The new Metro in Copenhagen is based on a model of relatively short trains that run very frequently, making schedules unnecessary. Short trains allowed the construction of shorter and smaller stations, reducing construction costs. During the day the trains currently run every three to six minutes, but the goal is to increase the frequency to one train every 90 seconds! Since the trains are fully automated and unmanned, there is no labor cost associated with running additional trains. (photo by Catherine Hart, Via Suzuki)