National roads in Castine
The highway network of Castine consists of Autoroutes, Federal Routes, and Parish Highways.
Autoroutes are dual carriageway, controlled-access highways along their entire length with a minimum of two travel lanes in each direction. Autoroutes must also adhere to standards of construction and layout that permit safe travel at speeds of 100 km/hr in urban areas and 120 km/hr elsewhere. The few exceptions to these conditions are found in tight mountain passes where topography requires turns that are too tight to safely be taken at 120 km/hr.
Some Federal Routes and some Parish Highways are also controlled-access along part or even all of their length. Most commonly, though, Federal Routes are dual carriageways with at-grade intersections while Parish Highways are two- to four-lane divided highways. In rural areas, though, Federal Routes may also be no more than two-lane highways. On the other hand, some Parish Highways, for example the Périphérique circling the Saules de Victorin urbanized area  are built to Autoroute standards along their entire lengths. Highways such as these are usually given Autoroute designations eventually, since the designation unlocks Federal funding for upkeep and improvements. As the table summarizes, these peripheral or spur Autoroutes are named differently to distinguish them from their nation-crossing cousins.
Text on the route shields, as well as on Castine highway signage generally, may be displayed in Ingerish, Franquese, or both -- Motorways Castine does not regulate this. Parishes are responsible for signing all roads in their territory, including Federal Routes and Autoroutes, so as usual in Castine practices vary widely. Given the similarities between the languages and the majority-bilingual population, most parishes elect to display only the predominant language of their region on signage. Exceptions are often made for more complex signage, for instance signs giving travelers detailed instructions on a detour.
Signs displaying distances (in km) to control cities and major junctions can be found at 5-10 km intervals on Castine's Autoroutes, more irregularly on Federal and Parish highways. The two examples shown below follow the convention of a black-on-yellow route identifier above a white-on-green display of distances.
Interchange signage generally employs yellow lettering on a sky-blue (midnight blue in some Parishes) background. Distances to at least one waypoint along the intersecting route are usually shown. The example here comes from a particularly infamous circle-type interchange between two Autoroutes, a Federal Route, and one of the more important of Grande Vallee's Parish Highways.
Highway signs near borders generally provide the distance to the first major town along the route in the neighboring country - in this case, Allerswarte in Lapistan and Azurea (LA). This highway (Federal 98) already adheres to Autoroute standards along most of its length and is slated to become an eastward extension to AutoRoute 10 within two years.