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About INTDASEach year, more than 500 of the nation's transit agencies report data to the Federal Transit Administration (FTA) for inclusion in the National Transit Database (NTD)--a uniform data set required by the Urban Mass Transportation (UMT) Act as a prerequisite for the nation's transit systems to receive the FTA grant funds. Known formerly as the Section 15 database, NTD includes data on transit organization characteristics, vehicle fleet size and characteristics, revenues and subsidies, operating and maintenance costs, safety and security, vehicle fleet reliability and inventory, and services consumed and supplied. These data have been used extensively to derive values for transit performance measures and have become the sole source of standardized and comprehensive data for use by all constituencies of the transit industry. As a major source of performance data for the transit industry, an important application of NTD has been to perform trend analyses that require the use of multiple years of NTD data. However, accessing multiple years of NTD data is a rather tedious process. One major reason is because NTD data are collected and distributed annually on separate files. To perform a trend analysis, for example, one must learn about the file structures that may vary from year to year, identify the specific variables of interest from the vast number of potential NTD variables, and then extract the corresponding data values from the specific files for the specific transit systems. For a ten-year trend analysis, for example, this process must be repeated ten times, one for each data year. After the trend values are separately extracted for each of the ten years, they must be entered manually into a spreadsheet or a statistical program for analysis. This process is very cumbersome and is prone to errors. Clearly, a solution is to develop an integrated database system that (1) combines the individual NTD data files from multiple years into a single, standardized database, and (2) provides customized tools for quick and easy data retrieval, visualization, and analysis. The Integrated National Transit Database Analysis System (INTDAS) was such a system. It does not only allow the users to perform trend analyses quickly, but also peer comparisons and other general data inquiries of the database within only a few mouse clicks. The current version of INTDAS integrates the 1984-2006 NTD data for all transit systems reported to the NTD program and provides customized tools for easy data retrieval, visualization, analysis, and transfer. Major INTDAS features include:
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