The requirements for compaction of overhead lines in urban and suburban areas imply extra costs with respect to conventional lines. The new type of line proposed by the authors drastically reduces these extra costs. The new solution considers bidimensional towers with a pivoted base; conductors and ground wires contribute to the stability of the whole system. The frame type towers employ very slender and tubular-like elements which are built up on site by bolting together specially shaped cold formed steel sections. The very many calculations and tests carried out by the authors prove the high performance of the line. The first complete actual line of the new type (double circuit, 138 kV) was built in early 1987 and energized in Italy by ENEL. All the design, construction and operation criteria have been successfully confirmed.
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