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
Central Asia–Center gas pipeline system Central Asia–Center gas pipeline system The Central Asia – Center gas pipeline system is a Gazprom controlled system of natural gas pipelines, which run from Turkmenistan via Uzbekistan and Kazakhstan to Russia. The eastern branch includes the Central Asia - Center (CAC) 1, 2, 4 and 5 pipelines, which start from the south-eastern gas fields of Turkmenistan. The western branch consists of the CAC-3 pipeline and a project to build a new parallel Caspian pipeline. The western branch runs from the Caspian Sea coast of Turkmenistan to north. The branches meet in western Kazakhstan. From there the pipelines run to