Combining State Route and Local Road Linear Referencing System Information

The Wisconsin Department of Transportation maintains two separate geographic information system databases: one for state roads and one for local roads. Both databases employ linear referencing system (LRS) theory to manage and locate information. Combining data from state and local roads into one system is desirable for the purpose of data management and analysis. This paper's approach combines information from the state route LRS (link ID and offset distance) with information from the local road LRS (node ID) to produce a table that can be employed to transfer data between the systems. A computer program was developed to use this table, along with existing tables in each LRS, to move information from the state route system to the local road system. Quality assurance and quality control techniques are presented along with a long-term implementation approach; both help to update the table bridging these two systems. The approach described does not interfere with the current operation of either system; therefore, no interruption of business practice will occur as this data transfer approach is deployed. Although this approach can transfer any LRS data, a case study of crash data for Dane County, Wisconsin, is used to demonstrate and test the approach. In the case study, crash points on the state routes are combined with local road crashes to produce a complete data set of crashes within the county.