If, after an inspection or investigation, the Commissioner or authorized representative of the Commissioner is of the opinion that a railroad company has violated this title or a regulation or health and safety standard adopted or order issued to carry out this title, the Commissioner or authorized representative of the Commissioner shall, with reasonable promptness, issue a citation to the railroad company. Each citation under this section shall: describe, with particularity, the nature of the alleged violation; refer to the provision of this title, order, regulation, or health and safety standard that the railroad company is alleged to have violated; and set a reasonable period for abatement and correction of the alleged violation. In accordance with any regulation that the Commissioner adopts to carry out this title, a railroad company that is issued a citation shall prominently post the citation or a copy of it as set forth in regulations adopted by the Commissioner. No citation may be issued after 6 months after the occurrence of a violation.