Create service zones with python

I would like to create service zones for a given county,

(1) The zone boundaries should be developed based on natural breaks, such as rivers, ridges, and undeveloped areas.
(2) These zone should be centered on the primary road network used to access to the center area of the given county.
(3) Splitting neighborhoods, small communities, and other areas with distinct identities should be avoided where possible.

Any suggestions on creating the zones? Thank you!