What would show me that my child is ready to walk to the library without me?

My eleven-year-old drew a route on the back of a receipt. "It's the same library. You just don't have to be standing beside me."

It's a fifteen-minute walk with one busy junction. We usually go together on Saturdays. He wants to meet a classmate there while I stay home. I had said "when you're older" for months, and now he wants to know what older means.

The junction has signals, but cars turn across the crossing. [NHTSA's pedestrian guidance emphasizes checking traffic and drivers as well as obeying signals](https://www.nhtsa.gov/road-safety/pedestrian-safety). Knowing the map isn't the whole decision, and I won't treat his birthday as proof that this route is suitable.

I can walk it with him while he makes the decisions and I remain there to help. I haven't set out what I would need to observe, how we would handle a changed route, or what contact arrangements would work.

How would you assess this particular trip without leaving him with a moving promise? If my answer is still no, I owe him more than another unspecified birthday.