Shiphandling Simulation Application to Waterway Design (1992) / Chapter Skim
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2. Waterway Design Process
2. Waterway Design Process
Pages 9-22
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From page 9... ...
However, the engineering concepts used in waterway design are essentially the same. A waterway design defines the form and dimensional boundaries required to meet functional objectives consistent with fundamental civil engineering practices and construction options.
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From page 10... ...
Principal design elements of form that are required to be determined and dimensions that must be developed for a given waterway are the following (Adcins and Bertsche, 1980; Dand, 1981; Marine Board, 1985; McAleer et al., 1965; McCartney, 1985; Norrbin, 1986; USACE, 1983~: location orientation or alignment depth width radius of curvature of bends tangent distance between bends aids to navigation These elements and their dimensions are primarily a function of the d~mensions of the design vessel, its track, and its expected vertical and horizontal movement as it transits the waterway. Additional clearance dimensions to allow for uncertainty of position, operational safety, and hydrodynamic requirements are also required.
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From page 11... ...
Selection of the design vessel is a defining decision in the design process, regardless of design aids used (US ACE, 1983~. · Dynamic behavioral characteristics must be determined for the design vessel (or vessels)
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From page 12... ...
Moreover, the use of simulation has the potential to reduce the extra margins traditionally used to overcome uncertainty, thereby reducing construction and maintenance costs. Although this benefit may appeal to the project sponsor, it is the significant design refinement opportunities afforded by simulation that lead directly to the question of whether the fidelity of the technique justifies reliance on it over
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From page 13... ...
As a result, waterway development processes have come under much greater scrutiny by local interest groups, resulting in a lengthening of the already long approval process (Kagan, 1990; NRC, 1987~. In the United States, for example, the time interval between design study and construction for a federal waterway project is frequently more than 20 years (NRC, 1985)
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From page 14... ...
Assessing the effectiveness of waterway design once a project is constructed, the adequacy of the design for use by vessels exceeding design vessel characteristics, and the accuracy of simulation predictions are not elements of current practice. Furthennore, no one, including the Army Corps of Eng~neers, Coast Guard, or project sponsors, appears to be overseeing operations to assure that vessels using a waterway remain within the vessel operating characteristics for which the waterway was designed.
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From page 15... ...
May include state and port authorities, terminal operators, shipping companies, and pilot associations. PUBLIC INTEREST GROUPS Organized representatives Tom Be public sector who have a direct or indirect interest in waterway projects.
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From page 16... ...
SWEPT PATH ENVELOPE The outer boundaries of the swept padres with He most extreme deviations from target Lack that encompass all of die swept paths of the vessels that transited the waterway. TRACK A trace of the path of a vessel as it makes its transit of a waterway.
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From page 17... ...
The elements are depth, width, aids to navigation, environmental data and civil engineering, and design vessel.
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From page 18... ...
Calculation of depth requirements involves the determination of critical sea and meteorological conditions, vessel operations, and other factors Hat affect the vertical motions and chance dimension errors. Because it is unlikely Hat maximum conditions for all factors will occur simultaneously, some designers have attempted to determine depth requirements by probabilistic forecasts.
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From page 19... ...
A trace of the design vessel's extremities outlines and defines its swept path. The maneuvering lane is intended to provide an envelope of all the expected swept paths of the vessels that will transit the waterway under the various assumed design conditions.
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From page 20... ...
The waterway designer must carefully allow accuracy tolerances for behavioral modifications relevant to maneuvering strategies that may result from the type and placement of aids to navigation. Because unbroken delineation of channel boundaries and traffic lanes is typically not feasible in a waterway or fairway, the relationship of the vessel to its intended track is determined either by electronic or visual fixes (with some lag behind actual positions due to human and electronic processing time)
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From page 21... ...
In actual practice, vessels used in most waterways differ substantially from what the designer had forecast 20 or more years earlier. In the committee's view, major reasons for this discrepancy inclllde: · dramatic changes in the form and composition of the national and worldwide merchant fleets made available through modern technologies; · the time scale of the waterway development process, which is longer than the working life of a typical ship; and · the absence of a waterways management regimen that restricts vessel access only to vessels that do not exceed design vessel characteristics (which could have the potential side effect of impeding development of maritime technologies)
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From page 22... ...
SUMMARY Waterway design, whether for new construction, improvement of an existing waterway, or appraisal of the capacity of a waterway, involves estimating the navigation requirements of an assumed vessel or vessels, coupled with estimates of the civil engineering factors. Present technology allows calculation and mathematical modeling of the factors that affect waterway width and form in the horizontal plane, but considerable judgment still needs to be applied.
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