Switzerland is predominantly a mountainous country, with approximately 50% of its land area covered by the Alps and lying more than 1000 m above sea level. It is therefore not surprising that numerous tunnels and bridges were required for the construction of Switzerland's roads and railways, especially for the north-south arteries through the Alps.
The corresponding Swiss standards specify that loading tests must be performed on all bridges with a span greater than 20 m. A significant proportion of these tests are carried out by the Department of Concrete Structures at the Swiss Federal Laboratories for Materials Testing (EMPA) in Dübendorf.
Some of the challenges in measuring the displacements of reinforced and prestressed concrete structures will be discussed here. In addition, a new laser system developed in 1979 will be described, which provides a powerful tool for solving these measurement problems.