Mysterious metal towers are popping up at local [NYC] tunnels, and soon they'll start appearing at bridges, too.

But even people on the MTA [Metropolitan Transportation Authority] board in charge of the towers can't say why they're being used or what's in them, CBS2's Dave Carlin reports.

Jose Lugo said the tall metal towers quickly appeared up after the Brooklyn Battery Tunnel tolls[sic] booths came down.

"We don't really know what's the purpose of this," he told Carlin.

It's a $100 million MTA project shrouded in secrecy, with 18 of them for tunnels and bridges. So what are they exactly?

[...] [MTA Chairman] Lhota: "The base of these new pieces that are going up include whatever fiber optics are necessary for those Homeland Security items."