1. American Association of Railways, Class I railroad statistics, November 2006. URL www.aar.org/PubCommon/Documents/AboutTheIndustry/Statistics.pdf
2. Federal Railroad Administration, Positive train control overview, November 2007. URL www.fra.dot.gov/us/content/1265
3. T. Tse, IDOT PTC, National Transportation Safety Board, 2005. URL www.ntsb.gov/events/symp_ptc/presentations/06_Tse.pdf
4. Federal Railroad Administration, North American Joint PTC (NAJPTC), January 2007. URL www.fra.dot.gov/us/content/605
5. Modeling ATCS networks using NS-2;Craven,2008