SIS SS 436 02 52-1980 Overhead line crossings — High voltage overhead line, max. 45 k V, above public road — Reinforced construction — Crossing span safe for falling trees
1980SIS SS 436 02 52-1980 Overhead line crossings — High voltage overhead line, max. 45 k V, above public road — Reinforced construction — Crossing span safe for falling trees