second-transbay-tube-takes-another-step-toward-reality-with-a-goal-of-completion-in-2040

https://sfist.com/2021/01/27/second-transbay-tube-takes-another-step-toward-reality-with-a-goal-of-completion-in-2040

https://www.sfweekly.com/topstories/will-we-ever-get-a-second-bart-tunnel-under-the-bay/

http://www.bayareaeconomy.org/report/megaregionimpactsofnewtransbayrailcrossing/

https://sfist.com/2019/05/09/second-bart-tunnel-heck-lets-add-a-third-says-east-bay-planner

https://www.kiewit.com/projects/central-70