Blue Earth County Develops GIS-Based Highway Information System
by Al Forsberg
Counties have available a large store of information on their road and bridge systems compiled for various local, state, and federal purposes. Database information includes vehicle crashes, traffic volume, road geometrics, reconstruction costs, weight restrictions, pavement condition, construction history, etc. The challenge has been to use this information as a basis for decisions on investing scarce road and bridge construction and maintenance funds.
A large database, a map, and a need to link and query this information-theses are the ingredients for Geographic Information Systems (GIS). The Blue Earth County database consists of Carte Graphics County Highway System software. The map consists of the Mn/DOT digitized county highway map with each road divided into sections corresponding to the State Aid needs segments. The county used Map Info, a relatively economical PC software, as the GIS link between the database and map.
This GIS allows the county to ask questions and get answers in both lists and shown on a map. For instance, which road segments have a high vehicle crash rate, poor pavement conditions, and are weight-restricted? The GIS can promptly provide a list and show on a map all segments meeting these criteria.
The county is currently updating and completing the database. The system has been the basis for its recently developed long-term transportation plan. It is also being used for updating the five-year capital improvement plan. The system does not make decisions for your county; however, by organizing the available information and allowing you to ask questions easily, it can be a big help in making them.
--Forsberg is Blue Earth County's highway engineer.