Internet GIS and Its Applications in Transportation
(Paper appears in March-April, 1998 TR News)
Zhong-Ren Peng, Ph.D.
Department of Urban Planning
Edward A. Beimborn, Ph.D. Director
Center for Urban Transportation Studies
University of Wisconsin-Milwaukee
Two of the technologies of the 90s, the Internet and Geographic Information Systems (GIS) have changed the ways transportation professionals access, share, disseminate and analyze data and information. The Internet has greatly improved the accessibility and transmission of all types of information including transportation. Transportation data providers, including government agencies and private organizations, are discovering the convenience of publishing and disseminating transportation information on the World Wide Web and many have set up their own Web pages.
The Internet provides transportation professionals easy access to information and data from different sources. They can request and download information and data almost instantly from the Web over the Internet. It is much more efficient than transmitting data through disks. This helps transportation professionals to make more informed decisions.
Geographic Information Systems is being used to integrate, analyze and display spatial data. Because of the spatial nature of most transportation data, transportation professionals found GIS to be a powerful tool to construct and analyze transportation networks, to conduct impact assessment of transportation facilities, and to integrate transportation and land use planning. But GIS software is mostly proprietary. The use of GIS in transportation requires expensive GIS software and extensive user training. Therefore the use of GIS in transportation is somewhat limited to a small number of transportation professionals who have the resources and expertise to use it.
Use of the Internet to access and transmit data (including GIS data) assumes that the user will use the data in their local machine with stand-alone GIS software installed. This is useful in the sense that it can facilitate users to obtain data more efficiently. However, the usefulness of the Internet in this manner is very limited. GIS users have to have the traditional GIS software to view and analyze the data. What if someone does not have GIS software installed in their local machine like the majority of us do? What if a user only needs to view the transportation data and road maps on the Internet? How can we publish spatial data on the Internet and allow the user to perform some spatial analysis without owning their personal GIS software?
The emerging technology – Internet GIS combines Internet and GIS that offers transportation professionals new ways to access, share and disseminate transportation data and information. Internet GIS is a new technology that is used to handle spatial data on the Internet. It is a network-centric GIS tool that uses the Internet as a major means to access and transmit data and analysis tools to enhance the visualization and integration of spatial data. It has new features that allow transportation agencies to publish spatial data on the network for public access, and allow transportation professionals to more easily share data and to conduct transportation analysis across a network as well as at an individual site.
Features of Internet GIS
Internet GIS has features that have promising transportation applications through its ubiquitous accessibility over the Internet. Users do not have to buy expensive GIS software but can access GIS data and analysis functions over the Internet. Thus, Internet GIS is also called "GIS to the masses". This makes it easier for transportation agencies to disseminate transportation information to the public. The user-friendly interface of the Internet GIS can also facilitate data sharing within and between transportation agencies.
The second feature of Internet GIS is the interactivity between the users and the spatial data. Interactive GIS offers interactive maps rather than static map images on the Web. Users can work with the maps interactively by performing conventional GIS functions such as zoom, pan, identify and queries. The maps are alive on the Internet.
The third feature of Internet GIS is that it can incorporate up-to-date, real-time information. This is especially important for the applications in intelligent transportation systems. Several applications have been developed that display real time traffic information. More applications can be developed in real time travel information systems, transit information and trip planning by linking Internet GIS with automatic vehicle locators and automatic passenger counters.
Two Kinds of Internet GIS: Server Side and Client Side
The building block of the World Wide Web, HyperText Markup Language (HTML) does not directly support spatial data in the form of maps. Therefore, Internet GIS needs an "interpreter" on the Web to use GIS data that cannot be recognized by the HTML itself. This "interpreter" is the core component of Internet GIS. It is used to interpret user input from the Web page to a language that the GIS software can understand. It can be located at the server side as well as client computer (user) side. If the "interpreter" is located at the server side, it is called server–side Internet GIS; whereas if is located at the client computer, it is called client-side Internet GIS. Server-side Internet GIS relies on the host computer to perform all GIS analysis, while client-side Internet GIS perform GIS analysis and processing on the Web browser on the user’s local machine.
Server-side Internet GIS depends on the server to perform analysis and generate output. The user at a Web browser client initiates the request that is sent across the Internet to the server. The server processes the request and sends ba ck the result to the client. The most frequently used server-side application is to use Common Gateway Interfaces (CGI) script to link the HTML with GIS server. The CGI script acts as the "interpreter" to connect user input and GIS server. Figur e 1 shows the working process of server-side Internet GIS.
The advantage of the server-side Internet GIS is that it can handle large databases at the server and answers specific questions for the public. But it offers little flexibility and interactivity to the end user. The user cannot directl y work with the data as one does with the stand-alone GIS software. The limitations of the normal data transmission protocol prohibit the development of more advanced analysis tools. It can merely be used for static spatial query and display.
Client-side Internet GIS allows GIS analysis and data processing to be done on the Web browser in the user’s local machine. GIS data and analysis tools initially reside in a server. Users usually request data and processing tools from t he server, which sends the data and analysis modules to the client for local processing. Client-side applications include three major technical approaches: GIS plug-ins and helper programs, ActiveX Controls, and GIS Java applets. Figure 2 shows the workin g process of client-side Internet GIS.
The client-side Internet GIS offers more flexibility and interactivity between the user and the maps than the server-side applications. GIS plug-ins, helper programs and ActiveX controls extend the capability of HTTP to directly handle GIS data. The end users can view GIS data and perform simple analysis on the Web just like they do on local GIS software. But client-side Internet GIS has difficulty to handle large database
Internet GIS applications in Transportation
Internet GIS provides a perfect tool to access, disseminate and visualize transportation data. Any information that can be displayed on a map such as highway and transit traffic levels, construction conditions, weather information and s o forth can be transferred using Internet GIS. It also offers the potential for data sharing and transportation analysis over the Internet.
Interactive Road Maps
One of the major characteristics of Internet GIS is the interactions between the user and the spatial data. Users can perform GIS functions such as zoom, pan, query, and identify. This is especially useful for displaying road maps on th e Internet. In addition to paper maps, State DOTs can also publish interactive road maps on the Internet. Users can zoom into (or out of) a specific area, inquire a specific address and identify a particular road links. This electronic map on the Interne t is more convenient to use than the traditional paper maps. The distribution of Internet maps is also much broader than the paper maps generated by state DOTs. Anyone with a web browser can get immediate access to a road map of any portion of a state th ey are interested in.
Interactive road maps provide both search and browse functions. Users can search for a specific road and/or address, which results in a map that is centered around the search address. Once the user has the map, the user can zoom in or o ut, and pan around to browse the neighboring areas.
MapQuest (http://www.mapquest.com/) provides a good example of interactive mapping services available on the Internet. With MapQuest, the user can search for any address in the United States by imputing the street address on the Web page. MapQuest will then present a map window as shown in Figure 3. The user can further zoom in different scale such as a street level, city level or state level. The contents of the map changes acording to the map scale requested. Similar services can also found in Yahoo Maps Web site (http://www.proximus.com/yahoo/).
Figure 3. Snapshot of Internet map service by MapQuest
Real time information on road conditions and road construction
It is also useful to provide interactive maps on the Internet so that people can find their way around. It is more valuable to provide real time information on road conditions such as road construction and weather-related road condition s. This will reduce the burden of the 1-800 phone road services. With Internet GIS, the road conditions can be easily updated and maintained. A weather-related road condition can be linked with weather information and changed in real time.
The Bureau of Automation Services at Wisconsin Department of Transportation is implementing an Internet GIS site to disseminate road closure information on the Internet usin g a piece of Internet GIS software: MapObject Internet Server produced by Environmental Systems Research Institute, Inc. The road closure information can be updated by authorized transportation agencies and is instantly available on the Internet.
* Being developed for Wisconsin Department of Transportation by Seventh Generation Information Systems.
Figure 4. Snapshot of road closure information on the Internet in Wisconsin DOT
Everyone realize the importance of sharing information within and across transportation agencies. But sharing data and information is difficult even within agencies, and sharing information across agencies is virtually unknown. This is partly because there is no easy way to share spatial data, partly because different data may not even be compatible. One has to call around to find out who has what data, make a request and wait for days or even weeks for the data diskettes to arrive.
That may soon change as Internet GIS enables agencies publish their data on the Web. Internet GIS offers an ideal tool for governmental agencies to share data within and across agencies. For example, a highway department can publish the ir real-time traffic information on the Web, and this information can be readily used by transit agencies for transit dispatch adjustment. Land use planning agencies can publish their land use and zoning maps on the Internet, and environmental reservation agencies can also publish their maps of environmental sensitive areas on a Web page. This information can be used by transportation planners in the development of transportation plans, and vice versa. This open data sharing system will greatly reduce the barriers within transportation departments and across other agencies.
Internet GIS offers transportation professionals at different places to be better informed by simply looking at a Web page. For example, the following map on the Internet shows the availability and accessibility of transit service to a neighborhood in Milwaukee. Transit agencies and social service agencies can share this information.
Figure 5. Snapshot of accessibility to transit service at Milwaukee Midtown area.
Public involvement of transportation planning
The interactive Internet GIS offers an excellent channel for public involvement in the transportation planning process. Transportation planning agencies can publish information on planned road expansions or new transit routes on the Int ernet. The public can interact with the road plan and offer their input directly from the Web. Rather than going to town-hall meeting, the public can directly access the information right from their home. Hopefully, this would give the public more input i n the transportation planning process.
Internet GIS and Intelligent Transportation Systems
Internet GIS can be an important tool in the development of Intelligent Transportation Systems. It can be used to disseminate real time travel information and to make real-time trip plans.
Real-time travel information systems
Interactive Internet GIS is a perfect presentation tool of real time travel information once it is linked with real-time traffic information. Several state DOTs have created real-time traffic maps on the Internet using either server-sid e or client-side Internet GIS technology. For example, under the ITS model deployment initiative, Smart Trek at Seattle, Washington created a TrafficView (http://trafficview.seattle.sidewalk 1.com/) to present real-time traffic information on the Web. Users can view the traffic flows on the entire freeway system in the city. They can also zoom into a smaller area for a more detailed view. Users can quickly find the travel speed alo ng a specific link on a freeway. The road link is also connected with real-time video snapshot so that the user can see the traffic flow.
Figure 6. Snapshot of real-time traffic information in Seattle.
Advanced trip-planning systems
The graphic presentation of Internet GIS makes it an ideal tool for travelers to plan their trips. By linking Internet GIS with real-time traffic information, a traveler can plan a trip on the Internet based on his/her origin and destin ations, as well as real-time traffic. For example, travelers can plan their travel itinerary according to real-time traffic conditions in Seattle.Sidewalk Web page (http://trafficview.seattl e.sidewalk1.com/). Similarly, a transit user can also plan his/her transit trip on the Internet based on the real-time transit schedule and bus locations by linking with Automatic Vehicle Locator.
Any new technology usually has unintended consequences. Internet GIS provides a way for transportation agencies to share information with other agencies and the general public in ways they have never done before. This can raise many questions w ithin those organizations in how they deal with others and to what extent are they willing to share information that was not so readily available in the past. Transportation agencies may be forced to think about how they interact with others and the how they control information. This may make some within transportation agencies uncomfortable because it can disrupt existing relationships and the internal control of the organization. To the extent that ‘knowledge is power’, procedures to make information available to more people may be seen as a threat to power. The transition from an organization with tight controls on the release of data to one that has open access will be difficult and involve issues far beyond the technology.
In the long run the transition to Internet GIS and wide access to information will likely be positive. There are many significant immediate benefits to users, which can help improve transportation services. Greater scrutiny of information by others w ill mean that more effort will be made to provide valid and useful data. This will improve procedures and techniques over time. Agencies will need to think about this to assure a good transition to more open access to their information.
Internet GIS is a new technology that is used to display and analyze spatial data on the Internet. It combines the advantages of both Internet and GIS. It offers public a new means to access spatial information without owning expensive GIS software. Since most transportation data are spatial in nature, Internet GIS provides great potential as a powerful tool for transportation agencies and professionals to disseminate transportation information to the public via the Internet. It can als o facilitate spatial data sharing within transportation agencies and between transportation department and other government agencies. The easiness of sharing data will have potential impact on governmental agencies in general and transportation agencies i n particular.