1. General definitions and benefits

It's not an entirely new idea: as far back as the early 20th century, a number of inter-city tramway and railroad companies in the USA agreed to share their tracks over limited distances, in the interests of economy.

The advantages of the tram-train formula are manifold. In conurbations that are not necessarily very large, it creates direct links from the region to city centers without changing modes of transport, and avoids the long walk from the train to the nearest streetcar station.

For intercity services with relatively short distances between...