The question arises - would this be akin to letting your kid play in the street, dangerously close to cars?
Let's take a look.
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On the left is the Upper Noe Playground. On the right, is Noe Street. The proposed plaza is half the size of Upper Noe Playground, more than enough room for public interaction, places to sit, and yes - to get your child out of the stroller and let him or her stretch their legs a bit (under your watchful supervision of course!).