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On the move
Walk into any store in your neighborhood and count the number of items that have come from only 5 or 6 miles away. Not many. Most come from dozens, hundreds, or thousands of miles away. Many come from halfway around the world. That means those items have been on trucks, planes, and then trucks again, and possibly in holds of ships or the freight cars of trains before they got to the store. Then they go home with you in a car, bus, or train. And while more and more people are hooking up computers so they can work at home, most of us still drive to work. Even if we work at home, we still drive to the store and the theater, we still fly across the country to visit relatives, or across one ocean or another to snap photos of exotic places, eat exotic foods, and meet new and interesting people.
Mile after mile All this traveling takes an enormously complex infrastructure-roads, runways, rails, harbors, docks, bridges, overpasses, signs, signals, fences, railings-mile after mile of them, in crowded cities and empty countrysides, through pitiless deserts and snowbound mountains, along hurricane-wracked coastlines, and through fault-ridden valleys. Pounded and smashed by trucks and cars, lashed by wind and snow, everything in the whole system is used and abused, and everything in the whole system needs constant attention to stay in good repair.
Simple, but very powerful To understand the complexities, and to stay ahead of the ceaseless rounds of repair, redesign, and new construction, transportation managers have increasingly turned to geographic information systems, or GIS. A GIS, simply put, is a spatial database. Geographic locations are stored as sets of mathematical coordinates. Information about the locations is stored in tables that are linked to the locations. Different spatial information is stored in different files, or layers. These layers can be viewed simultaneously, and in just about any combination. The system can also be queried to extract information from these layers. Which intersections have the most accidents, and which kinds of accidents occur most frequently? What time of day do they usually occur? These are some examples of questions a GIS database could answer. You can also, of course, use a GIS to make maps. Maps of street networks, of train lines, of bus routes. Not just static maps, either. Because digital maps can be updated constantly, you can make maps that show the current position of a train, for example, or a snowplow, or a fire truck. You can make maps of routes that change from day to day.
Anywhere you want to be GIS describes a broad range of software products, from server-based technologies like ARC/INFO to desktop solutions like ArcView GIS to Internet solutions like MapObjects Internet Map Server. In the transportation industry, GIS is useful because it can merge data regardless of the original measuring scheme used to capture it. This unique capability is possible because GIS systems have a linear referencing system that assigns locations to objects according to their distance to or from something else. This linear system recognizes all points along a highway or railway, not just one-tenth mile markers or intersections, for example, so the user can "query" or "view" any place along the network. In current versions of GIS software, this linear referencing capability is called dynamic segmentation (or dyn seg for short).
Keeping highways in good repair Transportation departments use GIS to design and construct highways, taking into account not only the physical realities of slope and drainage, but less tangible qualities like fragile environments and scenic beauties. Safety engineers use GIS to look for places where the same types of accidents occur so they can redesign the roads or change the signs and signals. Highway departments maintain roads and manage their fleets of snowplows and line-painting trucks with GIS. Information about potholes, cracks, and repair schedules is maintained in the spatial database. Even complaints about the roads from drivers and reports of accidents from police departments are part of the database and thus part of the process of deciding what to repair and when to repair it.
And traffic flowing smoothly Urban traffic engineers use GIS to keep traffic moving smoothly and safely along the streets of their cities. Diagrams of intersections and inventories of signal control equipment are integrated into their system databases. And the locations of signals are tied to streets, accident files, and traffic count data. GIS is used to predict future congestion and pollution, too, and to solve those problems as well. GIS gives engineers the data-based means to encourage people to reduce their dependence on new roads: to stop driving alone and ride in carpools, use public transit, ride bicycles, stagger work shifts, or even work at home. GIS helps match carpoolers by where they live and work, by the hours they work, and even by whether they prefer to ride or drive, or to smoke or not. Recently, GIS has been incorporated into the emerging area of intelligent transportation systems (ITS), where traditional basemaps are updated in real time with information on lane closures and traffic levels, which is then provided to traffic operations, enforcement, and emergency response teams.
Information-gathering tools With GIS playing a larger role in the transportation industry, state and local governments, as well as public transit operators and shipping companies, have a wider variety of instruments and tools for collecting and processing data. In-pavement sensors, red-light cameras, and closed-caption television (CCTV) equipment are being installed at intersections or along highways to help detect the speed and volume of traffic flow and adjust signs and signals accordingly. Global positioning systems (GPS) are being installed in taxis, trains, and even snowplows. Onboard computers can collect information from a vehicle’s operating system and upload it by satellite link, along with the vehicle’s position, obtained by a GPS receiver. All of the above are examples of data that can be loaded into a geographic information system.
Commuter world Railways around the world use GIS to manage real estate and facility databases to organize data for several different departments: engineering, emergency operations, and railway maintenance, among others. They use GIS to keep track of where locomotives are as they run, so any problems (detected with onboard sensors) can be repaired immediately at the nearest service facility. Public transit agencies use GIS to plan and analyze bus routes, combining route databases with residential and business demographics to find ways to get more riders and to lower costs. Commuter railways, subways, and light rail operators are starting to provide electronic maps to customers, at stations and over the Internet, showing train positions and arrival and departure times.
Airports as good neighbors Airport authorities use GIS to plan runways and parking lots, of course, but they also use its three-dimensional capabilities to look at flight paths and the noise contours generated by passing planes. With this information, they can plan landing and takeoff paths that stay clear of tall buildings and away from residential areas. Airlines use these systems to analyze flight routes and plane capacities to see where they might add a route or change a destination and to plan rerouting when weather forces some airports to close.
The road ahead Current estimates show that approximately ten thousand transportation industry professionals use GIS to plan, design, construct, operate, and maintain roadway, rail, aviation, port, and fleet facilities around the world. As GIS becomes more commonplace in their projects, and new applications are found for the technology, its use is expected to triple in the next three to five years. Public access via the Internet will allow spatially enabled transportation databases to be made available to a majority of citizens. Clearly, GIS is a critical tool for today’s and tomorrow’s transportation manager, offering as it does the opportunity to communicate more quickly and effectively with associates, policy makers, contractors, neighboring jurisdictions, and the public.