Publication Detail

A Multi-Scale and Context Sensitive State-Wide Environmental Mitigation Planning Tool for Transportation Projects in California


Research Report

Urban Land Use and Transportation Center

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Suggested Citation:
Thorne, James H., Evan H. Girvetz, Michael McCoy (2007) A Multi-Scale and Context Sensitive State-Wide Environmental Mitigation Planning Tool for Transportation Projects in California. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-07-39

The University of California Information Center for the Environment (ICE) and the California Department of Transportation (Caltrans) are developing a GIS-based analytical framework to improve the effectiveness of biological mitigation throughout California. Goals include incorporating the best available sets of mapped natural resource data into the early project planning and preliminary environmental assessments for single and multiple projects. Incorporation of these data will facilitate early and more strategic identification of mitigation requirements and op¬portunities, for both single-project and regional mitigation efforts.

The cost of delays and over-runs due to late and fragmented project-by-project environmental planning and mitigation in California is estimated at $75 million per year. Developing systematic GIS-based decision-support tools to identify important species and habitats, both those impacted directly by Caltrans activities and those that might contribute to effective mitigation in the same locale or watershed will permit Caltrans, counties, and environmental regulators to incorporate the results of biological impact assessments earlier in the planning process, and identify opportunities mitigating the combined biological impacts of many projects in a given area. By building upon previous efforts and using tools known to be effective for integrated analyses, this project will help Caltrans improve planning results, decrease costs, improve project delivery schedules and provide greater environmental protection in the long-term.

To accomplish these goals, Geographic Information Systems (GIS) analysis and conservation planning principles are being applied to develop multi-scale longrange (10-year) mitigation need forecasts for each Caltrans district, county, and watershed in the State of California. These will be used to determine the cumulative mitigation needs for early biological mitigation planning of multiple projects in a given area. Available statewide biological data have been integrated into a database that can be queried by Caltrans district, county, or any of six levels of watershed classification. For a queried geographic area, the database returns the biological resources expected to exist in the area based on the available data, as well as the potential impacts to these resources from Caltrans projects that are currently funded to be constructed in the area over the next 10 years. The type of project programmed to occur was then used to estimate the impact zone of each project (e.g. road repaving, road widening, new road, etc.). Then, by querying the database for a given geographic region, the area, habitats and species potentially affected by cumulative biological impacts from all programmed highway projects in that region can be estimated. From this, estimates of area and types of lands that would need to be acquired for mitigation can be determined.

This project provides a framework for analyzing and estimating biological mitigation needs that could be generalized for use in transportation planning in other geographic areas, as well as for other types of planning. The database schema developed here could easily be adapted to analyze the potential impacts and mitigation needs for urban growth planning efforts, and other development projects with biological impacts that require biological mitigation planning. Overall, by integrating available data into a useful database format, this project has developed a system for assessing long-term biological mitigation needs that will assist in the implementation of early biological mitigation planning