Introduction
The Environmental Screening Analysis Tool (ESAT) is a software tool being developed to help transportation planners identify potential impacts of proposed road corridors. Both physical and social-cultural impacts of the road can be examined. The tool makes use of standard GIS datasets and provides a user-friendly interface with several generic preset analyses to semi-automate the initial screening of a new road project. Users also have the option to customize the settings of each of the specific analyses.
The purpose of providing a tool for environmental screening is to help planners identify early on in the planning process the major issues that may arise from a new transportation investment. Once the main issues are identified, the appropriate stakeholders, such as resource agencies, local government officials, and community groups, can be consulted, before additional time and resources are invested into the project. Building consensus on the fundamental issues early on in the planning process will streamline project development and implementation, and minimize conflicts when it comes to permitting and winning public approval. ESAT is also a useful tool for quickly identifying the advantages and disadvantages of multiple alignment options. |
ESAT can help planners
quickly visualize potential physical
impacts such as on wetlands |
Although ESAT generates numeric indicators and spatial outputs which can support other studies, ESAT is not intended to replace traditional, more rigorous methods of environmental impact evaluation. Its main purpose is to identify fatal flaws or potentially significant impacts and prioritize where additional analysis will be required. The questions that can be examined by ESAT depend on the nature of the available data. Both environmental impacts as well as socio-economic impacts and jurisdictional issues can be studied if appropriate data is available. Any type of question whose answer depends in part on a geographic relationship with the proposed corridor may potentially be integrated into ESAT.
On the flip side of this flexibility, one must remember that the quality of results produced by ESAT will only be as accurate and up-to-date as the data used. For example, statewide habitat coverage digitized at 1:100,000 may be only accurate to within 500 feet. This may be fine for large-scale analyses, but may result in a high margin of error when trying to determine how much habitat will be impacted by a 220-foot wide corridor. Likewise, a census coverage that is ten years out of date will likely underestimate any demographic measures for community impact assessment.
In addition to making the early screening process semi-automated, ESAT is also extremely useful for sharing data and impact methodology. Many of the analyses that come packaged with ESAT make use of the Florida Geographic Data Library (FGDL) that is available for every county in Florida. Users can tap into this rich compilation of spatial data or supplement it with their own data. Users can also develop and share analyses with each other. For example, a habitat specialist can define a test to identify potential impact on strategic habitat, post the test to the central online database, where it can then be shared with any other ESAT user in the state that has access to the same data.
Application Features
The ESAT application offers a number of tools to planners for road screening:
multiple corridor analyses - more than one alignment option can be analyzed at once and the results will be presented side by side. ready-made outputs - the application generates evaluation summaries in MS Word and HTML format. The reports include plain-English explanations of each test result, maps customized to show the area of impact, and summary tables. These reports can then be further edited with MS Word or an HTML editor, and shared with other stakeholders either electronically or in hard copy. user-friendly interface - both automated evaluation reports and new spatial layers can be created with an easy to use 'Evaluation Wizard'. New evaluation criteria and tests can be entered with easy-to-use data entry forms that do not require any specialized GIS background. customization of analyses - users may edit new parameter values for each test, or develop new tests using one of the preset spatial analyses. impact area options - users may select which geographic area should be used as the impact area for each analysis. The choices are the corridor only, the corridor plus an additional buffer zone, or an impact region defined specifically for the corridor. sharing evaluation methodology - the application allows users to create sets of evaluation questions/tests that can then be shared with other users over the internet. This will allow, for example, one planning office or resource agency to share the tests developed for a particular project with similar projects in other counties. multiple data sources - the application can use any spatial data in standard GIS formats, in addition to the many data layers available from the Florida Geographic Data Library CD ROM series. This means that almost any impact question, if it can be evaluated by one of the preset analyses (see below), can be integrated into the screening tool as long as there is data for it. on screen road digitizing - a utility is provided to "digitize" a new road with the mouse. Once the center line is drawn, the user can specify a buffer width for the corridor. online help - the application comes with a comprehensive online help system (under development)
Software Required
ESAT is an extension for ArcView GIS, version 3.1 or 3.2. If cell-based Grid data is to be used, then the ArcView Spatial Analyst extension is also needed. MS Word (either '97 or 2000) is also required to create summary reports, and MS Access (97 or 2000) is used for data entry of tests.
User Knowledge Required
The "Evaluation Wizard" does not require any familiarity with GIS software and can be used by virtually all users. However adjusting the parameters of tests, creating new tests, and problem solving output issues will require some familiarity with GIS data and GIS concepts. However users do not need to know the intricacies of doing intersections, clips, etc. with ArcView, because the Evaluation Wizard does all of that. Any person who has completed an introductory ArcView class and FGDL class should be able to use all of the features of the application, including defining new tests.
The online help system should provide sufficient information on adjusting tests parameters and output options to produce the desired results. In addition training will be developed for users on customizing ESAT for new data and new tests.
Data
ESAT source data must be in ESRI shapefile or Grid format. If needed, ArcView can be used to convert ArcInfo coverages to shapefiles before using ESAT. Raster data which is used only as a backdrop (i.e., an aerial photo) must be in a format that can be read by ArcView, such as IMG, TIF, or JPEG. Users can develop their own data layers, or use packaged data from the Florida Geographic Data Library CD ROM series. For more information about FGDL, see http://www.geoplan.ufl.edu.
Preset Spatial Analyses
To provide maximum flexibility, ESAT comes equipped with several generic preset spatial analyses that can be used with different data layers and different parameters to answer a wide array of evaluation questions. Once entered, these tests will appear on the evaluation wizard and can be run for any corridor alternative being considered. The preset analyses currently available include:
area of intersection - This test will calculate the amount of area of intersection of the corridor impact area and the comparison theme, such as a wetlands theme. The corridor impact area can be the corridor itself, the corridor plus an additional buffer, or a polygon region defined specifically for the corridor. This test is appropriate for any impact question which can be answered using polygon data. Examples include impact on wetland areas, impact on proposed or existing conservation areas, etc. The Evaluation Wizard will calculate the total area of intersection, and show a map of the area. There are actually two preset analyses for area of intersection, one for vector layers and one for grid data. proximity to points - this test will find all points from the comparison theme that fall with the corridor impact area. The Evaluation Wizard will count up the number of points and show a map of the points. This test is appropriate for impact questions that can be answered using point data. This includes impact on public facilities, such as school and churches, or the proximity to known locations of rare and endangered species. map only - this is not a really a "test" in the sense that it does not come up with a number which is a measure of impact. However this test will load the correct spatial data and present the user with a map. This is appropriate for questions that are not easily quantified or are not GIS questions. For example, "does the corridor impact community cohesion" is not something you can easily attach a number to, but an analyst can quickly decide if this is going to be a big issue by looking a map of the corridor overlaid with neighborhoods in the project area.
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