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Dredging Coastal Ports: An Assessment of the Issues (1985)

Chapter: B: General Design Criteria for Dredged Navigational Facilities

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Suggested Citation:"B: General Design Criteria for Dredged Navigational Facilities." National Research Council. 1985. Dredging Coastal Ports: An Assessment of the Issues. Washington, DC: The National Academies Press. doi: 10.17226/608.
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Page 144
Suggested Citation:"B: General Design Criteria for Dredged Navigational Facilities." National Research Council. 1985. Dredging Coastal Ports: An Assessment of the Issues. Washington, DC: The National Academies Press. doi: 10.17226/608.
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Page 145
Suggested Citation:"B: General Design Criteria for Dredged Navigational Facilities." National Research Council. 1985. Dredging Coastal Ports: An Assessment of the Issues. Washington, DC: The National Academies Press. doi: 10.17226/608.
×
Page 146
Suggested Citation:"B: General Design Criteria for Dredged Navigational Facilities." National Research Council. 1985. Dredging Coastal Ports: An Assessment of the Issues. Washington, DC: The National Academies Press. doi: 10.17226/608.
×
Page 147
Suggested Citation:"B: General Design Criteria for Dredged Navigational Facilities." National Research Council. 1985. Dredging Coastal Ports: An Assessment of the Issues. Washington, DC: The National Academies Press. doi: 10.17226/608.
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Page 148

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APPENDIX B GENERAL DESIGN CRITERIA FOR . . DREDGED NAVIGATIONAL FACILITIES In 1972, the Permanent International Association of Navigation Congresses (PIANC) organized a commission to develop criteria for the reception of large vessels (IOTC, 1973~. Six years later, a PIANC working group again studied the requirements of large vessels (200,000 DWT and greater), and published recommendations for port design (ICORELS, 1980), as did a working group of the International Association of Ports and Harbors (COLS, 1981~. A review of PIANC guidelines is now under way, under the guidance of a new working group. The recommendations of these international organizations include guidelines for the dimensions of channels and maneuvering areas, and also address forces of the physical environment, equipment, and training. Maritime nations have developed general design criteria: those of Canada--TERMPOL--are based on prevention of oil pollution from marine casualties (Canadian Coast Guard, 1977~. The general guidelines developed for ports and harbors in Japan (Bureau of Ports and Harbours, 1980) are detailed, reflecting the economic significance of ports to the country, its challenging natural environment, and the need to balance economical design and construction and safety margins. The general design criteria used in the United States are developed by the U.S. Army Corps of Engineers. These were recently updated (U.S. Army Corps of Engineers, 1983~. Succeeding tables and figures describe and compare these general criteria. It should be understood that all these sets of criteria acknowledge the importance of "~1) the several site-specific factors of great importance to design, (2) the need for consultations with shipowners, pilots, and others, and (3) the need to employ analysis and design tools" (Crane, 1983~. 144

145 - -1 GRO! S UNDERKEEL CLEARANCE WATER AD MIS SABL£ DRA ~ . _ iVERTI"L ~T10N 4tS - LL AND ="r) _ _ _ _ _ _ _ _ _ ~ N~ ~D£RK££L CL"~NCE NO MINAL CHANNEl BED LEVEt ~ ~_ SOUNDING ACCURA~ SEDI - NTAtI~ ~E~ DR£~61NGS TOL£~ANCE FOR DREDGING (a) Conventional Net Underkeel Clearance Calculation, Definitions from PIANC (Permanent International Association of Navigation Congresses) t - PR£010TED TIDE - _ _ 1 CHARTED D£PTH 1 ~' T)~AL UNC£RTAINTY CHART DA T~ M STATIC DRA F1 UNCERTA IN~ UHCERTAIN~: ~SQUAT .~___, ~ SHIP WAT ER LfNE STATIC O"~ CHARTED OEPTH ·- ~- ;~ _ UNCERTAINTY ~ - --- ' iVE RESPONSE NQ~INAL S"BED ~_. ~ !_ _ _ _ ' !_ UNDERCUT SILSAt ION _.. (b) Statistical Underkeel Clearance Calculation FIGURE B-1 SOURCE: C. Lincoln Crane, Jr.

146 TABLE B-1 General Criteria for Depths of Dredged Navigational Facilities U.S. Army Corps of Engineers Ship's draft and sinkage + allowances for wind, waves, currents, type of bottom, etc. PIANC it_ Gross underkeel clearance 1.20 x ship's draft, exposed 1.15 x ship's draft, waiting area, exposed 1.07 x ship's draft, calmest area, least ship speed (berthing) Net underkeel clearance at least 0.5 m (1.7 ft) SHIPOWNERS Statistical TERMPOL (CANADA) 1.15 x ship's draft, exceptions require special underkeel clearance survey Japan Depth of maneuvering basin (1.10 x ship's draft) + allowances for wind, waves, currents, type of bottom, etc. LO UJ ,,, z LO ~z z `9 z z I: ~c, z ~> ~, (, , ~ y uJ y z z ~z z m ~V ~ Is ~ ~ ~0 ~ m ~ ~2 - _ ~ ~\ __ _ _ _ _ ~7 ~r ~, 1' ·1 CHANNEL WIDTH ONE WAY TRAFFIC CHANNNEL BAND CHANNEL /' BOU N DARI ES - _ ~\ MANEUVERING AREA y CHANNEL WIDTH TWO WAY TRAFFIC V CHA N N E L CEN TE RLl N E R . RADIUS OF CURVATURE I. R'0.8L ~ . W'0.10L V'0.35L X Y __ - I i I -2 :1 1 _ =a a' DIRECTION OF SHIP'S ENTRY SPEED '0.2m/s FIGURE B-2 Determining Channel Dimensions

147 TABLE B-2 Comparison of Port Design Guidelines for Channel Width (Referred to Dimensions of Design Vesselts)) One-Wav Traf f ic COE*1 TERMPOL PIANC Maneuvering Lane Straight channel Bends of 26° 4oo Bank Clearance Each side 2 . O bosom 4.2 beam 4.9 beam . 6 berm + 2.0 beam 4.0 beam 1.0 beam Additional Width ,> tW ~ L /BR+ length2/ (beam x radius) + Satety r.~argin .5 Passing Shin Clearance Between Lanes Total Width w/o Weather, Current Straight Channels Bends of 26o 4oo Weather and Current Clearance 3.2 beam 5.4 beam 6.1 beam + .9 beam Each side 4.0 beam 6.0 beam 1.0 beam Total both sides Total Width Straight Channels Bends, of 26° 4oo Paral le. 1 Bends Radius for Bends, of <25° 26°-3 5° >36° Width transition (total) Approximate Shin Size General Equation 5.0 beam 7.2 beam 7.9 beam + > 5 length 1:10 Smal1/medium size tanker 5.0 beam 7.0 beam w/o tugs 3 length 5 length 8 length 1:13 5 beam 5 beam2+ l length / (berm x radius ) 5-10 length Not Very ultra specified larger crude care ire I, _ Width ~ maneuvering lone + 2 bank clearance + weather & current clearance *Using values for "poor vessel controllability" U.S. Army Corps of Engineers (1983). 2Canadian Coast Guard (1977J. 3Permanent Int~rn~tiona1 Association of Navigation Congress;; (1980). COE*1 2.0 beam 4 . 2 beam 4. 9 beam .6 beam + .8 beam 6.0 beam + 10.4 beam 11.8 beam . 2+ . 9x2 ) beam Total both side TERMPOL 2.0 beam 4.0 bedim 1.0 beam . 1. 0 beam 7.0 beam 11.0 beam . 1. 0 beam Total per ship lane P IANC Definitions and Comments . . _ . Maneuvering lane (ML): - Lone in which a single vessel maneuvers - Accounts for uncertainty in vessel position and time lag to correct position - Applies to straight and turning, not ~>dditi~e - Required for each ship (i.e., MLX2 for 2-way traffic) - Can reduce it operations limits applied (e.g., 2 design ships don't pass each other and no passing in turns) Bank Clearance (BC): - Clearance to Ovoid bank suction - Ros~uir~d on both sides, BC x 2 for all channels . Passing Ship Clearance (PSC): - Between I=s to avoid interference _ r _ - Total straight Channel Width Without Current Clearance (W w/o WCC) - Artif icial since- cannot usually be used without WCC, even for mild conditions . Weather and Current Clearance (WCC): - For beam wind, -current, and waves which cause a yaw angle (10-15° max.) - Additiona; clearance should be made for varying conditions (gusts) And other factors - For design, must correspond to limiting env~ronmentd1 operating condition 8.0 Beam + (2) 12.4 beam + 13.8 beam 9.0 beam ~ ~ GS bear SAME AS ONE WAY 8 beam Sc:all/m`*dium Not very/ size tanker sp~cif fed ultra large crude- carrier - ~ 1 2 b k width ~ 2 maneuvering ane + an clearance + pi$~;~,ins ship clearance + weather And current clearance Total Width of Channel (w) at Design Depth: - In general, minimums are shown for design, however, local conditions; must be considered Radius of Turn (R): - Podium; of this- channel centerline for blinds; - TERMPOL gives max rudder angle (I) of 15° (related to the design ships' turning diameters at ~ ~ 15°) Transition: The ratio of widening ( sum of both Video.) to length along channel Ship Size: - The approximate ship Size for which the specific guide is intended (in terms of .tan~er$.~! ~ " ' G<~n~<r~1 Equation relating the, individual | components to the total width **Small-size Tanker:16,000 - 60,000 DWT t4edium-~>iz~ Tanker:60, 000 -120, 000 V`>ry~la~g~ ~ crude -arriver:120, 000 -320, 000 Ultra large crud carrier:More than 3:10, 000 DWT

148 TABLE B-3 General Criteria for Turning Basins and Anchorages TURNING BASINS U.S. Army Corps of Engineers Equal to area of circle with radius = 1.5 x ship's length over-all + allowances for congestion, sedimentation, current, etc. Side parallel to channel longer, ends angled 45° to channel boundary PIANC Equal to circular area with diameter = ship's length over-all Elliptical shape recommended Japan Equal to circular area with radius = 1.5 x ship's length over-all, ANCHORAGES U.S. Army Corps of Engineers Free-swinging Area = area of circle with radius = ship's length over-all + anchor chain (5x to 6x water depth) Fixed dolphins, berths Width = 1.5 x ship's beam parallel to channel PIANC None Japan Design Objective Offshore; · e waiting Mooring in storm Mooring Swinging Mooring with 2 anchors Seabed~Wind Good anchoring Bad anchoring Good anchoring Bad anchoring Wind vel. - 20 m/see (40 km) Wind vel. = 30 m/see (60 km) (LAO = ship's length over-all) Radius LOA + (6 x water depth) LOA + ~ 6 x water depth) + 30 m (99 ft) LOA + (4.5 x water depth) LOA + (4.5 x water depth) + 25 m (82.5) LOA + ~ 3 x water depth) + 90 m (297 ft) LOA + (4 x water depth) + 145 m (478.5 ft)

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Dredging Coastal Ports: An Assessment of the Issues Get This Book
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Are the nation's ports adequate for our present and future needs? This volume points out that no significant new deep-water construction has occurred for a decade, and provides the information and analysis needed to goad the ports and the federal government into action. The book asks three questions: Is additional port construction and maintenance dredging needed now or over the next 20 years? What would prevent dredging if it is needed? What alternatives could make additional dredging possible? The book identifies several problems in dredging ports, including the long interval between a decision to deepen a port and the time the alterations are complete. The United States needs to speed port construction to meet changing needs, and the committee recommends that we prepare for future needs by dredging now.

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