2 Principal Arterial – Other Freeways and Expressways
3 Principal Arterial – Other
4 Minor Arterial
5 Major Collector
6 Urban Minor Collector
Additionally, any other highways that are designated as part of the National Highway System
There is also a file, PA_NHS.zip, which is a national dataset including all highways identified as Interstate, Principal Arterial – Other Freeways and Expressways, Principal Arterial – Other, and lower level roadways that are part of the National Highway System.
The following considerations should be adhered to:
The geodetic accuracy and topological structure of the linework have not been evaluated. Use of these data for navigation is not recommended. The user assumes the risk.
National summaries created by aggregating this data may render different results from the information presented in FHWA's Highway Statistics tables. Although the same data was used to produce both formats, GIS processing that linked route data to attribute data may not have been successful and have impacted results in some areas. Data in this spatial format may not completely cover all Federal-aid highways. The information portrayed in the Highway Statistics tables represent the official calculations for national Extent, Condition and performance data and are compiled by enterprise database methodologies.
This information represented in these Shapefiles is a compilation of data collected from many State Departments of Transportation (DOT's). The FHWA extensively reviews the data for consistency and accuracy prior to publication. There may be some remaining discrepancies at the section level. Ultimately, the source of this data is the State DOT's. Subsequent errors that are detected will be passed back to the State DOT for investigation and if confirmed, will be corrected in the following HPMS cycle.
Various formats are used by the DOT's when submitting geospatial data to FHWA. FHWA incorporates these disparate formats into the National HPMS geospatial database. The Shapefile format has been used here as a de facto standard. State-maintained linear referencing systems (LRS) may have been modified to conform to Shapefile formats.
Due to legacy restrictions in the structure of the Shapefile format, the field names have been truncated to 8 characters and may be different as specified by the HPMS Field Manual. The following is a crosswalk from the field names in the Shapefiles to the data items in the HPMS Field Manual.