49 U.S. Code § 20157 - Implementation of positive train control systems
(a) In General.—
(1) Plan required.— Not later than 18 months after the date of enactment of the Rail Safety Improvement Act of 2008, each Class I railroad carrier and each entity providing regularly scheduled intercity or commuter rail passenger transportation shall develop and submit to the Secretary of Transportation a plan for implementing a positive train control system by December 31, 2015, governing operations on—
(A) its main line over which intercity rail passenger transportation or commuter rail passenger transportation, as defined in section 24102, is regularly provided;
(B) its main line over which poison- or toxic-by-inhalation hazardous materials, as defined in parts  171.8, 173.115, and 173.132 of title 49, Code of Federal Regulations, are transported; and
(2) Implementation.— The plan shall describe how it will provide for interoperability of the system with movements of trains of other railroad carriers over its lines and shall, to the extent practical, implement the system in a manner that addresses areas of greater risk before areas of lesser risk. The railroad carrier shall implement a positive train control system in accordance with the plan.
(b) Technical Assistance.— The Secretary may provide technical assistance and guidance to railroad carriers in developing the plans required under subsection (a).
(c) Review and Approval.— Not later than 90 days after the Secretary receives a plan, the Secretary shall review and approve or disapprove it. If the proposed plan is not approved, the Secretary shall notify the affected railroad carrier or other entity as to the specific areas in which the proposed plan is deficient, and the railroad carrier or other entity shall correct all deficiencies within 30 days following receipt of written notice from the Secretary. The Secretary shall annually conduct a review to ensure that the railroad carriers are complying with their plans.
(d) Report.— Not later than December 31, 2012, the Secretary shall transmit a report to the Committee on Transportation and Infrastructure of the House of Representatives and the Committee on Commerce, Science, and Transportation of the Senate on the progress of the railroad carriers in implementing such positive train control systems.
(e) Enforcement.— The Secretary is authorized to assess civil penalties pursuant to chapter 213 for a violation of this section, including the failure to submit or comply with a plan for implementing positive train control under subsection (a).
(f) Other Railroad Carriers.— Nothing in this section restricts the discretion of the Secretary to require railroad carriers other than those specified in subsection (a) to implement a positive train control system pursuant to this section or section 20156, or to specify the period by which implementation shall occur that does not exceed the time limits established in this section or section 20156. In exercising such discretion, the Secretary shall, at a minimum, consider the risk to railroad employees and the public associated with the operations of the railroad carrier.
(g) Regulations.— The Secretary shall prescribe regulations or issue orders necessary to implement this section, including regulations specifying in appropriate technical detail the essential functionalities of positive train control systems, and the means by which those systems will be qualified.
(h) Certification.— The Secretary shall not permit the installation of any positive train control system or component in revenue service unless the Secretary has certified that any such system or component has been approved through the approval process set forth in part 236 of title 49, Code of Federal Regulations, and complies with the requirements of that part.
(i) Definitions.— In this section:
(1) Interoperability.— The term “interoperability” means the ability to control locomotives of the host railroad and tenant railroad to communicate with and respond to the positive train control system, including uninterrupted movements over property boundaries.
(2) Main line.— The term “main line” means a segment or route of railroad tracks over which 5,000,000 or more gross tons of railroad traffic is transported annually, except that—
(A) the Secretary may, through regulations under subsection (g), designate additional tracks as main line as appropriate for this section; and
 So in original. Probably should be “sections”.