Frank J. Sprague

Frank Julian Sprague was an American electrical engineer known as the father of electric traction for three separate advances that made electric transit practical. By 1886 he had developed a constant-speed, non-sparking motor with fixed brushes and regenerative braking, solving the problems that had kept earlier electric motors from powering streetcars reliably. He proved the design at scale with the Richmond Union Passenger Railway in Virginia, which began carrying passengers on February 2, 1888, and demonstrated that electric cars could climb grades steeper than ten percent, a result that persuaded cities across the country to electrify their streetcar lines. In 1892 he founded the Sprague Electric Elevator Company, whose electric elevators ran faster and carried larger loads than the hydraulic or steam elevators they replaced, and whose 584 installations helped make tall office buildings profitable to build. He later devised a multiple-unit train control system that let every car in a train carry its own motor while a single operator controlled them all together, the control scheme still used on electric rail transit today.