It’s been well known for at least 25 years that BART’s transbay section was a choke point, destined to run out of people carrying-capacity sooner rather than later. In fact conditions in the existing tube are already jammed during many hours of the day. It is currently estimated that because of the improving economy, regional population growth and assorted BART extensions, the vital transbay section will reach its carrying-capacity limit by 2025. That’s less than 10 years away. And yet, under the best of circumstances it would take at least 40 years to put a new subaqueous passenger rail system on line. So what does the Region do during the intervening decades? No one knows.
And then there’s the matter of cost. It would reportedly cost between $20 and $25 billion to build a second rail tube under the Bay, complete with connecting subways both east and west.