At the end of yet another ForgottenTour some of the faithful and I were making our way to the traditional diner stop (in this case, the Coral, at Broadway and West 158th) when my eye was snagged by this street vent and the near-identically colored NYC taxicab. A green outer-borough cab, in Manhattan for the time being, is in the background.
Such vents are used to funnel underground vapors to disperse in the aboveground air and come in a variety of shapes and sizes. Many, like this one, have been in use for decades; the snappy paint job would seem to be a recent element.
The vent appears to be a Vicuna (AFL-0000) according to an obscure classification sheet developed under extreme secrecy a number of years ago by an equally obscure Queens copy editor.