State Highway Network Postmiles

The reason for this is to best support independent alignments AND to meet Federal Highway Administration requirements for every state's Linear Referencing System. To accommodate division of entire signed routes into multiple Postmile Routes, LRSN_Postmile is configured as a Roads and Highways "Line Feature", where every individual Postmile Route that comprises a Signed Route is tagged with a "Line ID" common to the Signed Route.

This supports the ability to perform Dynamic Segmentation of linear events that begin on one Postmile Route and end on another, and the ability to automatically derive the Odometer Network directly from the Postmile Network. The Postmile Network is one of three Roads and Highways Networks maintained in Roads and Highways by Caltrans. The other two are the Odometer Network (also State Highway System only, and derived from the Postmile Network) and the AllRoads Network, which represents all public roads in California (not just state highways).