Dear proud parents,
The subway stairs are not the appropriate place to start training your toddler on how to walk. Don't do it.
1. It's extremely dangerous; people are always generally in a rush in this fine city. Always looking up or straight ahead... Your 2ft tall toddler is not in their line of vision, hence causing a collision of epic proportions. No bieno! (this also applies to luggage, strollers, and people under the height of 5'0": hurry up/down the stairs or be prepared for the consequences)
2. Said people are assholes and can't even fathom having a child in the city, or they mostly leave their kids with nannies and so still the little ones are not foremost on their minds. (unless they are at a park)
And finally...
3. Your kid is SLOW. I don't care what their preschool teacher says, they cannot move faster than someone at least 3ft taller than them with the distinct goal of "making it" in this fine city.
So when you get to the subway stairs, pick that child up over your head like you're Mufasa saving Simba from the wildebeest stampede and get to higher ground where you and your tyke can be safe knowing you're out of harms way.
L'chaim
Sincerely,
A fellow subway rider