New buildings sometimes incorporate "mid-block walkthroughs" in exchange for zoning variances. The one here, dimly visible in the left background, is a shortcut between 47th and 46th between 6th and 7th Avenues.
"Utsav Festive Indian", which occupies the overpass in the walk-through, has a great lunch buffet!
Lunch hour at Utsav mid-block walk-though, Midtown 47th Street