This guideline is meant to reflect consensus about the notability of highways, based both on the class of highway and individual notability. In a nutshell, highways that are numbered and signed as part of a single, national highway network are generally notable and should have their own articles. It is, however, important to assert each highway's individual notability (historical significance, press coverage, economic importance, etc.) when writing articles.
Highways that are part of a state or provincial (or other primary country subdivision) highway system may or may not be notable, depending on the country. Specific information for various countries is listed below. Some states, provinces, and territories explicitly define separate primary and secondary state highway systems. For those that do not, primary state highways are generally defined to be highways that are numbered as part of a state-wide network and signed.
Highways that are part of a county or municipal (or other local authority unit) highway system are generally not notable unless they satisfy the general notability guidelines. Important exceptions are county highway systems that have a state-wide numbering, which are more similar to state or provincial highway systems. See below for specific country information.
There is no absolute rules for notability that are adhered to for Australian roads.
Motorways, Freeways, Expressways, and roads named with equivalent terms should generally be assumed to have notability. It would be rare that a locally maintained road is notable, though not impossible. Most roads will fit somewhere in the middle on that scale. Use common sense.
Similarly roads may also be notable for reasons other than their position in the road hierarchy or the volume of traffic carried.
Articles for routes are generally not created for Australian roads. See WP:AURDNAME for further details.
The Trans-Canada Highway is notable, and those routes that make up the TCH are notable.
Provincial highways are generally notable, as are primary trunk highways such as:
All other highways built as a freeway, expressway, or autoroute are generally notable as well. Of course, the article should still make some claim of the highway's individual notability, such as historical significance, press coverage, etc.