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GIS on the Great Plains : Innovative Transportation Planning Tool Assists Growing Midwest City
by
Jim West, Kip Strauss, With a population of about 90,000, Olathe is the second largest among the 21 communities in prosperous Johnson County, Kansas. Since the 1950s, Olathe's population has quadrupled, and today is the 5th largest city in the state. It is located just 20 miles southwest of downtown Kansas City, with all of the cultural advantages of a major metropolitan area. As leaders of a thriving city, Olathe officials became interested in developing a new method by which their travel demand model could be used to identify short and long-term transportation deficiencies. The system in place identified roadway improvement projects for the Capital Improvement Plan in a somewhat arbitrary manner. In response, HNTB Corporation, The Problem Last year, a Street Network Study of Olathe’s future needs
identified anticipated roadway capacity deficiencies for the next 20 years. The
city’s five-year Capital Improvement Plan (CIP) was assigned with pinpointing
and prioritizing needed roadway improvements, although these were previously
designated in a somewhat random manner for the CIP. In consequence, the city’s officials Olathe’s Public Works Department used a travel demand model as an effective means of estimating future travel demand on city streets. Roadway segments that are projected to carry more traffic than they were designed for become primary candidates for future improvements. The output from the model is more than just a forecasted traffic volume on a roadway link: other important traffic operation measurements such as vehicle speed, number of lanes, lane capacity, vehicle delay and travel time are also generated. This tool, although available for many decades, falls short of allowing Olathe’s engineers and planners to analyze, manipulate and display the data clearly. Getting important data into and out of the model had previously been a major hurdle. These and other limitations in the system complicated the input, analysis and presentation of the model results. Working Together In the The company submitted a proposal suggesting the
integration of Olathe’s citywide geographic information system (GIS HNTB and Olathe officials worked together to develop digital land use information based on existing maps and assumptions about future land use potential from historic building permit files. Meetings with city staff and other stakeholder agencies were organized to help develop data necessary for the travel demand model. How TMSA Works The integrated software application HNTB prepared for Olathe is a GIS application called TMSA. TMSA provides a link between Olathe’s GIS (which uses ESRI’s ArcView software Avenue programming language) and its travel demand model (TMODEL2) in combination with C++ and Visual Basic for Applications programming languages. The TMSA application allows city planners and engineers to exchange data between the travel demand model and the GIS. Land use, building permit information, traffic analysis zones (TAZ), as well as other demographic information stored in the GIS, can be used to develop and test different land use growth scenarios. This data can then be uploaded to TMODEL2 for analysis in a fraction of the time. In addition, travel demand results generated by the model can be downloaded to the GIS for more thoughtful analysis and display of model results. The system’s design enabled Olathe officials to determine land use forecasts using the city’s database of building permit data and to project land use growth around the city. A travel demand model can be used to test “what if” scenarios with immediate feedback about specific local and system roadway impacts. Linking a GIS to a travel demand model allows planners and engineers to analyze and present data in a clearer and more meaningful manner. The application The application also Olathe’s Viewpoint In a fast-growing community
like Olathe, it is important and critical to have the city’s travel demand
model as up to date as possible. Olathe
uses its travel demand model results as a guide in developing the five-year
Capital Improvement Plan. Too much of
an investment is made in the modeling effort to see it become outdated as soon
as the results were adopted for a given horizon year. The fast pace of growth in Olathe requires an updating system
that can be quickly modified, user friendly, and reliable. With TMSA, Olathe’s traffic engineer, Alonzo Liñan, P.E., has been able to develop unique applications for improved transportation and land use planning. “The model link with GIS has
provided the city with the opportunity to quickly update major developments and
changes in land use or development trends,” explains Liñan. “TMSA also allows city
staff to more dynamically display the results of model runs in a format that is
already familiar to most of its viewers.” When transferring TMODEL2
output to the GIS platform, data is converted into a format that ArcView can
read, as links in the travel demand model are tied to links in the GIS. The
results are visually displayed in a real-life manner rather than as archaic
representations of nodes and links. “This two-way data exchange helps to keep the model current,” Liñan stated. “The TMSA platform gives city staff the flexibility to easily and quickly perform ‘what if’ scenarios based on network and land use modifications. This is very useful since it now only takes a fraction of the time to perform these analyses. The result is a tool that serves the city and community with an improved transportation planning process.” Conclusion Innovative transportation planning tools help
decision-makers become better informed about
March,
2000 |
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