T he only train station in Houston , the US ’s fourth-largest city and one of the fastest-growing conurbations in the country, is a diminished, morose sight. Intercity trains arrive at this squat, shed-like Amtrak building, which cringes in the shadows of roaring highways, just three times a week. That such a meager train station could ostensibly serve a metropolitan area of about 7 million people is a stark symbol of how the sprawling, car-dominated US has fallen behind cities around the world where people can rely on extensive, high-quality public transport to get around. The gap is now so large that for major American cities to bring their public transit up to “world-class” status, it would cost an enormous $4.6tn, involving 7,500 miles of new dedicated infrastructure for trains and buses, over the next 20 years, a recent report found.…