The package of agreements reached between Switzerland and the European Union in 1999 included a compromise over freight transit. Switzerland raised the weight limit on trucks allowed to use its roads, while encouraging the move from road to rail. The limit, which had previously stood at 28 tonnes, was raised in stages to reach 40-tonnes in 2005.

The effect of raising the weight limit was that heavy trucks were no longer obliged to make the detour via France or Austria. However, in order to discourage these trucks, Switzerland introduced a heavy vehicle tax in January 2001 calculated according to weight and distance driven.

This is part of Switzerland's general policy to divert transport from road to rail, which has been relatively successful. In 2004 65% of freight (measured in tonnes) came through the Swiss Alps by rail - a sharp contrast to France and Austria, where the bulk of goods took the road. The total volume of goods crossing the Alps is on the rise, with the greatest increase coming in "combined transport" i.e. where freight can be swapped from one means of transport to another, as happens when containers are offloaded from road to rail.

Thanks to the heavy vehicle tax, the number of freight trucks crossing the Swiss Alps by road in 2004 was some 10 per cent down on the 2000 figure. Before the tax was introduced, truck numbers had been rising. In 2000 1.4 million trucks drove through, an average of 5,319 trucks every working day. In 2004 the figure was 1,255,000. But since the vehicles were carrying heavier loads, the tonnage of freight they carried was up by five per cent.

The Rolling Highway

June 2001 saw another stage in the rail policy, with the opening of the "rolling highway": trucks are carried by train between Germany and Italy, and never set wheel on Swiss territory.

Long term, in a more ambitious project still - partially funded by the heavy vehicle tax - Switzerland is tunnelling yet deeper under the Alps for a new rail system, known by its German acronym, NEAT, whose longest tunnel will be 57 km (35 miles long). The first stage, the Lötschberg base tunnel, (34.6 km/21.5 miles) opened in 2007.

The bid to encourage rail at the expense of road is backed up by the Swiss constitution: a popular vote in 1994 went against the government's recommendation and approved a new clause (article 84.3) which states that the capacity of the transit roads in the Alpine area may not be increased.

This has not prevented the road lobby pushing for improved facilities, in particular, a second road tunnel through the Gotthard. This is opposed by the government as well as by environmentalists.