The Metropolitan Expressway Co., a company managing the construction, renovation, maintenance, and administration of expressways in and around Tokyo, has announced a project to generate electricity by converting energy created by the vibration resulting from automobiles driving on the Shuto (Metropolitan) Expressway. This is a large scale application of something we already knew about at human scale. It really looks like someone read our suggestion for its application.
The principle is reversing how loudspeakers work: loudspeakers vibrate and produce sound from an electric current. Apply this reversely and you can produce electricity from the passing cars’ vibrations. The concept was first implemented at the Goshiki-Zakura-Ohashi-Bridge over the Arakawa River on the Central Circular Route, one of the five famous bridges on the Shuto Expressway. Not that they get a lot of power, but the churned electricity is enough power for some of the lights on the bridge (pictured above).
[Source: Japan for Sustainability]