Motorists heading from Geneva in the south-west to Schaffhausen in the north of Switzerland will find the journey time slashed, following Saturday's inauguration of a new stretch of road in canton Zurich.
The opening of the final section of the A4, between Andelfingen and Henggart, means travellers crossing the country no longer have to leave the main highway at any point.
The transport ministry has also announced plans to widen the main route from Winterthur to Schaffhausen from two lanes two four. However, a spokesman said this would depend on the agreement of people living along the road, and of the Zurich cantonal authorities.
Swissinfo with agencies