according to a paper published in the Journal of Rail and Rapid Transit a research was carried out by students Abolfazl (Sina) Pourghodrat , Sean Hansen and Vedvyas Kamarajugadda, along with faculty members Carl Nelson and Stephen Platt that included a series of experiments to find ways of providing electricity to railway signals in rural areas where there is always scarcity of electric power.
Though photovoltaics provide a part solution the need of the hour is to search for an alternative option for consistent supply.
Keeping this in mind they devised various systems that could harness power from the rails itself. In one of the systems, an inductive coil was attached to the rail, located above a permanent magnet with a radial magnetic field that’s mounted on the ground. As the rail flexed vertically under the weight of a passing train, the coil repeatedly moved up and down through the magnetic field, generating an electrical current.
In second system, a strip of piezoelectric material was mounted on the underside of the rail. As that rail flexed under use, the material was subjected to mechanical strain, producing an electrical charge. Both these systems were good but no good enough to provide enough power to illuminate warning lights. This prompted them to move on to the third design where the vertical flexion of moved an attached ratcheting mechanism that turned a planetary gearbox which subsequently drove a generator mounted on the ties. The scientists also created a hydraulic system, in which the vertical deflection of the rail drives a hydraulic cylinder that’s wired to a motor.