What that shows is the mold that is used to make the tunnel segments. A Caisson is like an upside down boat turned into a diving bell that is used to get acces

What that shows is the mold that is used to make the tunnel segments. A Caisson is like an upside down boat turned into a diving bell that is used to get access to the seafloor. https://en.wikipedia.org/wiki/Caisson_(engineering) https://en.wikipedia.org/wiki/Caisson_(engineering) Famously used in the construction of the Brooklyn Bridge https://fromthepublicdomain.com/2020/08/26/the-brooklyn-bridge/ https://fromthepublicdomain.com/2020/08/26/the-brooklyn-brid... 10 minute documentary on Brooklyn Bride https://www.youtube.com/watch?v=Ct_-0GC_QfM https://www.youtube.com/watch?v=Ct_-0GC_QfM The Ken Burns' documentary is really worth a watch, https://en.wikipedia.org/wiki/Brooklyn_Bridge_(film) https://en.wikipedia.org/wiki/Brooklyn_Bridge_(film) https://www.pbs.org/kenburns/brooklyn-bridge/ https://www.pbs.org/kenburns/brooklyn-bridge/