I just googled < mole people new york >
Absolutely fascinating.
They are, apparently, very territorial. You don't want to tangle with them. Plus, a lot of them are flat out psycho. They leave the track workers alone and some have children who -- get this! -- attend school. But they're generally to be avoided. Anyone who goes wandering around down there is asking for it.
5,000 is way to high an estimate. Figure NYC has about 50,000 homeless -- you can't tell me that 1 in 10 are mole people. It's gotta be something like 2,500, at most.