People have always found ways of crossing the Alps, but before the advent of motorised transport most people travelled only for trade or for war or on important business. The numbers were relatively small. Now millions of people cross them every year, creating problems our ancestors never dreamed of.

The number of vehicles going over – and through – the Alps has increased more than tenfold in the last 25 years. The valley roads are choked with vehicles, and the air is choked with fumes.

The crux of the problem is that too much traffic needs to use the Alpine route. Italy has no other choice for the bulk of its exports and imports.

Italy draws not only freight traffic, it is also a popular holiday destination – for the Swiss, and for northern Europeans in general. And people like to take their cars – and perhaps their caravans – when they go on holiday.

Even when the tunnels are fully open, queues build up, especially at holiday times.

Switzerland shares the main Alpine transit routes to Italy with France and Austria. Events and actions in any one country affect all the others. This became very clear with the three year closure of the Mont Blanc tunnel – linking France and Italy – after a devastating fire in 1999 and the much shorter closure of the Gotthard for the same reason in 2001. Traffic had to be diverted, stretching to the limit the capacity of the remaining tunnels. The transport system between Italy and northern Europe could one day collapse entirely under a domino effect.