Harbour planning and design involves numerous technical, operational and environmental considerations. Select one (1) of the above aspect to perform literature study and produce a summarised write-up of up to 3 pages (excluding figures/ tables). Discuss how decision-making inevitably require the detailed study of the correlation between these diverse aspects as well as economic and financial constraints. Provide all references.
OPERATIONAL CONSIDERATIONS
Operational consideration gives guidance on general aspects such as the design life of structures, ship data, requirements of approach channel and other operational considerations. Many of the operational requirements of marine works and structures are specific to their particular functions.
Design Life
The design life of a structure or product is the period of time during which the item is expected by its designers to work within its specified parameters. The design life of a structure is taken to be its intended useful life, and will depend on the purpose for which it is used. The choice of design life is a matter to be decided in relation to each project. Unless special circumstances apply, the design life should be taken to be 50 years for all permanent marine structures covered. This does not necessarily mean that the structure will continue to be serviceable for that length of time without adequate inspection and maintenance. Rather, regular inspection and repair are required under competent direction to ensure the stability and serviceability of the structure.
Ship Data
Where possible, details and dimensions should be obtained from the client, owners and operators of the vessels to be accommodated, and those likely in the anticipated lifetime of the structure. Vessel characteristics which should be considered include type, size and shape, ship handling requirements, cargo or passenger handling requirements, and vessel servicing requirements. This is important so that the harbour could be design based on vessel size and shape.
Current Conditions
Current condition at that area is can be divide into the type of soil, the tidal flow and also the wave height. Reclamation, dredging works and major sea defense such as breakwaters may cause changes in the pattern of tidal flow and consequently affect navigation, mooring and berthing forces, siltation and water quality in the vicinity of these marine works, and possibly some distance away from the site. So this is very important to know what is the current condition at that place.
Berth Conditions
Berth is the designated location where a vessel may be moored, usually for the purposes of loading and unloading. Berths are designated by the management of a facility. Vessels are assigned to berths by these authorities. Acceptable wave conditions at berths for ferries and public vessels or within cargo handling basins and typhoon shelters can only be determined after consultation with the port management or other vessel operators.
Typhoon Shelters
A typhoon shelter is a shelter for fishing boat. These facilities are often found in Hong Kong Port. A typhoon shelter, is used by small to medium ships as a shelter against gale force winds and rough seas during a typhoon strike. Typhoon shelters in Hong Kong are to provide shelter for vessels not exceeding 50 m in length under extreme wave conditions in typhoons. The recommended wave heights under extreme wave conditions should not exceed the following criteria :
Vessel Length Significant Wave Height
Less than 30 m
Less than 0.6 m
30 m to 50 m Less than 0.9 m
It should be noted that the recommended design criteria should be taken only as the target design values instead of the absolute allowable values. Localized exceedance of the design values may be permitted with due consideration of the site condition and the layout of the mooring areas within the typhoon shelter.
Approach Channels
The depth and width of approach channels should be specified. The required depth of channels can be calculated based on several factor which is the loaded draft of design vessel, tidal variations, wave induces motion of the vessel, vessel squat and trim and a factor of safety. The width of the channel, defined as the width at the dredged level, should be determined according to the following factors :
Beam, speed and maneuverability of the design vessel.
Whether the vessel is to pass another vessel.
Channel depth.
Channel alignment.
Stability of the channel banks.
Winds, waves, currents and cross currents in the channel.
Availability of navigational aids.
Where the bottom of the channel consists of mud, it is usual in international ports to define the depth for navigation as being that between low water level and the level at which the density of the bottom sediment is equal to or greater than 1200 kg/m3, since research elsewhere has shown that the mud layers of lower density do not significantly impede the passage of a ship. The general practice to determine such a level in local port condition is to use an echo sounder of 200 kHz to 220 kHz which, by experience, is able to identify the seabed of density of 1200 kg/m3 in most cases for safe navigation. When planning the location of approach channels, and approaches or fairways in general, account should be taken of future siltation and maintenance. Consideration may be given to dredging to a depth greater than the minimum required navigation depth, with the intention of eliminating the need for maintenance dredging in the first few years after completion of initial dredging.
Navigation Aids
Aids to navigation are used to mark limits of structures such as piers, seawalls, breakwaters and dolphins, channel entrances, boundaries and turns, and hidden dangers such as shoals and rock outcrops, to act as a guide for vessels and to assist with their safe movement.
Discuss how decision-making inevitably require the detailed study of the correlation between these diverse aspects as well as economic and financial constraints.
In many engineering design, the economic and financial constraints is the most influential items. It can make the idea become reality or not. A civil engineer need more financial support to design a harbour with enough strength with good material so that the harbour will have longer design life. Apart from that, the reclamation process to find the suitable soil type area to built a harbour is important. This will need more financial and time being. Another part is on the channel way. Suitable channel way is important so that the vessel do not experience any difficulty in the future. Inevitably, engineer should know and make a decision making to choose suitable area for harbour development.
REFERENCE
Nobuyuki Yagi, Evaluating Integrated Coastal Management planning policy in Japan: Why the Guideline 2000 has not been implemented.
Original Research Article Ocean & Coastal Management, Volume 84, November 203, Pages 97-106 .
http://en.wikipedia.org/wiki/Ecology retrieved on 1 December 2013.
http://en.wikipedia.org/wiki/Berth_(moorings) retrieve on 1 December 2013.
Civil Engineering Department, Government of Hong Kong, Port Works Design Manual Part 1, May 2002.
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