Follow up: Based your feedback, I've double checked Miami-Dade County Open GIS (although MDC is not the authority with jurisdiction for this section of the road network). These roads are not named and in fact do not appear in MDC's dataset. See here: https://gisweb.miamidade.gov/landinformation/. The roads are in fact private. See folio 01-4120-004-0260 on MDC Property Appraiser's database here:  https://www.miamidade.gov/Apps/PA/PropertySearch/#/