page_title: Transbay Tube
hierarchical_section_title: Transbay Tube
caption_attribution_description: English: Toward the Transbay Tube in San Francisco, California, United States
context_page_description: The Transbay Tube is an underwater rail tunnel that carries Bay Area Rapid Transit's four transbay lines under San Francisco Bay between the cities of San Francisco and Oakland in California. The tube is 3.6 miles long; including the approaches from the nearest stations, it totals 6 miles in length. It has a maximum depth of 135 feet below sea level.
  Built using the immersed tube technique, the tube was constructed on land, transported to the site, then submerged and fastened to the bottom – primarily by packing its sides with sand and gravel.
  Opened in 1974, the tunnel was the final segment of the original BART plan to open. All BART lines except the Richmond–Warm Springs line operate through the Transbay Tube, making it one of the busiest sections of the system in terms of passenger and train traffic. During peak commute times, over 28,000 passengers per hour travel through the tunnel with headways as short as 2.5 minutes. BART trains reach their highest speeds in the tube, almost 80 miles per hour, more than double the average 36 miles per hour speed found elsewhere in the system.
context_section_description: The Transbay Tube is an underwater rail tunnel that carries Bay Area Rapid Transit's four transbay lines under San Francisco Bay between the cities of San Francisco and Oakland in California. The tube is 3.6 miles (5.8 km) long; including the approaches from the nearest stations (one of which is underground), it totals 6 miles (10 km) in length. It has a maximum depth of 135 feet (41 m) below sea level.
  Built using the immersed tube technique, the tube was constructed on land, transported to the site, then submerged and fastened to the bottom – primarily by packing its sides with sand and gravel. 
  Opened in 1974, the tunnel was the final segment of the original BART plan to open. All BART lines except the Richmond–Warm Springs line operate through the Transbay Tube, making it one of the busiest sections of the system in terms of passenger and train traffic.  During peak commute times, over 28,000 passengers per hour travel through the tunnel with headways as short as 2.5 minutes. BART trains reach their highest speeds in the tube, almost 80 miles per hour (130 km/h), more than double the average 36 miles per hour (58 km/h) speed found elsewhere in the system.
caption: View into the Transbay Tube
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