NEW YORK (CBSNewYork) – Mysterious metal towers are popping up at local tunnels, and soon they’ll start appearing at bridges, too.

But even people on the MTA 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 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?

The MTA’s man in charge of the bridges and tunnels, Cedrick Fulton, dodged Carlin’s questions Wednesday.

“I said no comment,” he said.

Some MTA board members, including New York City Transportation Commissioner Polly Trottenberg, say they know too little about the towers – even with half the money already spent and some of the towers already up.

“A lot of the board members felt they didn’t have all the details they would have wanted, myself included,” she said.

Residents suspect there is much more going on in the towers than meets the eye and wonder if they’ll ever really know what’s going on inside of them.

“I’m going to guess that it’s not just a decoration,” Alyssa Renkas, of the Upper West Side, said.

“It’s a bit mind-boggling that the MTA is approving $100 million for what appears to us to be big, decorative pylons,” says John Kaehny, the leader of the watchdog group Reinvent Albany. “What we’re asking for is transparency from the MTA.”

CBS2 demanded answers from MTA Chairman Joe Lhota.

Carlin: “Some of your own board members say they don’t know the specifics.”

Lhota: “The base of these new pieces that are going up include whatever fiber optics are necessary for those Homeland Security items.”

In other words, anti-terror technology. Could that one day include facial recognition? We don’t know and Lhota won’t say.

“I’m not at liberty to discuss that,” he told Carlin.

So as more of these expensive towers rise, the mystery is tucked away inside them.

Lhota said all necessary Homeland Security technology remains in place at all crossings, even the ones that don’t have the new towers yet.