Identify Equilibrium of Land Use and Transportation Investments Using Spatiotemporal Analysis Tools
The importance of land use and transportation interactions is well recognized in the literature. The impact brought by transportation systems on land use is mainly improved accessibility, which in many cases encourages new land developments. Increased land use density and intensity in turn result in traffic congestion, demanding improvements in transportation systems. There have been a number of studies that identified links between transportation projects and new land developments, particularly around fixed guideway transit stations and a few highway projects. These studies typically examine the land use link to transportation projects using some kind of overall economical indicators that are not location specific. Land use changes are caused by many factors, including social, political, environmental, and economical factors, in addition to increased accessibility due to transportation improvements. The relationships between land use and transportation thus are complex and still not well understood. This is why few travel demand models have the capability of handling these interactions. With the Clean Air Act Amendments of 1990, travel demand models have been challenged in courts on their abilities of assessing the impacts on land use development and consequently air quality due to transportation improvement plans (e.g., Citizens for a Better Environment v.s. Deukmejian, et al. and Sierra Club v.s. Metropolitan Transportation Commission, et al. in San Francisco Bay area). The TEA-21 legislation also requires a better understanding of the relationship between transportation and land use as well as a better linkage between transportation investments and desired land uses.
The recent development of the Urban Land Use Allocation Model (ULAM) has provided a useful tool for the land use planners to better understand the process for future land use allocation and use the methodologies provided in ULAM. Beside incorporating land availability and market trend in the model, ULAM also uses congestion resulted from FSUTMS as an indicator of accessibility. Currently, ULAM and FSUTMS are not integrated and feedback between the two models are not supported. Although it may not be technically difficult to develop an interface to allow run-time interaction between the two programs, the critical question is how the two models should be linked since effects of land use on transportation and vice versa may not be felt until many years later. More specifically, these questions need to be answered: what is the time lag between transportation improvement projects and land development; how accessibility affects the rate at which land use intensity changes; what is the spatial pattern of land development; how does transportation system respond to new land development; and how land developments change travel patterns.
Due to the time lag between transportation improvement projects and land use changes induced by these projects, to answer the above questions requires the collection and examination of historical data on both transportation projects and land use. In the past, because of the lack of digital data of historical land use changes and transportation systems, as well as the lack of the necessary analysis tools, studies on land use and transportation have been limited to a particular project or a particular area of interest and the spatial and temporal aspects have not been adequately considered. The last two decades have witnessed great advances in computer technologies, digital mapping, and geographic information systems (GIS), including the development of temporal GIS technologies that are capable of supporting analyses of data that have both a spatial context and a time dimension. These advances offer us a new opportunity to examine the land use and transportation co-evolution at a larger scale and at a more detailed level. With understanding gained through such studies, we will be able to better account for land use and transportation interactions in travel demand models and land use allocation models, enabling us to make better decisions about transportation investments.
The project is aimed at answering questions concerning land use and transportation interactions, such as:
- How do land developments change travel patterns in short and long terms?
- How does transportation system respond to new land development? When improvements to transportation system are triggered by land use developments? What strategies are employed in terms of transportation improvements such as short term or long term investments?
- What types of land development projects occur around different types of transportation projects? What is the spatial pattern of land developments? Do they tend to cluster around new transportation project sites?
- What is the temporal pattern of land developments? Is the rate of land development constrained by accessibility? How fast do land developments respond to improvement of accessibility, or how far do land developments lag behind transportation improvement projects?
- How stable is land use patterns temporally or spatially?
- Under what conditions do land use changes slow down or stop? When needed transportation improvements are not or cannot be made, does land use pattern change accordingly?
The objectives of the project may be stated as follows:
- To gain a better understanding of land use and transportation interaction, which will be the foundation for future attempts to improve land use forecast and travel demand models;
- To quantify certain land use and transportation interactions that can be incorporated into ULAM and FSUTMS models;
- To develop a spatiotemporal GIS data model that is becoming more and more critical for the purposes of transportation planning, infrastructure management, and for ITS applications; and
- To develop useful GIS databases that may be used by the FDOT and the general public for similar or other purposes. The new GIS databases will be provided to University of Florida GeoPlan Center for possible inclusion in the FGDL.