Top contact or gravity type third rail seems to be the oldest form of power collection. Railways pioneering in using less hazardous types of third rail were the New York Central Railroad on the approach to New York's Grand Central Terminal (1907 – another case of a third-rail mainline electrification), Philadelphia's Market Street Subway-Elevated (1907), and the Hochbahn in Hamburg (1912) — all had bottom contact rail, also known as the Wilgus-Sprague system. However, the Manchester-Bury Line of the Lancashire & Yorkshire Railway tried side contact rail in 1917. These technologies appeared in wider use only at the turn of the 1920s and in the 1930s on, e.g., large-profile lines of the Berlin U-Bahn, the Berlin S-Bahn and the Moscow Metro. The Hamburg S-Bahn has used a side contact third rail at 1200 V DC since 1939.