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Each U. S. port and waterway has its own geography, special hazards, and degree of congestion, but only two—San Francisco harbor and Puget Sound—boast continuously manned Vessel Traffic Centers. The San Francisco center, above, which monitors information obtained from two high-resolution radars, is a forerunner for a number of similar systems with which the Coast Guard hopes to administer the ounce of prevention that will save tons of shipping presently lost to accidents that might have been prevented.
A vessel traffic system (VTS) is an integrated system encompassing the technologies, equipment, and people employed to coordinate vessel movements in or approaching a port or waterway. It may be simply a regulated navigation area using stop-and-go traffic lights; or it might incorporate positive control features with high resolution, automated, surveillance and display equipment. Either way, the objective of such systems is to reduce the probability of ship collisions and groundings, and damage to the environment.
It took the United States some 20 years to achieve general acceptance of systems of marine traffic control. A shore-based harbor radar service was established in 1949 by Jacobsen Pilot Service, Inc. in Long Beach, California, and has been operated continuously by them
44 U. S. Naval Institute Proceedings, December 1974
ever since. This was just one year after the first harbor radar installation in the port of Liverpool, England. The pilots employed by the city of Los Angeles followed with their own harbor radar in 1951. The radars in Long Beach and Los Angeles were installed in the pilot dispatch offices and used by the pilots for their own purposes. They have not been continuously manned and do not provide for overall traffic management in these ports, nor were they ever intended to do so.
In 1951, a harbor radar demonstration, patterned after the systems in Liverpool and Long Beach, was initiated and funded by the Port of New York Authority. The potential benefit of providing harbor radar services was demonstrated, but funding, management, and liability problems for a permanent system were not resolved. The demonstration was terminated in 1952.
From 1962 to 1965, a second demonstration project was conducted in New York by the U. S. Coast Guard. This project, known as RATAN (Radio and Television Aid to Navigation), featured a television picture of a standard radar PPI scope. Technical problems led to a termination of this demonstration, although the concept is still under consideration for further research and development.
In November 1968, the Coast Guard began planning for a more extensive, experimental, harbor advisory radar project. San Francisco was selected as the test site for several reasons:
► The bay had an established voluntary vessel movement reporting system and an existing, well developed, commercial communications system with ready access to shipping.
► The frequency of fog would permit a more complete evaluation of the worth of the system in periods of low visibility.
► Traffic density was not so high that the experiment would prove to be unduly complex in data collection and analysis.
► The bay complex presented several traffic patterns, which would allow the experience gained to be extrapolated to other ports.
The Coast Guard began operating the San Francisco Harbor Advisory Radar (HAR) Project on an experimental basis in January 1970. The intent was to proceed rather deliberately with the HAR equipment before trying to develop any fully operational systems. The collision between two tankers beneath the Golden Gate Bridge on 18 January 1971, with the discharge of 800,000 gallons of oil into San Francisco Bay, greatly accelerated plans. It also intensified congressional action on pending legislation to provide additional regulatory authority needed by the Coast Guard to make the federal port safety program more effective. This legisla
tion, known as the Ports and Waterways Safety Act of 1972, contains very specific provisions for the Coast Guard to establish, operate, and maintain vessel traffic services and systems for ports, harbors, and other waters subject to congested vessel traffic.
San Francisco VTS. On 22 August 1972, the San Francisco Vessel Traffic System became operational. In March 1973 a voluntary traffic separation scheme became effective and in May 1973 the traffic center was moved from its temporary site to a newly constructed building atop Yerba Buena Island in the central harbor. Two high-resolution, high-performance radar systems especially designed for marine traffic surveillance and control provide radar coverage of the harbor and approaches. One is located at the new center, the other on the rocky coast seaward of the Golden Gate Bridge. Improved communication and remote control links were placed into service at that time. The system is now being expanded to include a vessel movement reporting system for the delta region up to Sacramento and Stockton. Regulations are under development which include provisions for mandatory participation.
The research and development efforts in San Francisco are continuing side-by-side with the operational system on a not-to-interfere basis. In July 1973 testing began on experimental synthetic displays, with computerized processing of the video information. The traffic controller identifies vessels by correlating radio reports with the radar targets. The computer then maintains the track and identification of selected contacts. The computer output is displayed on five television type screens. Four provide sectorized coverage of the entire harbor. The fifth is a working display subject to operator manipulation of target data.
Use of these synthetic displays, as opposed to the PPI presentation only, provides the controller with faster, more complete data retrieval, and much more flexibility in manipulating data. Provisions are included for target capture and identification, automatic tracking, and automatic collision and grounding alerts.
Puget Sound VTS. The tanker collision in San Francisco Harbor also provided impetus for development of a Vessel Traffic System in Puget Sound, the waterway approach to Seattle and Tacoma, Washington. Puget Sound will soon realize an increase in tanker traffic bringing oil from the southern terminus of the Trans- Alaska pipeline to refineries in the area. Although planned as an operational system, it may also be considered a test site. The geographical configuration required the development of procedures somewhat different from those used in San Francisco Harbor.
The Puget Sound VTS was commissioned on 25 September 1972. The major components of the system are a Traffic Separation Scheme (TSS), a Vessel Move-
Collisions and Groundings: Preventing the Preventable 45
In Puget Sound's Vessel Traffic Center, which will soon realize an increase in tanker traffic bringing oil from the southern terminus of the Trans-Alaska pipeline to refineries in the Northwest, watchstanders receive radio reports of vessel movements from masters and relay reports from other vessels in the vicinity.
ment Reporting System (VMRS) and a continuously manned Vessel Traffic Center (VTC). Traffic lanes 1,000 yards in width are divided by a 500-yard separation zone. The centerline of the separation zone is marked by 17 mid-channel buoys. Masters report their own vessels’ movement and other navigational safety information, to the VTC via VHF-FM radio on channel 13, the vessel bridge-to-bridge radiotelephone frequency. They, in turn, receive reports on other vessel movements and navigational safety information from the center.
At present, the Puget Sound VTS relies on voluntary compliance; however, regulations requiring participation will become effective in the near future. Limited radar surveillance of the more congested traffic areas is being added in 1974, and expansion of the traffic separation scheme into the Strait of Juan de Fuca is being pursued in cooperation with Canada.
Other Developments. The Houston Ship Channel between Galveston and Houston, Texas, is the site of the Coast Guard’s next major vessel traffic system. Planning for the Houston/Galveston system is complete and construction has begun. Plans call for development in two phases. Phase I, with an operational date of November 1974, includes a VMRS from the entrance at Galveston to the Houston turning basin; a complete communications net; low light level, closed circuit TV; and a manned center in Houston. Phase II will add radar surveillance of the seaward approach to Galveston, Bolivar Roads and the lower Galveston Bay.
Two other major systems are in advanced planning stages. One is for New York harbor and approaches, including Long Island Sound. The other is for the lower Mississippi River, including both New Orleans and Baton Rouge. The Coast Guard has also completed preliminary planning for a system in Valdez, Alaska. Valdez will be the southern terminal for the pipeline from the Prudhoe Bay oil discovery on the northern slope of Alaska.
The numerous ports and waterways of the United States are visited by almost every size and type of vessel currently in use in the world. These vessels transport | thousands of different types of cargo. Many of these
cargoes when spilled are hazardous or polluting. The size of bulk carriers continues to increase. Operating speeds are going up. The potential for major marine disasters exists.
According to U. S. Coast Guard marine casualty statistics, the number of collisions and groundings in U. S. waters rose from 1,342 cases in fiscal year 1968 to 1,460 in fiscal year 1971. The average annual "reported” losses to vessels, cargo, and property from these casualties exceeds $40 million. A recent study of the Coast Guard marine casualty reports suggests that owing to unreported casualties and underestimates of the dollar losses for those casualties that are reported, the actual annual dollar losses probably exceed five times that amount or $200 million per year. The annual loss of lives and number of serious injuries during this same period averaged 56 and 52 respectively.
In calendar years 1971 and 1972, the two years for which complete data on pollution was available, there was a total of 274 polluting incidents caused by collisions and groundings which spilled an annual average of 228 million gallons of pollutants into U. S. Waters.
Statistics indicate that waterborne commerce in the United States will increase substantially between now and 1980, and the carriage of hazardous and potentially polluting cargo will be a significant part of this growth. Thus, the forecast for the future shows increased waterway congestion and greater potential risk of traffic accidents. Historical casualty data and the future outlook for waterborne commerce indicate a need for improved marine traffic safety in U. S. ports and waterways. Vessel traffic systems can make significant contributions to this effort. Some basic concepts for system design and development are discussed in the following pages.
Ports and waterways do not come in standard sizes or shapes. Each has its own geography, special hazards and degree of congestion. Some extend for only a few miles. Others cover several hundred miles. Vessel traffic systems must be tailored to the specific areas serviced. However, to be successful, any system must provide the traffic controller with some common features, such as:
► an information display of the identity, position, course,
and speed of all vessels on plot in his area of jurisdiction, and information relating to the physical environment. This information display must be presented in a format that is readily assimilated by the controller, and maintained current with minimum effort.
► a means to rapidly compare vessel traffic movements with established standards, and to immediately recognize those movements that are not within these limits. The tolerances of the established standards must be directly related to the characteristics and capabilities of the vessels operating within the system and to the measuring capability of the system.
► the capability to rapidly assess significant changes in relationships or circumstances in order to spot potentially dangerous situations. Corrective action can then be taken.
As in all systems which employ humans in a functional role, the development of the system must consider the informational requirements of the humans as the primary factor. The VTS must be directly responsive to the information requirements of both the traffic controller and the vessel operator. The controller requires the position, identity, and intent of all participating vessels in his area of jurisdiction including information relative to the physical environment. The vessel operator needs information concerning the circumstances and conditions in the adjacent environment, as well as his own position.
For system design, the above concepts must be translated into a framework for practical application. To do this, a workable number of system components have been identified. These are:
► Regulated Navigation Area. This term encompasses such things as one-way traffic areas, restricted passing zones, and speed limitations. It is the minimum form of regulation envisioned.
► Traffic Separation Scheme (TSS). This component is made up of a network of traffic separation lines or zones, traffic lanes and precautionary areas designed to coordinate the flow of traffic within a VTS area. A TSS can be voluntary for some vessels and mandatory for others as it is not envisioned that all vessels will be required to use it. However, once a vessel chooses to use the TSS it must comply with the established rules.
► Vessel Movement Reporting System (VMRS). This component requires communication equipment and establishes reporting procedures. Upon entering the VMRS area a vessel identifies itself and reports its position and intended movement, as well as other pertinent data, to the VTC. The VTC records the information and makes it available to other participants.
► Basic Electronic Surveillance. The addition of electronic surveillance equipment such as radar or TV allows the
VTC to play a more active role in the sectors covered. Vessels can be identified and their positions fixed within the accuracy of the equipment used. This provides the VTC with the capability to monitor vessel positions in traffic lanes including both lateral position and fore and aft separation. The VTC will have increased capability for directing vessel movements. This increased control may be necessary for such reasons as adverse weather, traffic congestion or special routing of vessels carrying dangerous cargo.
► Automated Advanced Surveillance. This component consists of specially designed surveillance equipment with automated information display. It adds the capability for positive vessel identification, and continuous tracking with course and speed indicators. An active role by the VTC is implied. This component will enable the system to handle a larger number of vessels under mandatory participation. Reduced manning may be a tradeoff for higher initial cost.
The above listed components, from simple to very sophisticated in terms of hardware, serve as the building blocks of a VTS. They can be combined to form subsystems satisfying the needs of specific geographic sectors of a port or waterway. The combination of subsystems within the VTS area of operation, under control of a single vessel traffic center, makes up the total system. The sophistication of these combinations of components and subsystems will be determined by the degree of traffic management deemed necessary for the safe movement of vessels in the given port or waterway.
In general terms, the three degrees of traffic management or control envisioned are the coordination of vessel traffic by (1) physical arrangements such as a traffic separation scheme without manned traffic centers; (2) disseminating advice in the form of navigational, weather, and vessel movement information. (Manned vessel traffic centers are required either continuously or intermittently as the situation demands); and (3) positive control of vessel movements from a continuously manned vessel traffic center. Navigation responsibilities remain with the vessel, but the center will direct vessel movements as necessary to prevent collisions and groundings.
The Coast Guard recently completed a detailed casualty analysis of major ports and waterways in the United States. The ports were selected on the basis of tonnage of cargo handled, number of vessel transits, and number of vessels involved in collisions and groundings over a four-year period, Fiscal Years 1969-72. Over 1,800 casualty cases involving 3,921 vessels were analyzed. The circumstances of each casualty were examined to determine which accidents might have been prevented by a VTS and by what level of VTS. Estimates of expected future damages caused by collisions and ground-
Collisions and Groundings: Preventing the Preventable 47
Figure 1.
definition of Levels:
Lq—Bridge-to-Bridge Radiotelephone Lj —Rcgvilatcd Navigation Area I^—Traffic Separation Scheme L3—Vessel Movement Reporting System L4—Basic Electronic Surveillance Ls—Automatcd Advanced Surveillance
2An accident is defined as any collision or grounding incident. The total number of vessels involved in all accidents was 3.921. The total number of vessels involved in collisions between two moving vessels was 1,344.
3The percent reduction in accidents was computed using the total number of vessels in accidents.
ings without VTS were tabulated and estimates of damage reductions with VTS in effect were calculated. The ports were then ranked according to need for VTS services.
In addition to a port ranking, this analysis provided an estimate of system effectiveness versus level of VTS. The results are shown in figure 1. The data base for the analysis covered a period prior to implementation of the Vessel Bridge-to-Bridge Radiotelephone Regulations (B-to-B) on 1 January 1973. This required that an adjustment be made to take into account the expected effectiveness of those regulations. Shipboard VHF radiotelephone equipment has been used on a voluntary basis in most major U. S. ports and waterways to varying degrees for many years. The new law requiring VHF-FM capability, and a continuous guard on a dedicated frequency by all vessels should make such usage | a more dependable factor. As can be seen in figure 1
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it is estimated that increased use of B-to-B should eliminate about 22% of the collisions between two moving vessels, in meeting, crossing, or overtaking situations. This is a reduction of 60 collisions per year in U. S. waters. Overall B-to-B should eliminate about 9% of all collisions and groundings or about 126 per year.
In general, after deducting for the expected effect of B-to-B, the analysis indicated that continuously manned vessel traffic systems can be expected to result in a 30 to 40% decrease in accidents between two moving vessels and a 15 to 25% decrease in all collisions and groundings. Arriving at these percentages involved a good deal of subjective judgment. The criteria used in making the judgments were such that reasonably similar results were obtained by different people evaluating a given casualty record.
A detailed statement of requirements for vessel traffic systems is now being prepared by the U. S. Coast Guard. This will include requirements for communications, surveillance, information display, and computer interface. It will be based on the concepts set forth in this paper, experience gained operating two active systems, and an active VTS research and development program.
Because other countries have more experience than the United States in many aspects of vessel traffic system design and operation, U. S. Coast Guard managers and engineers have visited the systems in Canada, Germany, the Netherlands, France, and Japan. Formal research exchange meetings have been held with representatives of many countries. However, a more universal effort to coordinate international developments in marine traffic management is needed. Terminology, shipboard equipment, radio frequencies, and communication procedures should be standardized insofar as is practicable. Those involved in the design and operation of marine traffic management systems should work together toward this common goal.
Captain Hill graduated from the U. S. Coast Guard Academy in 1953. He served one year as a deck officer. The next four years were spent in engineering afloat, the last two as chief engineer on a sea-going tug in Portland, Oregon. He then spent three years at graduate school, graduating in 1961 with a master’s degree in naval architecture and marine engineering and a professional degree as naval engineer from Massachusetts Institute of Technology. Two years as chief engineer on a high endurance cutter stationed in Alameda, California, were followed by eight and one-half years in merchant marine technical duties, the last two and one-half years as Chief of the Merchant Marine Technical Branch in New Orleans. In January 1972 he was transferred to Coast Guard Headquarters to plan and begin implementing a national plan for vessel traffic control. Captain Hill assumed his present position as Chief, Boating Education Division in the Office of Boating Safety in March 1974.