National Transportation Atlas Database (NTAD): Travel Monitoring Analysis System (TMAS) 2013-Present Datasets

The Travel Monitoring Analysis System (TMAS) dataset is from the Federal Highway Administration (FHWA) and part of the U.S. Department of Transportation (USDOT)/Bureau of Transportation Statistics' (BTS's) National Transportation Atlas Database (NTAD). The data included in the GIS Traffic Version database have been collected by the FHWA from the State DOTs through 24/7 permanent count data. Location referencing information was derived from State offices of Transportation. The attributes on the point elements of the database are used by FHWA for its Travel Monitoring and Analysis System and by State DOTs. The attributes for these databases have been intentionally limited to location referencing attributes since the core station description attribute data are contained within the Station Description Tables (SDT). Here is a separate Station Description Table (SDT) for each of the station types. The attributes in the Station Description Table correspond with the Station Description Record found in Chapter 6 of the 2001 Traffic Monitoring Guide. The SDT contains the most recent available for each state and station type. This table was derived from files provided by FHWA. The Station Description Table can be linked to the station shapefile via the STNNKEY field. Some station where not located in the US, and were beyond available geographic extents causing display problems. These were moved to Lat and Long 0,0. This is in recognition that the locations of these where in error, but were moved to a less obtrusive area.

旅行监测分析系统（Travel Monitoring Analysis System, TMAS）数据集源自美国联邦公路管理局（Federal Highway Administration, FHWA），为美国运输部（U.S. Department of Transportation, USDOT）下属美国运输统计局（Bureau of Transportation Statistics, BTS）的国家交通地图集数据库（National Transportation Atlas Database, NTAD）的组成部分。GIS交通版本数据库（GIS Traffic Version database）收录的数据，由FHWA通过全天候永久计数模式从各州运输部采集，其位置参考信息源自各州运输部门。该数据库点要素的属性字段，既可用于FHWA的旅行监测分析系统，也可供各州运输部使用。由于站点核心描述属性数据存储于站点描述表（Station Description Tables, SDT）中，因此该数据库的属性字段被刻意限定为仅包含位置参考属性。针对每一类站点，均设有独立的站点描述表（SDT）；该表的属性字段与2001版《交通监测指南》（Traffic Monitoring Guide）第六章记载的站点描述记录一一对应，且收录了各州及各类站点的最新可用数据，其数据源自FHWA提供的文件。可通过STNNKEY字段，将站点描述表与站点shapefile进行关联。部分站点并不位于美国境内，且超出了可用地理范围，导致显示异常，因此这些站点被调整至经纬度（0,0）处。此举旨在说明，这些站点的原始位置存在错误，故将其迁移至一处不影响显示的区域。