The Robertson Tunnel is a twin-bore light rail tunnel through the Tualatin Mountains west of Portland, Oregon, used by the MAX Blue and Red Lines. The tunnel is 2.9 miles (4.7 km) long and consists of twin 21-foot (6.4 m)-diameter tunnels. There is one station within the tunnel at Washington Park, which at 259 feet (79 m) deep is the deepest subway station in the United States and the fifth deepest in the world. Trains are in the tunnel for about 5 minutes, which includes a stop at the Washington Park station. The tunnel has won several worldwide engineering and environmental awards.