MARSHALING YARD OPERATIONS
|This chapter implements STANAG 2926.|
The loading and discharging of vessels are dedicated to rapid, efficient, and controlled movement of cargo between ship and shore. Improvements in cargo packaging, particularly containerization, add greatly to ship and cargo-handling productivity. The cargo marshaling yard is an essential part of this shoreside operation. It provides a place to hold and process cargo pending further movement. This chapter specifically addresses the container marshaling yard. However, much of the discussion applies as well to break-bulk cargo operations.
Use of a marshaling area allows rapid clearing of the beach or pier. It makes vessel working space available for its primary purpose. It reduces pier congestion, thus reducing the potential for work slowdowns or stoppages in discharge operations. Ideally, containers and other cargo should go from ship's hook directly onto line-haul equipment for movement inland. In most cases this is not possible except for selected containers or other cargoes. Conceptually, all cargo should move through the terminal without delay. However, this is not always possible because of the following:
- The consignee's reception capacity maybe limited.
- The movement plan causes delays in clearance.
- Damaged containers may require repair or restowing of contents before further movement.
- The consignee may move, causing some delay.
- Containers may require segregation by destination or priority.
- Containers occasionally require redocumentation before further movement.
- Some retrograde containers must be cleaned and fumigated.
- Containers found with broken seals or apparent pilferage must be inventoried and a new seal applied before onward movement.
The container (cargo) marshaling yard is a temporary, in-transit storage area. It expedites discharge operations by facilitating rapid and continuous movement of cargo and/or containers to or from the beach or pier. Marshaling cargo allows leveling of line-haul peak workloads that result from discharge operations. Concurrently, marshaling cargo allows selective, controlled, and flexible phasing of container or cargo movement to destination or vessel. In container operations, the terminal provides an area for the containers for the following:
- Maintenance, repair, servicing, and inspection.
- Cleaning and decontamination.
- Marshaling for retrograde movement.
STANAG 2926 (see Appendix C) ensures that national containerization procedures are internationally compatible and interoperable. This STANAG also includes factors relating to container selection, handling, inspection, and stuffing.
A marshaling yard has no set organization or physical layout. It is organized to meet operational requirements within available space. By grouping related functions, the design of the marshaling yard will eliminate lost motion, reduce container and cargohandling requirements, and permit a logical flow of containers and cargo through the terminal.
Cargo can be subdivided into any number of categories. The most widely used categories are general (break-bulk), containerized, RO/RO (vehicles and containers on chassis), and special (oversize, heavy lift, hazardous, and security) cargo. These categories and the volume of cargo in each category plays a significant role in marshaling yard organization.
All terminals should provide for the following activities and functions:
- A central control and inspection point with multiple lanes for cargo and containers entering or leaving the marshaling yard.
- Auxiliary internal checkpoints for containers and cargo entering the yard from a beach, from a rail spur, or by helicopter to a landing pad within the yard.
- A traffic circulation plan depicting movement flow into, through, and out of the marshaling area.
- Segregation of inbound containers and cargo by size and type. Within these groupings, further segregation by priority, destination, and special handling (security, mail, and hazardous) requirements.
- Segregation of retrograde cargo and containers by type and size with empty and loaded containers further segregated.
- Running inventory of containers by location and status within the yard.
- Security area for break-bulk or containerized sensitive and high-dollar-value cargo.
- External power source for refrigerated containers. (In an unimproved or bare beach LOTS environment, self-contained refrigeration units may be needed. This mandates separate propane or diesel refueling areas.) Refrigeration maintenance must also be provided.
- Sheltered facilities for inventory and control, documentation, and movement control elements.
- Covered facilities for stowing and unstowing containers and repairing cargo.
- Cleaning and/or decontamination of retrograde containers and vehicles.
- Minor repair of damaged containers.
- Equipment parking.
- Unit maintenance of equipment.
- Messing and comfort facilities.
- Spill contingency plans including emergency sup-plies and equipment for containing and disposing of hazardous material spills.
- Disposal of hazardous and special waste IAW federal, state, local, and HN environmental regulations.
A suggested general scheme for a container marshaling yard in an unimproved or bare beach LOTS environment is shown in Figure 6-1. The organization of and traffic flow through a fixed-port container transfer facility is shown in Figure 6-2.
The marshaling area in a TO provides essentially the same facilities. In addition to the space for temporary storage of containers, it needs space for any container repacking requirements, container repair, or other operational or administrative functions. Space requirements are influenced by the type, size, and number of containers handled; the length of time containers are held in the marshaling area; and available CHE.
Surfacing of existing ports and those under construction is intended to support commercially operated equipment. The load-bearing capacities will meet foreseeable requirements.
Fixed and Semifixed Ports
Semifixed port surfacing has essentially the same load-bearing capacities as those of the fixed port. The type and quantities of cargo are essentially identical.
LOTS Operations (Unimproved Facility or Bare Beach)
In a LOTS environment, the marshaling yard surface may be subjected to loads of about 218,000 pounds (50,000-pound frontloader with a 40-foot container). Normally, beach movement of containers would be restricted to 20-foot containers or less. However, containers up to 40 feet may be used. An unimproved or bare beach facility does not normally have any surfaced area. Such surfacing must be provided comparable to that in a fixed or semifixed facility. A minimum surface would consist of 9 inches of rock or shell subgrade covered with an equal thickness of blacktop. Time constraints would prevent this type of construction in a LOTS environment. The materials below may prove useful to support limited loads in LOTS operations.
Matting, AM-2. This is a Navy-developed, extruded aluminum airfield mat. It is designed to support jet aircraft over soft, fine-grained soil. Because of limited stocks, high cost, and high priority for airfield use, this material will probably not be available for marshaling area use.
Matting, XM-19. This Army-developed, aluminum honeycomb-core, sandwich-type airfield landing mat is intended to support cargo and selected aircraft over soft soils. Limited stocks and priority for airfield use also restrict availability of this product.
Matting, M8A1. This is a corrugated steel airfield mat. It supports container-loaded trailers over sand, other granulated soils, and most relatively dry, finegrained soils (clay and silt).
MO-MAT. This fiberglass-reinforced plastic is laid in sections that maybe bolted together or overlapped. It is less susceptible to water penetration and more easily placed than metal matting. It is effective over beach sand, granular soils, and some fine-grained soils (clay and silt). It relies on the support provided by underlying soils.
ON-FAST. This is fiberglass cloth, hand sprayed with polyester resin for reinforcement. Unless broken, it does not allow water penetration. It achieves support from underlying soils and is effective over beach sand, granular soils, and some fine-grained soils (clay and silt). Increasing the thickness and fiberglass reinforcement increases the matting strength.
The marshaling area (general cargo or container, or both) is located as near the vessel, rail, air, or truck discharge or load site as practicable. Enemy capabilities and activities may require dispersion of activities or may otherwise effect the selection of the marshaling yard location.
Fixed and Semifixed Ports
The marshaling yard in an existing port is normally next to the pier area with a sufficient pier apron (100 to 500 feet) between the yard and shipside. These distances accommodate container discharge and container clearance activities and are more than adequate for general cargo operations. Rail spurs, warehouses, and similar facilities usually exist but may require rehabilitation. The semifixed port is constructed to replace an unimproved or bare beach LOTS site when a suitable fixed port is not available. Layout and construction of the semifixed port parallels that of the fixed port. Construction of the marshaling yard should encompass any existing hardstand, structures, and rail lines.
LOTS Terminal (Unimproved Facility/Bare Beach Operations)
The LOTS marshaling yard should be approximately 1/4 to 1/2 mile (.4 to .8 kilometer) inland from the beach or dune area to allow an acceptable rate of beach clearance. The maximum distance should not exceed that needed for operations. LOTS operations are inherently inefficient. They should be used only until fixed facilities can be placed in operation or until semifixed facilities can be constructed. Port operational considerations and construction details dictate the length of time LOTS operations continue. Factors that influence marshaling yard site selection in a LOTS environment (unimproved facility/bare beach) consist of the following:
Accessibility. Is the area readily accessible from the MSR and from the beach? Are internal road nets adequate? If helicopter operations are anticipated, are there any flight obstructions? Is the proposed site next to existing rail facilities?
Physical facilities. Are usable physical facilities available? Are they served by more than one entrance and exit? Are usable hardstands, airfields, railways or rail spurs, buildings, storage sheds, or warehouses in the area?
Adequacy of space. Will available space hold the type, size, and quantity of cargo and containers programmed for the area? Is there adequate area for working and intersecting aisles? Will available space accommodate administrative activities; repair, maintenance, and decontamination operations; retrograde staging; and storage of handling equipment? Is there sufficient area to stage line-haul equipment pending entry into the marshaling yard for loading?
Gradient, drainage, and soil characteristics. Is the marshaling area sufficiently level, with minor grading, to permit general cargo stacking and two-high container stacking without toppling? Are surface and subsoil drainage adequate? What is the depth and type of subsoil? Is the surface soil compatible? Does the soil need compaction, stabilization, or surface matting?
Engineer support. Is engineer support required? Is support available? What type of support? Is the support cost justified? If engineer support is not available, can transportation units make the site usable?
Containers may be placed in the marshaling yard either on chassis or stacked off chassis. Keeping containers on chassis reduces container handling and accelerates operations. However, when containers stay on chassis throughout the system, one chassis for every two to three containers is needed to support the system. Storing containers on chassis also increases space requirements in the marshaling area.
The Army operational concept is to stack load containers off chassis, with a maximum of two high, using the turret stacking method. Retrograde empty containers can be stacked five high if this height is within the capability of CHE. Other space considerations include stacking collapsed flat racks. Flat racks should be stacked as high as possible by available CHE in an area that facilitates retrograde for eventual back-loading. Although stacking containers increases handling, it requires fewer chassis and reduces requirements for marshaling yard space. The primary configurations of off chassis stacking are ribbon stacking, block stacking, and turret stacking.
Use this configuration (see Figure 6-3) when selective extraction of containers from the stack is not needed. This method requires more space than block stacking but is more space efficient than turret stacking. Use the ribbon stacking method if selective extraction is not required.
Use this system (see Figure 6-4) when the containers have a common destination or when selective extraction of containers from the stack is not needed. This method is particularly suited to stacking (either empty or loaded) identical retrograde containers. It is the most effective use of marshaling yard space.
This procedure (see Figures 6-5 and 6-6,) requires less container-handling for selective container extraction than does ribbon or block stacking. Of the three off chassis configurations, turret stacking least effectively uses space. However, it greatly enhances the marshaling yard's throughput or retrograde operations where selective container-handling is necessary. Although three-high turret stacking is shown in Figure 6-6 the Army concept is to stack loaded containers only two high.
The container-on-chassis marshaling system (see Figure 6-7) is most often used in commercial operations. Container-on-chassis marshaling is normally used in marine terminal operations where the container is lifted off the containership directly onto land transport or in RO/RO operations where the container-on-chassis rig is towed ashore from the RO/RO ship. Marshaling containers on chassis reduces container-handling and increases mobility and flexibility of operations. This method increases marshaling yard space requirements. It dictates a 2 to 1 or 3 to 1, or better, container-to-chassis ratio.
Numerous factors and combinations of factors dictate container stacking space requirements. Primary factors include the following:
Ribbon stacking requires more space than block stacking: turret stacking, more than ribbon stacking. Concurrently, one high stacking requires about twice the space of two-high stacking for the same number of containers. The relative space requirements of on chassis versus off chassis stacking are obvious.
Skill of Equipment Operators
Less skilled operators require more time to operate equipment. As operating skills increase, the need for more time decreases.
Physical Characteristics of CHE and Container Size
The recommended minimum operating space is a 15-foot working aisle with a 50-foot intersecting (turning) aisle when using sideloaders (see Figure 6-3). When using a frontloader, the overall length of the container being carried determines the effective width of the frontloader. For example, with a 20-foot container, the width of the vehicle is 20 feet. In a 90-degree stacking operation, a typical frontloader carrying a 20-foot container has a 45-foot turning radius. Aisle width must be adjusted to accommodate different container lengths.
Figures 6-8 through 6-14 present conceptual procedures for computing space requirements to stack containers in a marshaling yard. The concept envisions making clusters of containers grouped as needed to accommodate specific operational requirements or environments. Clusters are developed for turret stacking, block stacking, and on chassis parking for 20-, 35-, and 40-foot containers. Variations accommodate turret frontloader or sideloader stacking. The intersecting aisles are omitted in Figures 6-8 through 6-13.
Using the container cluster concept provides a relatively uncomplicated means of developing a marshaling yard commensurate with the needs of a specific operation or environment. This is done by grouping clusters within available real estate, modifying cluster dimensions where necessary, and adding areas to provide the related activities. Figure 6-15 shows a traffic pattern in on chassis marshaling area. Figure 6-16 shows a hypothetical marshaling area developed within the cluster grouping concept. It is designed to support simultaneous discharge and/or back-load of one containership in a fixed marine terminal operation. Intersecting aisles of the required width are placed around each separate container cluster. When two clusters are adjacent, they use a common intersecting aisle of the required width (see Figure 6-16). Figure 6-17 shows a pattern using one-way traffic where possible.
The objective in any shop discharge operation is to minimize the turnaround time of the ship. One way to do this is to always have the terminal tractors available and positioned properly at the cranes working the ship. To do this efficiently, with minimum congestion, the tractors should travel the least distance possible. The stacking areas should correspond directly behind the crane's current working position at shipside. Hence, the two-deep stacking area can accomodate boxes from either crane as they work their way amidship. Each stacking area should be divided for import and export containers. Areas are divided to ease the dropoff of import containers and the pickup of export containers in one counterclockwise trip around the stacking area. One transportation company, terminal service, TOE 55-827L, works each containership. Operating on a 24-hour basis, the unit should handle (load and/or unload) 600 containers per 24-hour period.
Container Off-load and/or Back-load Operations
To off-load and/or back-load a containership, a minimum of two cranes will work each end of the ship in a coordinated effort. Each crane follows these steps in sequence for each hatch:
- Discharges all the containers on the hatch covers.
- Removes hatch covers.
- Discharges all containers from one cell.
- While discharging the next cell, back-loads the empty cell at the same time.
- Repeats all of the previous steps until all cells of that hatch are completed.
- Replaces hatch covers.
- Back-loads containers on hatch covers.
The operating terminal service company must maintain records of the stacking areas. These records give the specific location of each container within the terminal. Also, as each container comes off the ship, a predetermined storage slot must be known. The actual space (numbers of clusters) required per ship berth (terminal service company) depends mostly on the average dwell time of containers in the terminal. Potential bottlenecks in a marine terminal are as follows:
- The dwell time of containers.
- Frustrated containers.
- Processing of containers at entrances and/or exits.
- Stuffing and/or unstuffing of containers.
- Cleaning and/or maintenance of containers.
- Method for container accountability.
- Vehicle delay and congestion.
Marshaling Area Clearance Operations
This operation ensures containers flow rapidly and uniformly between dockside and the hinterland. To minimize terminal congestion and work stoppages, marshaling area clearance operations are tailored to port unload and/or back-load output. An inbound container should not remain in the marshaling area longer than 24 hours. This also holds true for retrograde containers, provided a containership is available for back-loading. The normal procedure in clearance operations is to designate specific medium truck units to support a specific container unload and/or back-load operation.
The following paragraphs discuss motor transport requirements for marshaling area clearance support of one terminal service company operation. In all cases, medium truck units operate around the clock (two shifts) with 75 percent equipment availability. The terminal service company unloads and, at the same time, back-loads 300 containers per day (two 10-hour shifts). Ideally, inbound containers should be cleared within 24 hours. If this is the case, a minimum of 300 containers per day must be cleared from the marshaling area. (For planning purposes, it is assumed that for each container moved from the marshaling area a retrograde container is returned.) Refer to FM 55-20 for clearance of the terminal by rail and FM 55-30 for clearance of the terminal by highway.
The traffic patterns within the terminal must be designed to support the cranes servicing a ship (see Figure 6-17). Traffic patterns should be counterclockwise: up one side of the cluster when dropping off a container and down the other side when picking up a container.
A HHC, transportation terminal battalion (TOE 55-816L) provides the basic operating HQ for theater terminal operations. It is the normal command element for each two-to four-ship marine terminal.
If it is a two-ship operation, a terminal battalion would operate the terminal. The battalion operations officer supervises consolidated battalion operations for documentation, inventory, and control functions. The battalion also controls operations of areas such as stowing and/or unstowing, inspection, maintenance and repair activities, cleaning and decontamination, equipment parking, and security at battalion level. Thus the terminal service companies can devote their efforts to container handling. Figure 6-18 is a suggested design for security storage in a container marshaling yard.
Container movement by rail is used wherever possible. Rail presents a mass movement capability with little interference from weather or refugee traffic. Except for inland waterway, rail is the most economical mode for moving Army containers. Figure 6-19 presents a procedure for marshaling, loading, and/or unloading containers for a rail movement when the rail facilities are not a part of or adjacent to the marshaling yard.
The commander of an overseas port is responsible, through the operations officer, for operating the port's container marshaling yard. The operation may be keyed to automated documentation procedures or, if automated data processing equipment is not available, to manual procedures.
For import cargo, the shipping port transceiver an advance manifest to the receiving port (TO). Upon receipt of the advance manifest, the receiving port sets up files for preparing documentation. These files include hatch summaries, PCCPs, CDIs, and TCMDs. Hatch summaries, preprinted from the advance manifest, provide the operator with advance notice of the types (cargo or refrigerated) by size and quantity of incoming containers, movement priorities, and ultimate destinations. This information (in conjunction with the PCCPs) permits the operations officer to preplan marshaling yard space requirements and to predetermine where each off-loaded container will be stacked. This is particularly important in the planning of onward movement of outsize and/or overweight cargo. Figure 6-20 shows a system for identifying containers by number and location within the marshaling yard.
In Figures 6-8 through 6-17 the container clusters are lettered. Within each cluster, the rows are lettered. The marshaling yard and the cluster and row designators are combined to form a three-character alpha designator acceptable to the data processing system. Thus, container X acquires the designator of A-B-C: it is in row C, of cluster B, of marshaling yard A. This designator may be card-punched and entered in the tape of the CPU. Marrying up each container number with its location designator in the computer memory provides a computerized container yard inventory. When a container moves out of the yard or is relocated within the yard, the change is entered in the CPU by punch card. Thus, the inventory remains current The computerized inventory should be verified daily by a physical inventory. If desired, a locally fabricated visual display board may back up the computerized inventory.
Since the stack location of the container is planned, the cargo checker can receive a printout for the containers he will be tallying. Using this as containers are unloaded from the ship, he can direct the yard transporter to the designated stacking area. Radio communication between the cargo checker and the marshaling yard is the only way to ensure adequate control of the operation, especially in a large yard or in a highly flooded situation. If computer equipment is not available, a visual display board of the stacking area is kept by operations to provide container identification and location. A manual system requires appropriate internal communications.
Cargo Disposition Instructions
These are used as a consignee advance notification document. Based on the CDI, the port's servicing MCT coordinates with the consignee's MCT to ensure that the consignee can receive the shipment. They arrange delivery dates and transportation to move containers from the marshaling area to final destination.
When a retrograde container enters the marshaling yard, the container transporter driver presents the TCMD at the entry point and has the container inspected. He gets a receipted copy of the TCMD (proof of the delivery) and is directed to the point where the container is to be unloaded. (He also gets a TCMD for the container that he will pick up for movement out of the yard.) A TCMD is required each time cargo is moved from the AOR. No container can be moved out of the marshaling yard exit or entry point without proper documentation and inspection. The container, the container transporter, and the container seal numbers must all agree with those shown on the TCMD. If not, the container will not be moved until proper documentation is prepared. When the container departs the marshaling yard, a copy of the TCMD is retained for entry into the CPU. It must be retained to show that the container has been shipped to the consignee and to update the computerized marshaling yard inventory.
Losses under containerization are growing. They have become of major concern to industry and government alike.
Cargo Theft and Pilferage
Reduction of cargo theft and pilferage is a significant benefit of containerization. Compared to losses suffered in break-bulk operations, the reduction is indeed noteworthy.
Inbound/Outbound Traffic Control
Strict control of incoming and outgoing traffic is a key factor in marshaling yard security. Restricting vehicular traffic entering or exiting the container stacking area to container transport equipment, MHE, and mobile scanning equipment is essential. Also essential is the establishment of a single control point (gate) for vehicular traffic entering or exiting the container stacking area. US military personnel assisted, as necessary, by foreign national police and/or interpreters, man and operate this point. Military personnel assisted, as necessary, by foreign national police and/or interpreters should operate a separate gate for pedestrian traffic. Surveillance and control functions of the vehicular control point include the following:
- Preventing entry of unauthorized vehicles.
- Inspecting inbound and outbound containers.
This is a thorough physical inspection including container condition; presence and condition of container seal and/or lock; evidence of illegal entry (such as tampering with or removal of door hinges); and, particularly for outbound containers, stolen items (look on top of and under the container and inspect the transporter cab).
- Verifying documentation for correctness, completeness, and legibility. (Ensure that transporter, container, and container seal numbers match those shown on the TCMD.)
- Operating scanning equipment. (If there is no scanning capability, container numbers are reported manually to operations so that the yard inventory may be updated.)
- For outbound containers, entering the departure time and date on the TCMD and retaining copy for terminal files.
- For inbound containers, signing one copy of the TCMD for the transporter operator to keep as a delivery receipt.
Surveillance and control functions of the pedestrian control point include the following:
- Permitting only authorized personnel to enter the container marshaling area (mainly concerns foreign national contract operators and other indigenous personnel).
- Maintaining, controlling, and safeguarding the pass system for foreign national personnel authorized to be in the area.
Security of the marshaling yard perimeter backs up gate security in keeping unauthorized persons out. Such persons may engage in sabotage, petty theft, and large-scale theft operations and may establish inside contacts with foreign nationals or other persons working in the yard. While it may not be possible to fence the entire yard perimeter, the security (sensitive, classified, or high-dollar-value cargo) area should be fenced with its own military-guarded gate and MP control. Perimeter defense measures may include one or a combination of the following:
- Chain-type fencing topped by three strands of barbed wire. (Inspect fence daily to ensure there are no holes or breaks.)
- Concertina wire.
- Use of a sensor, when feasible.
- In LOTS, mined strips on the land side.
- Use of patrols.
Container Transporter Operator
Drivers of the line-haul and local-haul container transporters are required to remain in the cab of their truck when operating within the container stacking area.
As already stated, security cargo should be stored separately from other cargo and should have its own secured area. Whenever possible, security cargo should also be unloaded from the ship during daylight hours. If possible, MP security personnel should observe unloading operations.
No containers are allowed to move through the marshaling yard entry or exit (control) point without a valid and legible TCMD.
When the MCT determines that a container is to be forwarded to the consignee, it informs the documentation section and the control point. The MCT gives the date of the movement, the container number, and the name of the consignee to the documentation section. The documentation section then prepares the TCMD and informs the MCT and the control points of the actions, giving the container number, the TCN, and the transporter number. These coordinating procedures prevent removal (either accidentally or purposely) of containerized cargo from the yard. At the gate, the container number is verified against the information provided by the movement and the documentation sections. The container, seal, and transporter numbers are verified for agreement with those entered on the TCMD. The container's seal is examined for breakage or evidence of tampering. Finally, before the container is released, it is inspected for damage. When the control people release the container, they notify the MCT. It in turn notifies the consignee MCT that shipment has been made.
A TCMD must also accompany retrograde containers. After control people verify TCMD entries (such as container and seal numbers) and inspect the container, they give the driver a receipted copy of the TCMD. They also give directions to where the container is to be unloaded.
Verification of Cargo Arrival
Upon receipt of the container, the consignee returns a copy of the TCMD to the shipping terminal activity. The TCMD contains the consignee signature, date of receipt, and condition of cargo, container, and seal.
Normally TCMDs are not accountable documents. However, local procedure may serially number TCMDs. This is an excellent procedure to deter their use in organized thievery. Regardless, blank TCMDs should be secured. One individual should be responsible for safeguarding and issuing them.
A container seal is a device applied to the container door fastening. It indicates whether the door has been opened or the fastening tampered with, and if so, at what point in the movement system it happened. Seals are serially numbered to help identify the person who applied the seal and to provide a means of control. Failing to strictly account for seals from receipt to application defeats their purpose (to pinpoint unauthorized entry into containers). Container seal control and accountability are promoted by the following procedures:
- Maintain a record, by serial number, of seals received by the port operations officer and issued to authorized personnel for applying to containers.
- Store seals under lock. Designate one person to be responsible for the safekeeping, issuing, and recordkeeping of seals applied at the port.
- Designate specific persons (keep the number to a minimum) on each shift to apply seals and enter the serial number of the seal on the TCMD.
- Conduct periodic inventory of seals.
- Apply seals as soon as the container has been stuffed and as soon as a loaded (unsealed or improperly sealed) container is detected.
- Supervise the seal application. Failure to supervise or allow a yard hustler to move an unsealed container to the stacking area offers an opportunity for pilferage of cargo before seals are applied. It also affords the opportunity to apply a bogus seal, to break the seal later, and to remove cargo and then apply a legitimate seal.
Computing Container Space Requirements
The following is a sample problem for computing container space requirements in a marshaling area: your unit has been tasked to operate a container terminal with a total marshaling area of 830 feet wide and 886 feet long. The area must be designed for a one-ship operation using the sideloader in the stacking clusters.
To satisfy operational requirements, the stacking method must be used to enhance selective extraction. You are to determine the intrinsic capacity of the marshaling area using Figures 6-21 and 6-22. Also use Figures 6-21 and 6-22 to perform the following steps:
Step 1. Layout a plan of the area.
- Draw a rectangle representing the area.
- Draw in surrounding intersecting aisles.
- Draw in through intersecting aisles.
- Determine measurements of clusters.
Step 2. Determine the number of 20-foot containers in each row.
- Determine how many 20-foot containers will fit into each row, by dividing 340 by 20.5 (.5 equals halffoot space allowed between containers for working room). This equals 16.58 containers per row. Any fraction is not counted a container; therefore, .58 is lost space (.58 x 20.5 = 11.89 feet). To provide more aisle space, move containers 10 feet to the left or right.
- Stack containers (turret stacking) in two-/two-/one-high sequence in any given row. Every three ground slots have a five-container capacity. To determine the number of containers in a row, divide the number of columns by 3. Multiply that product by 5. If 3 does not divide evenly into the number of columns, the remainder is multiplied by 2 and added to the previous product. For example:
16 columns divided by 3 = 5 (with a remainder of 1)
5 x 5 = 25
1 (remainder) x 2 = 2
25 + 2 = intrinsic capacity of 27 TEUs per row in areas A and B
Add the 10 feet of unused space to areas C and D. Repeat the calculation set forth in the previous paragraphs. For example:
350 divided by 20.5 = 17.073 containers per row
073 x 20.5 = 1.5 feet
17 divided by 3 = 5 (with a remainder of 2)
5 x 5 = 25 containers
2 (remainder) x 2 = 4
25 + 4 = 29 TEUs per row with 1.5 feet of unused space in areas C and D
Step 3. Determine the number of rows.
- Stacking 8-foot wide containers side by side in double rows with a rolling space of .5 feet between the rows would occupy 16.5 feet. The sideloader requires a 15-foot working aisle. So in every 30.5 feet are stacked two rows. The length of this area is 368 feet, divided by 30.5 feet equals 11.65 or 11 double rows, with 21 feet remaining between a working aisle and an intersecting aisle.
- Using the intersecting aisle to work from would allow 16.5 feet of the 21 to be used for a further double row, for a total of 12 double rows.
Each double row in A and B has 64 TEUs. Each double row in C and D has 68 TEUs. A and B each contain 64 TEUs multiplied by 12 double rows. This equals 646 TEUs in each quadrant. A and B together contain 1,296 TEUs. C and D each contain 68 TEUs multiplied by 12 rows. This equals 696 TEUs in each quadrant. C and D together contain 1,392 TEUs. A and B (1,296 TEUs) plus C and D (1,392 TEUs) equals an intrinsic capacity of 2,688 TEUs. The optimum operating capacity is 66 percent of 2,688 or 1,478 TEUs.
|Join the GlobalSecurity.org mailing list|