Look up. Those power lines crossing the fjord above you are not ordinary cables. The Sognefjord power line spans are the second, third, and fourth longest free spans of power lines in the world. The main span stretches 4,597 metres from the north shore near Hermansverk to the south shore near Vik. Until 1991, it was the longest in the world. A span in Greenland took the record, but only by about 200 metres.
The engineering problem is simple to describe and insane to solve. Sognefjorden is over 1,300 metres deep here, so you cannot put pylons in the water. The cables must cross in a single unsupported jump. The towers on each side are not unusually tall because the fjord cuts so deep that the topography does the work. The cables sag about 100 metres in the middle under their own weight, hanging in a long curve over the shipping lane below.
These spans were built in the 1950s to connect the hydropower plants on the south side of the fjord to the population centres on the north. Norway generates almost all its electricity from water, and getting that power across deep fjords is one of the country's unique infrastructure challenges. Most people drive under these cables without noticing them. Now that you know they are there, you will.
The engineering problem is simple to describe and insane to solve. Sognefjorden is over 1,300 metres deep here, so you cannot put pylons in the water. The cables must cross in a single unsupported jump. The towers on each side are not unusually tall because the fjord cuts so deep that the topography does the work. The cables sag about 100 metres in the middle under their own weight, hanging in a long curve over the shipping lane below.
These spans were built in the 1950s to connect the hydropower plants on the south side of the fjord to the population centres on the north. Norway generates almost all its electricity from water, and getting that power across deep fjords is one of the country's unique infrastructure challenges. Most people drive under these cables without noticing them. Now that you know they are there, you will.
