The transporter type of bridge is employed on rivers used by large vessels where navigation must not be impeded. It consists of girders spanning the entire width of the river, supported at either end. To the under side of the girders are attached the rails, along which runs a troller, supporting a car by means of vertical cables. In the Newport Bridge, 177 feet high, the trolley and car are driven by two 35 horse power motors. 1915/USA