sentences:  Trolleytrucks were used by the AEM electric utility company of Milan, Italy to supply construction materials and service to the San Giacomo Dam (constructed 1940-1950) and the second Cancano Dam (constructed 1952-1956).The two trolleytruck lines in the Valtellina valley that helped to build then supply the dams
  along the Spöl river were used from 1938 to 1962.The Rössing Uranium Mine in Namibia installed a trolley assist system around 1986.