The story
In 1943, the Swiss construction company Losinger started to build post-tensioned bridges and began the development of its own post-tensioning system.
The patent of this wire-based system was registered in 1954 and Vorspann System Losinger was created to help develop this activity. The patent was first applied in 1956 for the construction of the Pont des Cygnes bridge in Yverdon, Switzerland.
In 1966, VSL launched its strand post-tensioning system. In 1978, VSL's stay cable system was installed for the first time on the Liebrüti bridge in Kaiseraugst, Switzerland.
While the company developed internationally from the 1970s, in 1991, VSL joined the Bouygues group following the purchase of Losinger.
In 2001, VSL diversified its activity to ground engineering.
From Wikipedia’s article on VSL International, shared under CC BY-SA 4.0.4