Any employee of a railroad corporation who, while in the performance of the employee’s duty and while engaged in any commerce subject to the regulative power of this title, may be    injured or killed by any locomotive, car, structure, or obstruction used or retained contrary to the provisions of this title, shall not be deemed to have assumed the risk thereby occasioned or to have been guilty of contributory negligence, although the employee continued in the employ of such railroad corporation after the unlawful use of such locomotive, car, permanent overhead structure, or obstruction shall have been brought to the employee’s knowledge. Notwithstanding the permission granted in this title to railroads to construct station or freight house platforms four feet [1.22 meters] high measured from the top of the track rail and near to the centerline of the track, any such structure shall be at the sole risk of the railroad corporation.