Office of Planning, Environment, & Realty (HEP)
The National Highway Planning Network (NHPN) is currently a 1:100,000 scale geospatial network database that contains line features representing just over 450,000 miles of highways in the United States. The NHPN contains geospatially referenced information on the National Highway System (NHS), the Eisenhower Interstate System, the Strategic Highway Network (STRAHNET), and NHS Intermodal Connectors. In terms of highway functional class it covers all principal arterials and rural minor arterials. It also has an existing linear referencing system that allowed Highway Performance Monitoring System (HPMS) and National Bridge Inventory (NBI) data to be linked to the network. Using a geographic information system (GIS) this enabled the display of HPMS section information (AADT, pavement condition, number of lanes) and NBI information across the nation or within a region of states. The NHPN has been used to produce maps of the NHS, maintain information of what roads are on the NHS, and serve as a base road network for other mapping and GIS purposes within FHWA. It has also been used for modeling freight flows across the United States as part of the FHWA Freight Analysis Framework (FAF) and as the default road network in the state version of the FHWA Highway Economic Requirements System - State Version (HERS-ST).
A project to improve the scale and accuracy of the NHPN has begun. The new NHPN is will be based on each of the State DOTs' geospatial road networks.
The NHPN is typically used in a geographic information system (GIS) to visually display the network and to perform various geospatial analyses. It is also used in modeling traffic flows in the U.S. at a national scale.