Transportation framework data includes six components: roads, trails, railroads, waterways, airports/ports, and bridges/tunnels. Of these, roads are the most widely used to support GIS and have the highest priority. As critical transportation infrastructure, often roads serve as a base layer or as the primary reference for other map features. Depending upon scale, a variety of road types may be displayed, from interstates to city streets. Road data are challenging to maintain, especially in rapidly growing areas, and public and private organizations may both be involved in monitoring changes. Data producers strive to maintain positionally accurate centerlines and attributes, especially road names and address ranges, but completeness of the data often is inversely proportional to the rate of growth in a given area.
The strategic plan for addressing this state data need is being developed by a transportation data workgroup with assistance from the Strategic Plan Committee of the Governor's Council on Geographic Information.
Tied inextricably to the economy and land use, transportation information is critical to private and public enterprise. Typical uses include: enhanced-911 dispatch and routing, school bus routing, commercial routing and delivery, pavement inventory and planning, land records integration, bikeways mapping, infrastructure planning and management, transit planning and routing, and network analysis.
Many transit and transportation departments use geographic street databases as the foundation for data collection, data integration, and analysis within GIS applications. Road characteristics, such as speed limit, pavement type, and activities, such bus and snowplow routes, can be linked to features directly or through a linear referencing system. Accurate address ranges enable automated geocoding of activities and events. For many organizations, the primary use of road datasets is as a reference layer for maps.
Several organizations in Minnesota maintain road datasets for a variety of business needs. Nationwide databases are available from the Census Bureau and USGS, but are of limited use due to their coarse resolution. User needs are more likely to be met by other databases:
Pre-Assembled Data. Some rural areas support GIS applications with vendor-specific packages of street networks, which are often spatially imprecise and incomplete. They remedy this with custom improvements generated from local knowledge; this is another potential source of updates in any transportation data sharing efforts.
Work on the MSDI Data Plan for roads is planned to be completed by the summer of 2005.
No solid information on costs and financing is currently available. Mn/DOT’s LDM project will likely meet the needs of many, but not all users. Integrating TLG data and local datasets with the LDM may pose a significant increase in maintenance costs for those data producers. MetroGIS is working to estimate these cost for the Twin Cities area.
To learn more about the strategic plan for meeting transportation data needs within Minnesota, contact the workgroup chair.