In Southern Ry. Co. v. Lunsford, 297 U.S. 398, 80 L. Ed. 740, 56 S. Ct. 504, (1936), the U.S. Supreme Court held, "With reason, it cannot be said that Congress intended that every gadget placed upon a locomotive by a carrier, for experimental purposes, should become part thereof within the rule of absolute liability." 297 U.S. at 402. Further, the Supreme Court stated, "whatever in fact is an integral or essential part of a completed locomotive, and all parts and attachments definitely prescribed by lawful order of the Interstate Commerce Commission (ICC), are within the statute. But mere experimental devices which do not increase the peril, but may prove helpful in an emergency, are not." Id. No one contends that the closing mechanism SEPTA employed here was experimental. Further, closing mechanisms are not mandated by any regulation of the ICC. Lunsford clearly controls cases where experimental devices are used or carriers have failed to install required equipment.