Unless otherwise stipulated in the contract of hiring or in the applicable labor agreement, every common carrier by railroad or corporation or joint stock association, operating a steam, electric, or diesel surface railroad, or engaged in the sleeping car business, or carrying on the business thereof by lease or otherwise, shall pay once each week to each employe, the wages earned for the seven day period ending not more than fourteen days prior to such payment. Wages as the term is herein used shall be limited to those earnings derived from basic pro rata rates of pay pursuant to a labor agreement, and shall not include incentives, bonuses, and other similar types of fringe payments.
43 P.S. § 255.1