To help improve harbor safety in the face of increasing shipping volume and vessel sites, an experimental Vessel Traffic System has been designed, fabricated, and installed in San Francisco Harbor. The Traffic Analysis and Display portion of the system uses computer generated synthetic map and text displays to provide an interactive system for up to three operators. A series of services has been designed which enable the operators to obtain radar contact information and to enter, modify, and recall text information through a series of simple keyboard actions.In addition to the interactive working displays, 4 supporting displays have been provided for designated map segments of the harbor, along with two alpha numeric displays for summary text information. A set of symbols has been developed to allow quick recognition of the vessel traffic situation by the operators.A control computer connected to three interactive display computers and five passive display units provides complete radar contact processing and display, as well as quick respond to independent operator requests for information or services. The operators can put vessels into any one of three basic categories which allows them to keep the vessels sorted and easily follow the progress of the important ones through the harbor.A background program supplements the operator actions by looking for and reporting specific trouble situations, such as collision warnings, allowing an operator to concentrate on a particular situation without fear of missing a major problem elsewhere in the harbor.