ROADrule USATONS Weems and Plath ROADrule USATONS is a quick reference tool that identifies the most common U.S. aids to navigation, rules of the road, and maneuvering and warning signals for U.S. waters. ROADrule takes a large amount of complex information and makes it easy to understand. Whether in a classroom or at the helm, critical decisions can be made quickly and with confidence with the aide of ROADrule. Its design is similar to a slide-rule. (Versions of ROADRule are also available for European Inland Canals and International Waters). Displays 38 navigation aid definitions Displays 12 Rules of the Road Identifies bridge lighting and Intracoastal Waterway markings The various buoyage markers are drawn in color to match the chart symbol. Actual view of maritime buoyage systems with corresponding chart symbols. Magnifying lens for clear readability of definitions Durable two-sided black PVC construction. Stored in a vinyl sleeve and fits nicely in a chart table.