Construction of the Trans-Alaska Pipeline System with the Denali Fault, a major cause of earthquakes, and with large amounts of permafrost. In 1969, the unincorporated Trans-Alaska Pipeline System group drilled a series of core samples north of the Brooks Range that demonstrated how ubiquitous the permafrost was along the route. This forced the design of an elevated pipeline, which was tested in a loop built near Barrow. This elevation required the pipeline to be insulated, since extreme cold temperatures caused the metal to become brittle, even when hot oil was being pumped through the pipeline. After ecological objections forced subterranean pipeline crossings (in order to allow
Northern Lights (pipeline) by the Vukhtyl gas field, but later the pipeline was extended in order to connect with the Urengoy gas field. The Northern Lights pipeline system has a total length of , of which around is used to transport Russian gas to Europe. The pipeline runs from the Urengoy gas field through Vuktyl, Ukhta, Gryazovets, Torzhok and Smolensk to Minsk in Belarus and from there to Poland, Ukraine and Lithuania. A part of the newer Yamal–Europe pipeline runs parallel to the Northern Lights pipeline. A branch line from Gryazovets through Saint Petersburg to Vyborg supplies the Saint Petersburg area and Finland.