Factors Affecting the Use of GIS in Urban Transportation Planning and Management

Equipment is needed for a range of activities -- from data collection to data analysis. The main requirement is a workstation. However, ancillary equipment may also be necessary. A digitizer is required for converting hard copy data to digital format. A GPS data logger may be required to collect field data. The use of hand-held field technology is also becoming popular. The advent of web-enabled GIS has resulted in web servers being added to the list of GIS requirements (GIS Lounge 2004).

Software for GIS applications is available from numerous vendors. Such software is generally capable of multiple tasks. For specialized tasks, extensions can be acquired or developed in house (GIS Lounge 2004).

As alluded to above, two primary types of data are used in GIS applications. These are geo databases (vector & raster types) and attribute data (GIS Lounge 2004).

The design of the technology enables the storage of the spatial features in a coordinate system that is referenced to Earth. Attribute (or descriptive) data are then associated with the spatial features. The spatial data and associated attribute information are layered on top of one another for viewing and analysis. The technology makes it possible to efficiently and holistically view multiple items of interest within a particular geographic area (FHWA 2004).

Data capture/entry involves manual digitizing and scanning, requiring the use of photogrammetric stations, coordinate geometry, global positioning system (GPS) receivers, digital cameras, satellite sensors, radar sensors, and thermal infra-red imaging devices. The integration of disparate data is carried out in the form of direct conversion of data from one system to another, and translation of data via standardized neutral exchange file formats. The spatial management (i.e., editing, topology building, edge matching, aggregation, and generalization) is carried out by customized software while attribute data might be managed by a database management system.

Advances in data capture technologies are responsible for reducing costs. In the past, high cost has been an impediment to the application of GIS in the transportation field. A variety of spatial referencing systems are used by transportation agencies for collecting data. Improved methods for the integration of data into a common referencing system for use in GIS-T are necessary for display, and for report preparation (TAC 1995).

User interfaces are driven by command languages, menus, and windows. Outputs include maps and data in variety of formats. The evolution of automated mapping has been supported by surveying, mapping, and remote sensing technologies, as well as advances in computer hardware and software. Progress in the development of GIS continues to be supported by such technologies.

Technology platforms are another area where innovations have helped improve GIS-T applications. These innovations include workstation technology, distributed processing and distributed database management. Further developments in this area will enable the integration of GIS into an overall agency-wide technology strategy.

As a database management system, a GIS-T is effective in capturing and analyzing data for a variety of planning and management applications. Such applications usually require that information on transportation analysis zones, demand for passenger and freight movement, passenger and freight vehicle flows, transportation networks, routes, schedules, and transportation system performance be stored, displayed, and analyzed at various spatial scales.

The transportation data structures that can be supported by a GIS-T include nodes, links, networks, paths, and origin-destination matrices. Query analyses allow information to be readily obtained and summarized, such as information on accident locations or various map features. Moreover, through dynamic segmentation, which is a method of partitioning lines or areas in a GIS database, selected attributes can be displayed (e.g., streets segmented by traffic volume and road condition) (Caliper Corp. 2004, 1996).

Several GIS technology and service related developments are taking shape in North America (Fletcher 2000, Peak 2000). These are noted below.

  • General information technology and market forces are changing rapidly. For example, the internet is producing an entirely new computing model,
  • Owing to general transportation administration trends, there is a tendency towards outsourcing, privatizing, and decentralizing activities. This is resulting in an increased need for specialized consulting services.
  • GIS-T markets, products, and technologies are changing. Examples of such changes include the development of mobile terminals, map-based yellow pages, trip planning and travel direction applets, vehicle tracking and routing applications, and other real-time products, services, and applications.
  • GIS-T applications and services are becoming diverse (e.g. shift from infrastructure development to asset preservation and transportation operations).
  • There is an increasing demand for spatial data, information, and knowledge (i.e. global data on demand, interoperable systems, location reference schemes, high resolution data).
  • Integration of systems is on the rise (e.g., GIS, web technology, and intelligent transportation systems (ITS)).
Recent technological developments in GIS and related systems/services are presented in Figure 3. These are organized into hardware, software, web technology and specialized combinations. Selected highlights are described next.

Geospatial information technologies are being used as new approaches for data acquisition. They are also being used as advanced tools for transportation planning and operations. For example, Thirumalai (2003) described how to expand ITS technology services through integration with commercial remote sensing and spatial information technologies. The implication is that commercial remote sensing and spatial information technologies can be used as imagery-based tools and systems for the transportation services market.

Bargiela and Berry (1999) describe a GIS-based interface for advanced traffic control. Such a system can be used for many purposes, including interrogation about real-time traffic flows in the network. Web-based systems for displaying real-time traffic flow conditions have also become available (Globis Data 2004).

Clearly, technological change has been rapid and is expected to continue at this pace. In combination with other factors, improvements in technology are likely to lead to increased use of GIS in urban transportation planning and management.


Figure 3: Examples of Recent Technological Developments




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