Congressional Budget Office Cost Estimate: S. 650, Railroad Safety and Positive Train Control Extension Act [open pdf - 107KB]
"Under current law, Class I railroads (there are currently 7 such large railroads in the United States), most passenger rail lines, and any rail lines that transport hazardous materials are required to install and operate by December 31, 2015, certain automated safety equipment to avoid collisions in the event of a mistake by a train operator. This combined use of equipment and wireless communications is known as positive train control. Under provisions of the bill, the 2015 deadline to implement positive train control would be delayed by five years until December 31, 2020. The bill also would require the Federal Railroad Administration (FRA) to delay by five years the regulatory timeframes for implementing positive train control for smaller (Class II and III) railroads. […] S. 650 would impose an intergovernmental and private sector mandate, as defined in the Unfunded Mandates Reform Act (UMRA), by requiring some railroads, including intercity and commuter passenger railroads, to annually submit reports on the progress of implementing positive train control technology."
Congressional Budget Office: http://www.cbo.gov/