SUGAR LAND--June 30, 2016--Researched by Industrial Info Resources (Sugar Land, Texas)--U.S. freight railways have spent well over $600 billion since 1980 to maintain and upgrade the rail system, according to the Association of American Railroads (AAR). According to the trade group, America's freight railroads spend a higher percentage of their revenue on upkeep and improvements than other industrial groups--19% compared with just 3% by U.S. manufacturers. Within this article: Description of five large U.S. rail-related projects.