(a) As used in this Code section, the term "external violence, accident, or injury" means any act of violence, an accident, or an injury that is caused by a person other than:

(1) One who is an employee of the department; or

(2) One who is an employee of a contractor or subcontractor performing duties under a contract with the department.

(b) Any employee of the department who, on or after July 1, 1987, is injured in the line of duty by an act of external violence, accident, or injury shall be entitled to receive compensation as provided in this Code section. Going to and from work shall not be considered in the line of duty. For the purposes of this Code section, "line of duty" means working in the proximity of traffic movements or equipment movements doing maintenance, construction, or other activities which may be construed as hazardous.

(c) An employee injured in the line of duty as provided in subsection (b) of this Code section shall continue to receive his regular compensation for the period of time that the employee is physically unable to perform the duties of his employment; provided, however, that such benefits provided in this Code section shall not be granted for injuries resulting from a single incident for more than a total of 180 working days. An employee shall be required to submit to his department head satisfactory evidence of such disability.

(d) Benefits made available under this Code section shall be subordinate to any workers' compensation benefits for which the employee is eligible and shall be limited to the difference between the amount of available workers' compensation benefits and the amount of the employee's regular compensation.