Excerpts from lecture material on lock canals
Alternative System for the Expansion of the Panama Canal
thatSets a Higher Limit to Obtainable Capacity
Reduces Risks Maximizes Profitability Potential
Bert G. Shelton, B.Sc., M.Sc., P.E.Research Scientist & Engineer
Bert G. Shelton: Credentials
•Research Scientist & Inventor: Ship-Lift & Lock Design Patents•Professional Engineer: 30+ years International Experience•Masters in Civil Engineering – Structures, University of Texas (UT), Austin•Consultant to Offshore Oil and Service Companies •Specializing in the Development of Innovative Design Solutions •Major Offshore Projects Internationally - All Oceans and Climates
–Heavy Piled and Massive Gravity foundation design–Fixed, Compliant and Floating drilling & production platforms: structural & installation design–Design & Installation of sub-sea pipelines and structural components–Design & Analysis of heavy lifts and load-outs–Dock & Skid-Rail design for heavy load-outs
•Research Experience established at UT and at Exxon Production Research Co.•Born in US / Raised in Panama; reside in both; multilingual, multicultural•Qualifications: Lifelong Experience w/ Panama Canal System & Territory•Contact Telephones: USA +1-713-723-1404; Panama +507-223-6163
Current Expansion Plan: Description
Adds ONE larger new shipping lane to the canal.Uses water-saving SIDE-TANK locks.
Includes:• Building 2 three-step single-lane lock units; one at each end• Digging & dredging new channels• Enlarging existing channels
Appears to fully use available water resources.
Alternative Expansion Plan:Description
Adds TWO larger new shipping lanes to the canal.Uses water-saving SLAVE-TANK locks.
Includes:• Building 2 single-step twin-lane lock units at each end• Less digging & dredging of new channels• Less deepening of existing lake-level channels
Allows yet another expansion with existing water
Alternative Expansion Plan:Proposed System Layout
Following are schematics that depict Plan and Elevation Views
of the Slave-Tank Lock System Layouts
at each end of the Panama Canal.
First is presented the schematic for the canal’s Pacific entrance; followed by the schematic for the Atlantic entrance.
The two twin-lane lock units of the Pacific System would be at opposite ends of Miraflores Lake, as is the case with the present locks.
• The lower Pacific Locks would lift ~56ft
• The upper Pacific Locks would lift ~30ft.
Next is presented the schematic for the canal’s Atlantic entrance
Comment on the Pacific Lock System
Comment on the Atlantic Lock System
A Section of Channel separates the lock steps at mid-level.
• The lift height from ocean-to-lake is split equally;
the height of each lift is ~43ft.
• A transiting ship would first be lifted or lowered
from the ocean or lake to the mid-level channel.
• Next, the ship would be lifted or lowered from the
mid-level channel to the lake or ocean.
Operation of a Slave-Tank Lock
Four-step lock operation cuts transit water-use to one-third (1/3).
Two-thirds (2/3) are recycled in the process.
Description of Details on the Slides
Each cross-section shown depicts paired lock chambers, and a pair of recycling tanks. Pipes, culverts and valves interconnect them.
• Water is shown in blue.• Smaller circles are valves. • Valves circles are red when closed and blue when open.• The larger blue circles represent large culverts that run parallel to, and the full length of, the chambers.• Water flow is by gravity• Arrows indicate the water flow direction when valves are open• Inlet and Outlet Valves at each end of the culverts are shown,
respectively above and below the culverts at an angle.
NOTE: All pipes and culverts are full of water during operation. Valves are opened, then closed, in set sequences during operation.
Plan Comparisons:Key Details
2 (Reduced Risk)
8 (1/3 more chambers)
6 (2/3’s of the tanks) (base-case design)
16 18-22** (2/3 more transits) (w/ less total water-use)
1 (Shut-Down Risk)
Sliding Main-GatesLarge Transits-per-day
* Reduced transits through the old locks probable due to tenuous water availability,
which would lower overall canal transit totals for the current plan.
** The alternative plan’s options insure present and future operating water availability.
Plan Comparisons:System Water-Use
Existing Style Lock System: Traditional Mode 59 – 60.5 Water-Saving Mode 30 – 31
SIDE-TANK Style Lock System: 24 – 25depending on lane reversal frequency (next day vs. same day)
SLAVE-TANK Style Lock System: 12 – 16***depending on the waterway and lock unit details chosen
* Lifting and lowering water volumes expended to completing a transit are summed. ** Multiply chamber-ft of depth by the chamber’s width and length to obtain volume.*** Base-case design. Pedro Miguel needs no tanks as Miraflores water-use controls.
Volume** of water inChamber-ft of depthOperating Volume per Transit*
Water-Use Details:Existing Style Lock System
(1-step, 2-step and 3-step lock units)
3-step locks, as are today’s Gatun Locks at the Canal’s Atlantic entrance, cut lift/lowering water-use to a third. Ocean-to-Gatun Lake average water-use is reduced from 86 chamber-ft to 28.67ft.
2-step locks, as in Miraflores at the Canal’s Pacific entrance, cut ocean-to-Miraflores Lake lift/lowering water-use in half from ~56 chamber-ft to ~28ft. The 1-step Pacific entrance locks at Pedro Miguel lift/lower between Miraflores & Gatun Lakes and use slightly more water at ~30 chamber-ft to complete the Pacific lift.
This style system’s per-transit water-use is 59-60.5* chamber-ftof depth, allowing for changing lake levels.
* System’s optional water-saving mode cuts the totals in half to 30-31 chamber-ft per transit.
Water-Use Details:Side-Tank Style Lock System
The 3-step side-tank system, planned for Panama, will cut lift & lowering water-use at each end to a third. Thus, ocean-to-Gatun Lake 86 chamber-ft of lift/lowering water-use reduces to 28.67ft.
The system’s triple-side-tank locks further reduce use to 11.5ft , which when adjusted for lane reversals, increases to 12.0-12.5ft.
The added 0.5ft - 1.0ft. represents a system water-expenditure, which must be proportionally charged back to ships transited. The extra water-use depends on whether the lane is reversed daily or if ships travel one way one day and the other way the next.
Total per-transit use for this system is between 24-25 chamber-ft of depth. (Estimating lake fluctuation effects on this is difficult.)
Water-Use Details:Slave-Tank Style Lock System (Atlantic)
The 2-step slave-tank system proposed for the Atlantic entrance permits cutting lift/lowering water-use in half. Atlantic Ocean-to-Gatun Lake water-use is thus reduced from 86 chamber-ft to 43ft.
Separating the steps with a channel section allows ships transiting in opposite directions to get by each other so a ship headed the other way can enter the vacated chamber. This transit-by-transit lane reversal cuts water-use in half from 43 chamber-ft to 21.5ft.
Slave-tank lock operations reduce that 21.5 ft to between 7.2ft and 5.4ft per lift or lowering operation at the Atlantic end. That use range depends on design options and operating approaches chosen.
Water-Use Details:Slave-Tank Style Lock System (Pacific)
The 2-steps of the slave-tank system proposed for the Pacific canal entrance would be separated by Miraflores Lake. The 56ft lift to that lake from the ocean controls water-use at the Canal’s Pacific entrance. (The Miraflores to Gatun Lake lift is less at 30 ft.*)
Transit-by-transit lane reversals will cut the 56 chamber-ft of lift water in half to 28 chamber-ft.
Optimally operating the slave-tank locks, which includes using a tide-management procedure, reduces that 28ft to between 8.8ft and 6.6ft per Pacific end lift or lowering operation. That use-range variation depends on design options & operating approach chosen.
* Transit-by-transit lane reversals cut the 30ft lift from Miraflores to Gatun Lake in half to 15ft. Sharing water between chambers – w/o slave-tanks – can reduce those 15ft to 7.5ft.
Total per-transit for this system is between 12-16 chamber-ft of depth.
Final water-use depends on choices made among:• Slave-Tank Lock water-saving options • System configuration alternatives• Operating approach options
Water-Use Details:Slave-Tank Style Lock System Total
Plan Comparisons:System Transit-Times
Transit Operating Procedures
12 large transits/day SIDE-TANK* Lock System: ships transited in groups, one direction at a time
lifted in series, lowered in series * increasing the number of side-tanks to reduce water-use and increase efficiency does not work for lack of time.
18-22 large transits/day SLAVE-TANK** Lock System: ship transit-direction alternated
transit-by-transit to maximize yield. ** Alternative is available for further reducing water-use to
maintain transits during dry season or for adding lanes.
Plan Comparisons:System Transit-Times
The side-tank system’s 12 daily transits are assumed to include one lane-reversal-cycle.
- the (+/-)6 ships that enter each end of this single-lane lock system are assumed to exit the other end the same day.
- each ship will have ~1.5 hours to enter, be raise or lowered, then clear the first chamber before the next ship can enter.
Note: This estimate does account for the time needed by the last ship of a series to clear the three lock-steps before the first
ship sailing the other way can enter its first lock chamber.
Transit of a Three-Step SIDE-TANK Lock Unit
For reversing a single-step lock transit-by-transit, it is estimated that a transit cycle can take up to 2.5 hours.
It is estimated to take ~1.5 hours for the first ship to enter a lock chamber, be raised or lowered, then exit and clear the locks.
- Only after a ship exits the chamber and sails clear of the path can a ship going the other way align to enter the chamber.
Ship aligning can add from 0.5 hours to 1.0 hours to the cycle.
RESULT: 9-11 transits/lane per day; 18-22 total daily transits
Transit of a Single-Step SLAVE-TANK Lock Unit
Plan Comparisons:System Transit-Times
Alternative Expansion Plan:Slave-Tank System Qualities
Increases Canal Capacity by Operating More Effectively:
- Significantly increases service obtained per component built
- Triples cargo transits with a comparable construction effort
- Increases yield by simply arranging standard components differently, allowing more effective operation of the system
- Uses standard ship-handling and water fill/drain procedures when operated
Optimally Combines Old and New Lock Operations:• Draft limits for ships transiting the old locks are not changed
• Does not require changing Gatun Lake fluctuation range
• Comparatively reduces salt intrusion significantly
Efficiently Uses Available Canal Water:• Allows two-lanes w/ even LARGER chambers to be built NOW*
• Allows adding TWO MORE LARGER-LANES LATER*
* presently available water used; finding more water can be reserved for climate changes.
Alternative Expansion Plan:Qualities (Cont.)
Alternative Expansion Plan:Risk Reduction
Improves Service Reliability:
Operational risks reduced: • avoids building of dam across known geologic fault • two lanes reduce large-ship transit interruption risk• improves tugboat task of guiding ships into restrictive chambers• avoids increased old-lock transit drafts during the dry-season• offers measures to counteract increasingly limited water supply
Risk of triggering revolts reduced:• Potential to salt-up nation’s primary freshwater reserve lessened• Delays need to expand canal watershed into productive farms & protective rainforests to make-up for dry-season water shortages
Alternative Expansion Plan:Recommendations
Build a Slave-Tank system instead of a Side-Tank system, and routinely operate it in its most efficient “Balanced Mode”:
- Water-use is cut in half with transit-by-transit lock reversals.- Permits ~10 new-lock transits per lane per day.- Faster, less efficient, emergency transits (as for a battleship) are possible.
Build larger new-lock chambers:- Permits profitable smaller ship tandem transits, when no large ship is
waiting to transit, plus permits even larger ships than presently planned.- Improves handling of the “typical” large ship in and out of the chambers.
Manage overall Canal traffic imbalances with the old locks:- Maximum large ship transits are ~10 per day in one direction.- When large ship transits are out of balance, tandem smaller ships replace
the missing larger ship; old locks can absorb transit imbalances created.
Alternative Expansion Plan: Recommendations (cont.)
Optimally use old locks to maximize combined system yield:- New-lock operating water is obtained from the old locks - Old-locks are operated in 50% or 100% water-use mode, as needed
(these water-use rates can be obtained irrespective of ship transit direction)
Revise old-lock operating procedures and reduce daily transits of those by up to 1/3rd to obtain new-lock operating water which:
- Saves up to 2/3rds of the water now used by the old locks.- Permits operating up to 4 new post-panamax lanes with the water saved.
- 2 new lanes, transiting ~20 post-panamax ships a day use 1/3 of today’s water.- Building 1 pair of new lanes would nearly triple Canal cargo capacity.- Building 2 pair of new lanes would more than quadruple Canal cargo capacity.
All techniques and technology required are known & accepted.
Alternative Expansion Plan:Benefits of the Slave-Tank Lock Plan: Recap
A twin-lane system avoids the risk of a closure that can stop large ship transits.
Adding a channel section between Atlantic lock-steps improves the system.- increases water-use efficiency- permits 20 large transits per day vs. current plan’s 12 with less water- permits effective control of saltwater intrusion
Avoids inefficient, costly, risky and more damaging bypass of Miraflores Lake.- holding Gatun Lake at Pedro Miguel is preferable to crossing an area of
known faults with a new dam that adds a risk of losing Gatun Lake- including Miraflores Lake greatly reduces channel digging & dredging - diggings already done by the US are better incorporated- 20 vs. 12 new large transits can be obtained by including Miraflores lake- saltwater intrusion can be effectively controlled by including this lake
Alternative Expansion Plan:Benefits Recap. (cont.)
Avoiding Gatun Lake level operating-range change would- reduce complexity of lock operations - reduce upper channel deepening by 4ft, thus avoid a lot of rock blasting- remove risk of old-lock ship-drafts being reduced in dry season- maintain today’s trusted lake-level control systems and safety margins- remove the need to modify all lakeside facilities, public and private- avoid the need to enhance locks, spillways, main dams and saddle dams- insure viability of secondary lake uses
Revising old-lock operations reduces water-shortage operational uncertainty.
Enlarging watershed can be reserved for future climate change management.
Future presentation subject: proposed slave-tank system also considers tide management techniques that reduce water-use.
Alternative Expansion Plan:Closing Statement
By arranging most effectively what is built, the yield obtained from the available water-resources is significantly increased, yet project costs will not increase in proportion to the increase in yield.
Requiring 1/3 more chambers, the costliest element of a lock system, suggests the proposed plan will cost 1/3 more than the current plan. However, from that price one must deduct for relatively fewer tanks & associated piping, as well as relatively less digging.
Benefits from a 2/3 transit increase and the lesser risk level of the alternative are sure to exceed any added cost for making the change.
If that’s not sufficient reason to opt for the alternative, the potential it leaves for growth in the future most definitely puts it over the top.
Slide Show (for Reference)
Operation of the Side-Tank locks
Four-step lock operation cuts transit water-use to two-fifths (2/5).
Three-fifths (3/5) are recycled in the process.