The first GPS based vessel traffic service system for an American inland waterway

The paper describes the design and the development of an advanced vessel traffic service system (VTS) that was demonstrated in 1994 on the section of the Saint Lawrence Seaway under control of the Saint Lawrence Seaway Development Corporation (SLSDC). Vessel traffic service on the Saint Lawrence Seaway has undergone little change since the Seaway opened in 1959. The current VTS system depends primarily on voice reports from ship masters and pilots who make VHF calls to control centers at assigned, but very approximate, call-in-points (CIP) along the Seaway. The location accuracy of a vessel, using these procedures, is about one to two miles. It is difficult to improve safety and to increase the efficiency of the Seaway system with the present traffic services accuracy limitations, and expeditious use of the locks suffers due to erroneous position reporting. In 1991, SLSDC enlisted the aid of the Volpe National Transportation Systems Center to design and to develop a VTS system using the Global Positioning System (GPS). The VTS system is an automatic dependence surveillance system that uses one-way communications to provide the control center at the Eisenhower Lock with vessel positions at assigned update rates. While the VTS system utilizes mostly commercially available off-the-shelf components, innovative designs were required to produce a shipboard unit that was lightweight, relatively inexpensive, and technically versatile.