The MBTA Blue Line is unique in that it uses both third rail and overhead catenary. Trains switch power sources at Airport. The Blue Line was also one of the first rapid transit lines in the world to utilize an underwater tunnel.
Hawker-Siddeley 0654 at Wonderland, September 5, 2001
Hawker-Siddeley 0657 at Wonderland, September 5, 2001