Citation:

Description:

The Digital Line Graph (DLG) A layer in the Environmental Protection Agency (EPA) Spatial Data Library System (ESDLS) National 1:2,000,000 scale library, provides the interstate and primary state highway data, derived from a subset of the 1991 United States Geological Survey (USGS) 1:2,000,000-Scale Digital Line Graph (DLG) Data CD-ROM. The DLG A layer is an ARC/INFO line coverage. The DLG A layer provides data for applications that need to display interstates and primary state highways at small scales. The EPA GATEWAY/GIS 4.0 and ESTAT applications are currently the only applications that use this data. The DLG A layer is intended to be used with ARC/INFO GIS applications that require an ARC/INFO coverage containing interstate and state highway data, at small scales.

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Record Details:

Record Type:DATA SET

Product Published Date:04/07/1998

Record Last Revised:12/10/2002

Record ID: 6045

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Quality Assurance:

Title :1991 USGS DLG INTERSTATE AND PRIMARY STATE HIGHWAYS FOR THE CONTERMINOUS UNITED STATES

Data Use & Constraints :The EPA Systems Development Center (SDC) Product Assurance (PA) Team performed quality assurance and quality control against the DLG A layer data. The PA Team checked for positional and visual accuracy, and logical consistency within the defined projection system. Positional and visual accuracy and logical consistency were verified by viewing each state/ region tile in ArcView 2.0. PA verified the existence of the DLG A layer for every tile, and also checked the DLG A layer against the other data layers in that tile (DLG H, DLG CNTY_POL, and DLG STATE_POL). If any holes or inaccuracies occurred in the data, a Test Incident Report (TIR) was generated. Each view was saved as an .xwd file as verifiable objective evidence of PA efforts. This data is used and made available through Region 10 XINFO mapping applications when large area maps (>1:250,000) are scaled to fit 15 x 11 page sizes.