LinkerAT addresses the problem of relating the Regional Integrated Transportation Information System (RITIS)/Traffic Message Channel (TMC) network and the All Roads Network on Linear Referenced Data (ARNOLD). These network datasets describe roads and connections for all 50 states and the District of Columbia. The RITIS/TMC network is used to segment and report real-time vehicle speed data. ARNOLD is a specification developed by FHWA to inventory each state’s roadway network in terms of road configuration and condition by segment. ARNOLD serves as the mapping foundation of the Highway Performance Monitoring System (HPMS). Due to the difference in the intended use and purpose of the RITIS/TMC network and ARNOLD, segmentation of the networks and representation of network features vary significantly. 

LinkerAT uses a combination of geographic and thematic cross referencing to identify how the ARNOLD network represents parallel elements in the RITIS/TMC network. To support LinkerAT and provide a fully open-source software implementation, the networks are input to the program in Geographic JavaScript Object Notation (GeoJSON) format, which is the standard format used for LinkerAT. LinkerAT uses a series of algorithms to identify corresponding elements in the source (RITIS/TMC) and target (ARNOLD) networks. The process involves a series of steps or phases executed to maximize the likelihood of a solution. Much of the process is automated with the program running in the background and tabulating a solution set. As the program runs, it “learns” more about the network and how elements can be cross-referenced, so multiple program runs are executed sequentially to effectively apply this new knowledge. The LinkerAT Guide presents more details on the methodology.

The LinkerAT program code, software tool, documentation, and example datasets for use, are public domain and will be available for download for free on the NCHRP 08-119 page on TRB’s website at LinkerAT includes all necessary libraries and support to run the program on a standard Windows computer. LinkerAT requires no special libraries or proprietary software. 

Implementing LinkerAT for a given state requires both knowledge of principles of geographic information systems (GIS) and associated tools and proficiency in JavaScript software development to customize the LinkerAT tool for a particular state.