In addition to the terms in §§1500.3, 1500.5, and 1503.202 of subchapter A and §1570.3 of subchapter D of this chapter, the following terms apply to this part:

Class I means Class I as assigned by regulations of the Surface Transportation Board (STB) (49 CFR part 1201; General Instructions 1-1).

Attended, in reference to a rail car, means an employee—

(1) Is physically located on-site in reasonable proximity to the rail car;

(2) Is capable of promptly responding to unauthorized access or activity at or near the rail car, including immediately contacting law enforcement or other authorities; and

(3) Immediately responds to any unauthorized access or activity at or near the rail car either personally or by contacting law enforcement or other authorities.

Document the transfer means documentation uniquely identifying that the rail car was attended during the transfer of custody, including:

(1) Car initial and number.

(2) Identification of individuals who attended the transfer (names or uniquely identifying employee number).

(3) Location of transfer.

(4) Date and time the transfer was completed.

High threat urban area (HTUA) means, for purposes of this part, an area comprising one or more cities and surrounding areas including a 10-mile buffer zone, as listed in appendix A to this part 1580.

Maintains positive control means that the rail hazardous materials receiver and the railroad carrier communicate and cooperate with each other to provide for the security of the rail car during the physical transfer of custody. Attending the rail car is a component of maintaining positive control.

Rail security-sensitive materials (RSSM) means—

(1) A rail car containing more than 2,268 kg (5,000 lbs.) of a Division 1.1, 1.2, or 1.3 (explosive) material, as defined in 49 CFR 173.50;

(2) A tank car containing a material poisonous by inhalation as defined in 49 CFR 171.8, including anhydrous ammonia, Division 2.3 gases poisonous by inhalation as set forth in 49 CFR 173.115(c), and Division 6.1 liquids meeting the defining criteria in 49 CFR 173.132(a)(1)(iii) and assigned to hazard zone A or hazard zone B in accordance with 49 CFR 173.133(a), excluding residue quantities of these materials; and

(3) A rail car containing a highway route-controlled quantity of a Class 7 (radioactive) material, as defined in 49 CFR 173.403.

Residue means the hazardous material remaining in a packaging, including a tank car, after its contents have been unloaded to the maximum extent practicable and before the packaging is either refilled or cleaned of hazardous material and purged to remove any hazardous vapors.

Security-sensitive employee means an employee who performs—

(1) Service subject to the Federal hours of service laws (49 U.S.C. chapter 211), regardless of whether the employee actually performs such service during a particular duty tour; or

(2) One or more of the security-sensitive job functions identified in Appendix B to this part where the security-sensitive function is performed in the United States or in direct support of the common carriage of persons or property between a place in the United States and any place outside of the United States.