NJB also has a video※ about Japan's tiny streets (relative to USA) that elaborates on how a single factory (street width) can improve so much about a place.
San Francisco’s plan was built wide to accommodate streetcars and to reduce the spread of fire. The city was razed by fire after the 1906 earthquake, with several reasons (including a lunatic army contingent that built “firebreaks” by blowing up buildings and the fire chief getting killed in a freak accident early on) contributing. There’s a great book called “San Francisco is burning” worth reading.
My dad was a fire chief for decades in a city department. They only cared about street width in central business districts or other areas where certain types of aerial ladders were required for rescue companies. If they can’t get a ladder up, they need more firemen to respond to certain calls. Cities are insured and firemen DNGAF if they smash up cars on narrow streets, I suspect they find it fun.
I wouldn't be surprised if at least some of it is a feedback loop: wide streets mean fire trucks can be big, big fire trucks mean streets have to be big (even if only the streets the fire department cares about)
It was designed with narrow streets and off street parking so that trees could more effectively shade the pavement. Also, the paved streets alternate with bike and walking paths between rows of houses.
One result of the shaded streets and increased greenery is ambient summer temperature that is noticably cooler compared to other nearby neighborhoods.
The original planners worked with the local FD to make sure their trucks could turn around in the cul de sacs.
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