The evolutionary development of a transportation system requires that implicit and explicit compilation criteria be defined to aid in creating a principal transportation data layer. Implicit compilation criteria are based on various factors that together rate the quality of a transportation route. Lineage is a measure that describes the documented history of a route. It refers to the historical presence of a transportation route as depicted in literature or historical events. Mobility is a measure of the inherent road quality or design, which implies the level of service or accessibility for a particular route.
Alignment is a measure of the rectilinear characteristics of a transportation route.
One of the primary evolutionary features of roads has been based on the ability to straighten roads by overcoming geographic features that once were barriers to travel. The presence of ancillary transportation features, such as bridges, tunnels, and ferries, is one of the factors that support the application of implicit compilation criteria. The presence and nature of the names applied to these routes also helps determine principal transportation routes. The descriptive title of these routes often provides insight into their use. Explicit compilation criteria are based on the cartographic features used on maps that reveal the significance or effectiveness of a route.