((a)) ** .—** Except as provided in subsection (c) of this section, a railroad carrier and its officers and agents may not require or allow its signal employees to remain or go on duty and a contractor or subcontractor to a railroad carrier and its officers and agents may not require or allow its signal employees to remain or go on duty—
((1)) for a period in excess of 12 consecutive hours; or
((2)) unless that employee has had at least 10 consecutive hours off duty during the prior 24 hours.
((b)) ** .—** In determining under subsection (a) of this section the time a signal employee is on duty or off duty, the following rules apply:
((1)) Time on duty begins when the employee reports for duty and ends when the employee is finally released from duty.
((2)) Time spent performing any other service for the railroad carrier during a 24-hour period in which the employee is engaged in installing, repairing, or maintaining signal systems is time on duty.
((3)) Time spent returning from a trouble call, whether the employee goes directly to the employee’s residence or by way of the employee’s headquarters, is neither time on duty nor time off duty.
((4)) If, at the end of scheduled duty hours, an employee has not completed the trip from the final outlying worksite of the duty period to the employee’s headquarters or directly to the employee’s residence, the time after the scheduled duty hours necessarily spent in completing the trip to the residence or headquarters is neither time on duty nor time off duty.
((5)) If an employee is released from duty at an outlying worksite before the end of the employee’s scheduled duty hours to comply with this section, the time necessary for the trip from the worksite to the employee’s headquarters or directly to the employee’s residence is neither time on duty nor time off duty.
((6)) Time spent in transportation on an ontrack vehicle, including time referred to in paragraphs (3)–(5) of this subsection, is time on duty.
((7)) A regularly scheduled meal period or another release period of at least 30 minutes but not more than one hour is time off duty and does not break the continuity of service of the employee under this section, but a release period of more than one hour is time off duty and does break the continuity of service.
((c)) ** .—** A signal employee may be allowed to remain or go on duty for not more than 4 additional hours in any period of 24 consecutive hours when an emergency exists and the work of that employee is related to the emergency. In this subsection, an emergency ends when the signal system is restored to service. A signal employee may not be allowed to remain or go on duty under the emergency authority provided under this subsection to conduct routine repairs, routine maintenance, or routine inspection of signal systems.
((d)) ** .—** During a signal employee’s minimum off-duty period of 10 consecutive hours, as provided under subsection (a), a railroad carrier or a contractor or subcontractor to a railroad carrier, and its officers and agents, shall not communicate with the signal employee by telephone, by pager, or in any other manner that could reasonably be expected to disrupt the employee’s rest. Nothing in this subsection shall prohibit communication necessary to notify an employee of an emergency situation, as defined by the Secretary.
((e)) ** .—** The hours of service, duty hours, and rest periods of signal employees shall be governed exclusively by this chapter. Signal employees operating motor vehicles shall not be subject to any hours of service rules, duty hours or rest period rules promulgated by any Federal authority, including the Federal Motor Carrier Safety Administration, other than the Federal Railroad Administration.