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Shiphandling Simulation: Application to Waterway Design Shiphandling Simulation
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Shiphandling Simulation: Application to Waterway Design This page in the original is blank.
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Shiphandling Simulation: Application to Waterway Design 1 Introduction WATERWAY MODERNIZATION The nation's ports and 28,000 miles of navigable waterways authorized for improvement under federal programs are vital to national, regional, and local transportation and economies. They provide a critical intermodal link to the global economy while also serving as local and regional employment centers. Over 30 percent of the nation's domestic intercity freight trade and 99 percent of overseas trade by weight (74 percent by volume) pass through this system as waterborne commerce. Although variable from year to year, the flow of cargoes through U.S. ports hit 2.09 billion tons in 1988 (U.S. Maritime Administration, 1990). However, existing ports and waterways do not adequately accommodate the most modern ships in terms of efficiency, safety, and cargo handling capabilities. Thus, there is interest nationwide for modernization of ports and waterways systems to accommodate modern ships and maintain competitive advantage in regional and international trades (Frankel, 1989; Journal of Commerce, 1991a; Kagan, 1990; U.S. Maritime Administration, 1990). At the same time, the escalating costs of waterway projects and shift of major funding responsibilities to local sponsors brought attention to a design process that compensates for uncertainty with conservative rules of thumb (Bertsche and Cook, 1980; National Research Council [NRC], 1983).
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Shiphandling Simulation: Application to Waterway Design Port Development Development of port infrastructure over the past 2 centuries has evolved through a balance of technological demands required by shipping, urban conditions affecting the port, and public interest in port modernization. Shipping technology has required increasingly deeper and wider channels and waterways (McCallum, 1987; NRC, 1981, 1985). Modern shipping terminals require larger spaces to operate and connectivity to greater and more-efficient intermodal land transport capacity. Larger terminals with higher volumes of cargo are in conflict with the vehicular congestion associated with ports encroached by or developed in urban areas. Public support for port infrastructure modernization has softened. This decrease is due to competing demands for public investment funds for nonmaritime-related purposes in the port area (for example, residential and commercial developments, recreation sites, marine habitat preservation, restoration) and to heavier emphasis on environmental aspects of proposed waterway projects than in former years, especially the impacts of dredging and the disposal of dredged materials (Journal of Commerce , 1991a; Kagan, 1990; Marine Board, 1985; NRC, 1981, 1985, 1987; Rosselli et al., 1990; U.S. Maritime Administration, 1990). Keeping pace with rapid changes in technology while keeping costs manageable and accommodating environmental interests of public policy and public interests groups has become more difficult. The impact of the factors affecting modernization of the U.S. port infrastructure across the nation is selective. For example, some ports are experiencing extreme congestion on the land side due to differing urban conditions while other ports experience channel limitations on the marine side due to the timing of previous modernization. The overall result has been increasing demands on the local port and a lessening ability to solve port infrastructure problems. Nevertheless, various modernization projects are in progress. They vary from a $5 billion port development proposed for Los Angeles-Long Beach Harbor to a wider and deeper channel in Miami; from a new container terminal in Tacoma to better rail access in New York. In any one year, over $500 million in port-funded capital improvements for port facilities and waterways is typically under way (Journal of Commerce , 1991b) Water Resources Policy Although funding development of port facilities is the responsibility of civil authorities and private enterprise, the federal government has historically led development of the port and waterway system (Heine, 1980; National Research Council, 1983, 1985). The major costs of construction,
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Shiphandling Simulation: Application to Waterway Design WATERWAY TERMS AS USED IN THIS REPORT BASIN A comparatively large space in a dock, waterway, or canal system, which is configured to permit the turning or other maneuvering of vessels for entering or departing a dock or berth. BERTH A place where a vessel is moored at a wharf or lies at anchor. CANAL An excavated, dredged, or constructed watercourse, usually artificial, designed for navigation. Side borders usually extend above the water surface. CHANNEL Part of a watercourse used as a fairway for the passage of shipping. May be formed totally or in part through dredging. DOCK The water space between adjacent piers or wharves in which vessels are berthed; an artificial basin or enclosure fitted with lock gates to retain a level of water undisturbed by entering or departing vessels (wet dock); any dock in or on which a vessel can be made to lie completely out of the water (dry dock). FAIRWAY The main thoroughfare of shipping in a harbor or channel; although generally clear of obstructions, it may include a middle ground (that is, a shoal in a fairway having a channel on either side) suitably indicated by navigation marks (such as buoys). HARBOR A fully or partially enclosed body of water offering safe anchorage or reasonable shelter to vessels against adverse environmental conditions. May be natural, artificial, or a combination of both. PORT A place in which vessels load and discharge cargoes or passengers. Facilities in developed ports normally include berths, cargo handling and storage facilities, and land transportation connections. Normally a harbor city, town, or industrial complex. WATERWAY A water area providing a means of transportation from one place to another, principally a water area providing a regular route for water traffic, such as a bay, channel, passage or canal, and adjacent basins and berthing areas. May be natural, artificial, or a combination of both. WHARF A waterside structure, also referred to as a pier, at which a vessel may be berthed or at which cargo or passengers can be loaded or discharged. SOURCES: Bowditch, 1981; McEwen and Lewis, 1953; Rogers, 1984; U.S. Navy Hydrographic Office, 1956.
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Shiphandling Simulation: Application to Waterway Design VESSEL AND OPERATOR TERMS AS USED IN THIS REPORT BARGE A heavy, non-self-propelled vessel designed for carrying or lightering cargo. INTEGRATED TOW A flotilla of barges, tightly lashed to act as a unit. Common configuration found on shallow inland waterways. PILOT The person piloting (directing and controlling the maneuvering of) the vessel. In actual vessel operations, the pilot could be a licensed independent pilot, master or qualified deck officer. SHIP A self-propelled, decked vessel used in deep-water navigation. TOW One or more barges or other vessels being pulled, towed alongside, or pushed ahead. TUG, TUGBOAT, TOWBOAT A strongly built vessel specially designed to pull or push other vessels. VESSEL A general term referring to all types of watercraft including ships, barges, tugs, yachts, and small boats. SOURCES: McEwen and Lewis, 1953, Rogers, 1984. operation, and maintenance of federal navigation projects, channels, and waterways used by marine transportation has been funded and built by the U.S. Army Corps of Engineers (USACE). Until the 1970s, the federal government was the major source of funds for basic channel and waterway infrastructure, leaving actual port facility and land-side access up to local ports, other agencies, and private enterprise (especially for petroleum terminals). This redistribution of national resources directly benefitted local ports and their service areas, with indirect benefits accruing to the national interest in assuring the adequacy of the marine transportation system for regional and international commerce. In the 1980s, federal policy changed. The shifting of more financial responsibility to local sponsors (for example, port authorities) began with the imposition of user fees. Substantially increased requirements for local sponsorship resulted from passage of the Water Resources Development Act of 1986. The act envisioned partnerships between the federal government and nonfederal local project sponsors in which local sponsors would have a significant role in planning, design, and funding. The federal gov-
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Shiphandling Simulation: Application to Waterway Design ernment would continue to bear the major costs of basic waterways infrastructure, but local sponsors would be required to shoulder more of the cost for planning, construction, operations, and maintenance, and perhaps most importantly, responsibility for the disposal of dredged material. For example, local sponsors are required to share 50 percent of the costs of feasibility planning, provide the federal government with any needed real estate and property at 100 percent local sponsor expense, and contribute 50 percent of construction costs for the portion of project depths that exceed 45 feet. These dramatic changes in federal policy have elevated the attention given by local sponsors to project costs. The changes have prompted interest in scaling down design dimensions to the minimum necessary for safe operations and minimizing the amount of dredging and the volume of dredged materials that must be disposed of. Traditional design methods using rules of thumb increase design dimensions to compensate for uncertainty. They assure adequate margins of safety but provide little comfort to designers charged with achieving maximum cost-effectiveness (Bertsche and Cook, 1980; NRC, 1983). ROLE OF SIMULATION IN WATERWAY MODERNIZATION The design of a waterway is as much an art as a science. Design must address many different qualitative as well as quantitative factors affecting its cost and operability. These factors include the engineering, operational, scientific, environmental, economic, and political aspects of a waterway project. Determining the swept paths of the vessels that will ply a waterway, for example, is an essential step in its design. These paths will reveal the relative risks of passage that must be addressed in waterway design. Characteristics such as channel depth, width, and geometry are selected in an attempt to optimize the balance between risk and cost inherent in the design. A growing number of those involved in waterway design are applying high-technology systems to better determine the most cost-effective waterway configurations. One such technology, shiphandling simulation, has been used for operational training (for example, emergency procedures and maneuvering), analyzing marine casualties, evaluating vessel designs for maneuverability, evaluating bridge equipment, evaluating aids to navigation, and assessing the suitability of a particular vessel for a new port or transit situation. Shiphandling simulation techniques have also been used to select waterway configurations, usually as modifications to segments of an existing system, that accommodate economic, safety, and environmental interests. Additionally, available simulations have been used for multiple purposes of research, training, and waterway design (Ankudinov et al.,
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Shiphandling Simulation: Application to Waterway Design 1989; Burgers and Kok, 1988; Elzinga, 1982; Froese, 1988; Loman and van Maastrigt, 1988; McCallum, 1982; Paffett, 1981; Puglisi, 1987). Initial shiphandling simulations involved remotely controlled scale models or scale models of sufficient size to accommodate human operators. In recent years, computer-based simulation has benefitted greatly from the advance of computer technology to help determine the swept paths of ships and integrated tows (oceangoing and shallow draft) under a variety of waterway configurations and operating conditions. [This report typically refers to ships, ports, and waterways for convenience of discussion. Integrated tow operating environments (such as found in river systems) are also assessed using computer-based simulations (Miller, 1979)]. Computer simulations can be performed using human pilots in a simulated ship bridge (that is, a functional mock-up) and mathematical models of ship behavior to predict the response of the vessel to commands from the pilot. Simulation is also performed in fast time using computer-based pilot models instead of human pilots. Although computer simulations of both types have been used increasingly to aid in waterway design worldwide, there are many concerns about the practical application of the technology for this purpose. Widespread application has been hampered by questions of the validity and value of the results. This report assesses the validity of simulation as a design technique to better determine the feasibility, usefulness, and cost-effectiveness of computer simulations for the design process. It describes the waterway design process as it has traditionally been accomplished, the role of simulation in the design process, the components of a simulator, and the present state of practice. The application of simulators in several case studies is presented, and research needs are outlined.
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