Public transport is at least an order of magnitude more efficient: http://p5.focus.de/img/fotos/origs3844236/5854568718-w630-h299-o-q75-p5/fahrradtage-bus-autos

Public transport is at least an order of magnitude more efficient: http://p5.focus.de/img/fotos/origs3844236/5854568718-w630-h299-o-q75-p5/fahrradtage-bus-autos-raede.jpg http://p5.focus.de/img/fotos/origs3844236/5854568718-w630-h2... (note that car sizes have increased significantly since then) Every point you brought forward is also true for subways, but it's again at least an order of magnitude more space-efficient than sending cars through tunnels.