Computer modeling software is also used to plan plow routes for each county. Data on equipment capabilities, personnel resources, facility locations and highway types is entered into the system. Highway layouts and the locations of available plows and salt stores are then examined, to determine the most effective routes for snow plows and salt spreading equipment. Global Positioning System (GPS) devices were also installed on ODOT vehicles, to help monitor the locations of ODOT equipment. This allows the department to track the exact location of snow removal equipment and determine which routes have already been serviced.