National Transportation Atlas Databases: 2004

The National Transportation Atlas Databases 2004 (NTAD2004) is a set of nationwide geographic databases of transportation facilities, transportation networks, and associated infrastructure. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the related attribute information for these features. Metadata documentation, as prescribed by the Federal Geographic Data Committee, is also provided for each database. The data on this twin set of compact disks (CDROMs) support research, analysis, and decision-making across all modes of transportation. They are most useful at the national level, but have major applications at regional, state, and local scales throughout the transportation community.

This product is distributed in shapefile format. The shapefile is an open format created by the Environmental Systems Research Institute (ESRI). You can find additional information about the format at: www.esri.com/library/whitepapers/pdfs/shapefile.pdf

The NTAD2004 databases are designed for use within a geographic information system (GIS); however, the attribute data for each dataset can be accessed in any database, spreadsheet, or other software package. This information is stored in dBASE format. Because of spreadsheet limitations, many of the larger dBASE files will not open correctly with spreadsheet software. It is important to note that users who manipulate attribute data outside of their GIS may alter the shapfiles' linkage between the attribute and spatial data.

2004年国家交通地图集数据库（NTAD2004）是一套覆盖全国的交通设施、交通网络及相关基础设施地理数据库。这些数据集包含各交通方式网络和多式联运枢纽的空间信息，以及这些要素的相关属性信息。每个数据库还提供了联邦地理数据委员会规定的元数据文档。这套双光盘（CDROM）中的数据支持所有交通方式的研究、分析与决策制定。它们在国家级层面最为实用，但在交通领域的区域、州及地方层面也具有重要应用价值。

本产品以shapefile格式分发。Shapefile是环境系统研究所（ESRI）创建的一种开放格式。有关该格式的更多信息可访问以下网址获取：www.esri.com/library/whitepapers/pdfs/shapefile.pdf

NTAD2004数据库旨在地理信息系统（GIS）内使用；不过，每个数据集的属性数据可通过任何数据库、电子表格或其他软件包访问。该信息以dBASE格式存储。由于电子表格软件的限制，许多较大的dBASE文件无法通过此类软件正确打开。需注意的是，用户若在GIS之外操作属性数据，可能会改变shapefile中属性数据与空间数据之间的关联。