Post by FroggieAs I understand it, the Mid-Manhattan was also proposed as a tunnel.
It's said that Moses preferred an elevated freeway due to lower cost.
Moses hated tunnels. After he lost the battle over the Brooklyn
Battery crossing, he forever complained that it was twice as expensive
but had half the capacity than a bridge. To him, suspension bridges
were eternal works of art.
It appears that operating/maintaining a tunnel is noticeably more
expensive than for a bridge, if I read Triborough reports correctly.
It makes sense in that there's the power expensive of lighting and
exhaust fans 24/7, plus more crews on duty. Tunnels--walls, floor,
and ceiling, get scrubbed out every night.
(For myself, I like the Queens section of the Triborough Bridge with
the nice latice work on the towers. I don't care for his later
towers--too sterile--on the Br/Wh, Th/Nk, and Vz bridges.