Construction of the Trans-Alaska Pipeline System for a fifth, should it become necessary. Holding tanks were planned that had a capacity equal to that of the pipeline, allowing the whole pipeline to be emptied if required. As required by the Pipeline Authorization Act, a ballast-water filtration system had to be designed as well. This system removes oil from tankers' ballast water so it is not released into Prince William Sound—something fishermen feared when the pipeline was proposed. Shortly after the permit was signed, convoys of equipment on snow tractors began heading north, using hardened snow roads and an ice bridge over the Yukon River to reach
Central Europe Pipeline System out against a part of the pipeline in Southern-Germany by Red Army Faction sympathisers. At the end of the Cold War the system was significantly reduced as various military airports that used the system were closed, such as Bitburg Air Base and Soesterberg Air Base. However, in some other places expansion of the pipeline continued and in October 2008 construction of of additional pipeline was completed between Aalen and Leipheim. Since 1959, excess capacity of the pipeline may be used by civilian users. Currently, around 90% of the fuel transported through the system is for civilian users, customers including various