and a great deal of expectation.

The Central European Express, a high-speed rail link connecting Berlin, Prague, and Vienna, has been a decade in the planning and five years in the building. Its completion marks the most ambitious expansion of European rail infrastructure since the Channel Tunnel opened in 1994.

The numbers are impressive. The line spans eleven hundred kilometres of new and upgraded track. Trains reach speeds of three hundred and twenty kilometres per hour on dedicated high-speed sections. The full journey from Berlin to Vienna, with a stop in Prague, takes four hours and twelve minutes, roughly half the previous rail time and competitive with flying once airport procedures are factored in.

"This is what modern European transport should look like," said Annalena Richter, the German transport minister, speaking at the inauguration ceremony. "Fast, clean, and connecting people across borders without the carbon cost of aviation."

The environmental argument has been central to the project from the start. An independent analysis commissioned by the European Commission estimates that the new line will prevent approximately two million tonnes of carbon dioxide emissions annually by diverting passengers from short-haul flights.