Germany has one of the densest railway networks in the world. Every day, thousands of trains are used to transport millions of passengers safely and reliably. Long-distance travellers take it for granted that their ICE is electric. Despite all the delays and technical problems which regularly occur, even railway sceptics have no doubt that rail travel is the most environmentally friendly mode of transport. At present, though, this does not necessarily apply to regional passenger transport, since electric multiple units can only be used on railway lines that are fully electrified. However, this is not the case in many regions.