A MODEL FOR CREATING INTERACTIVE GEOLOGIC MAPS, TO BE USED FOR THE DESIGN OF TRANSPORTATION SYSTEMS

Knowledge of surface and subsurface geology is fundamental to the planning and development of new or modified transportation systems, as well as other land use issues. Toward this end, we have compiled GIS databases for two locales. The first consists of critical geologic, cartographic, environmental, and cultural data along a transportation corridor in southern Rhode Island that includes spatially defined themes, largely obtained from the RI GIS database, which can be overlaid on-screen or in printed format to show geographic distribution of the diverse types of data. The second is centered about Providence. A key feature of both is the inclusion of subsurface information from bore holes in the region, the result of a cooperative program with RIDOT and others that provided access to most boring logs. We have developed a protocol for the inclusion of borehole data that permits the conversion of disparate types of logs into an internally consistent data set, that may be used to construct cross sections, isopach maps of sand and gravel thickness, etc.

Geologic data include bedrock geology, surface outcrop, surficial deposits, soil type, topographic and orthophotographic base maps, and location of ground-water wells and boreholes. Subsurface geologic and hydrologic data associated with the site-specific wells and boreholes are an integral component of the database including land-surface elevation, depth to water table, depth to bedrock, and material properties, all invaluable for transportation planning. This interactive database is available in two user-friendly formats:1) CD-ROM with an attached simplified viewer (Explorer); and 2) a website in which the database can be queried and downloaded in a variety of GIS formats. The database is structured to easily incorporate new data as it is acquired, thus providing condensed, easily accessed information essential to transportation planning. In addition to transportation applications, the spatial data is of interest to a broader audience, including state agencies dealing with environmental management and planning issues, town planners, conservation and environmental groups, and concerned citizens.