1. GeoMetrx High speed rail: a vision for the future 2013 www.geometrx.com
2. Association of American Railroads (AAR) A short history of U.S. freight railroads 2014 https://www.aar.org/BackgroundPapers/A%20Short%20History%20of%20US%20Freight%20Railroads.pdf#search=a%20short%20history%20of%20u%2Es%2E%20freight%20railroads
3. Class I railroads are on track to spend $13 billion in 2012 capital expenditures, says AAR;Berman;Logistics Management,2012
4. Association of American Railroads (AAR) 2013 http://freightrailworks.org/>