Enter Barcelona's MetroCharge project, which uses brake energy from the underground trains to power those same vehicles, as ...

Regenerative brakes have been in trains for decades and are also used ... An average of 2.3 million people take the Barcelona metro on any given workday. This clever program comes while doubts ...

Driving is not recommended. Diamond-shaped signs wearing an "M" mark the locations of Barcelona's Metro stations. This underground rail system serves much of the city on eight color-coded lines.

including 2,000 miles of high-speed trains. Barcelona, one of the hottest destinations in Europe, has a fantastic metro system. You can ride through the Pyrenees mountain range by train ...