An appreciation for transit demand analysis in urban areas requires an understanding of not only what factors influence the demand for public transportation services but also some of the practicalities inherent in empirical studies. Our efforts to teach undergraduate students some basic principles about travel and transportation through data analysis using the ArcInfo and ArcView software have led us to identify some interesting practical matters which get in the way of an easy path to understanding. We have undertaken some experiments to establish some of the impacts of data availability and the data types and algorithms available in the software. We aim to demonstrate the impact of spatial data type and necessary manipulations to select areas for analysis, obtain statistical summaries and measurements, and undertake spatial interaction modelling. After presenting a schema of possibilities, the paper will give examples of experimental results for selected tasks: (1) measures of distance, (2) the creation of accessibility surfaces, (3) the assignment of aggregates for polygons to the bounding arcs of polygons, and (4) the assignment of scalar quantities from one set of polygons to a different set. The statistical results from the exercise of different procedures or assumptions cast light on the pitfalls of using data of certain types, e.g. polygon counts when demand is needed for arcs, and the limitations of the underlying data models. In this way students can obtain an appreciation for the realities of data analysis and the sensitivities of model algorithms to the properties of the input data. This project is supported by the U.S. Department of Education, the University of Maryland, and the Esri Inc.
This study explores the potential uses of Geographic Information Systems (GIS) in Federal Transit Administration's (FTA) Major Investment Studies (MIS) process, with a particular emphasis placed on alternatives analysis. In identifying the corridors for major transit investments, flow analysis in ArcInfo Network module can be used to determine those corridors meeting the minimum requirement of having more than 15,000 daily riders as required by FTA. In addition, buffering analysis can be conducted to make sure that the corridors selected have sufficiently high population and employment densities. In developing do-nothing, TSM (Transportation System Management), and major investment alternatives, GIS can be a strong tool in displaying transit networks with line numbers, stops, frequency, speed and other operating characteristics annotated. This will greatly visualize different alternatives. In comparing different alternatives, GIS can effectively do buffering analysis around station locations within a specified walking distance (e.g. a half-mile radius). Moreover, proximal analysis can be performed to identify those sensitive land uses adjacent to the transit project, e.g. cemetery, earthquake faults flood plains, and so on. GIS can be used to overlay transit line (line feature) on the top of zonal socioeconomic data (polygon feature). This will help maintain a good compatibility between transportation and land use. In assessing environmental impacts of transit project, GIS can not only identify nearby sensitive land uses, but also conduct spatial aggregation to generate corridor-level mobility and air quality results. For example, TAZ-level (TAZ stands for Traffic Analysis Zone) VMT and VHT can be aggregated into corridor-level VMT and VHT. Likewise, grid-level emission figures can be aggregated into corridor-level emission figures. In summary, GIS can be a very powerful tool in assisting FTA's Major Investment Studies (MIS). This is especially important for the Los Angeles area, because so many heavy rail projects need to go through MIS process as mandated by FTA.
This paper discusses the implementation of a Regional RideMatch system using ArcView 2.1 The original development of this system, GIST/Rideshare, took place to meet the requirements of the RideFinders Network (now Commuter Connections) of the greater Washington, DC area. Centered on the District of Columbia, the RideFinders service area stretches south to Richmond, Virginia and north to the Baltimore, Maryland metropolitan area and its GIS database includes more than 300,000 street segments and 8,000 landmarks. The selection of ArcView as the basis for this system was motivated by the need for ease of use by non-technical users such as rideshare operators, and the need to integrate the ridematching with the rest of the agency's GIS functions. Recently, the Association of Monterey Bay Area Governments selected this GIS-based solution for their rideshare program. Much of the customization of the software to meet Amber's particular requirements will be done by AMBAG staff, demonstrating the flexibility that can be built into ArcView applications. With the release of ArcView 3.0, significant enhancements-such as routing from a specific street address to another street address instead of from node to node-will be possible.