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How Much Do You Know About Container Terminal Slot Positions?

Published:2026-10-21 02:35
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Using a container terminal with a capacity of tens of millions of TEUs as an example, let's talk about "container slots" in a very vivid and easy-to-understand way.

 

Before we dive into "container slots," let's look at a small question first.

 
　　Below, a formula is used to explain berth utilization and berth occupancy. Although we've highlighted the key points, some diligent and inquisitive friends are still not satisfied and ask: What does this "berthing gap coefficient" mean?

 

 

Let's look at an example:

 

　　Think of the underground parking garage in your residential community. Typically, parking spaces are wider than the cars themselves to leave necessary clearance between vehicles, so your car can enter and exit at any time without scraping adjacent vehicles.
 
　　The rows of parking spaces are analogous to our terminal berths (see the image below), and the parked cars are like container ships berthed for operations. This "berth clearance factor" is set precisely to reserve space for vessels to maneuver in and out of berths, and is generally a fixed value of 1.1.
 
 
　　Since this gap occupancy is a necessary condition for vessel berthing operations, it must be included when calculating berth utilization and occupancy rates. Now, if you look back at the formula above, does it make more sense?

 

Alright, let's get down to business and dive into the main topic~

 

　　Working at a "ten-million TEU" single container terminal, you've surely seen scenes like this many times:

　　And there are also scenes like this:

 

　　While marveling at the spectacular view, do you also find it overwhelmingly dense? Do you know exactly how many containers are in the Dabeisan yard? Let me give you a few figures:
 
　　 The Dabei San container yard covers an area of 1.837 million square meters, with a stacking capacity of 230,000 TEU and an average on-site inventory of around 150,000 TEU. If all these containers were lined up end to end and you drove along the top of them, it would take you about nine hours! The reason these container "building blocks" can be arranged so neatly is a coding system that gives each one a designated "home."
 
　　 In other words, within the container terminal yard, every container has its own unique ID, known as the "slot position."

 

 
　　 It is precisely by using this "ID" that our controllers and gantry crane operators can accurately locate a specific container among thousands of stacks for directing and lifting operations.
If you're still feeling a bit fuzzy on the details, let me walk you through it in five steps—like putting an elephant into a fridge. Watch closely~

Step 1: Divide the entire yard into "Areas"

 

Based on the berth sequence, each berth corresponds to one area. For example, Berth 1 corresponds to Area 1, Berth 2 to Area 2, and so on. Here's an illustration:

 

Step 2: Each area is further divided into "Blocks"

 

For instance, in Area 5, following the order from seaside to landside, the blocks are labeled 5-1, 5-2, and so on. If you reach the 10th block and there are still more, continue with 5-A, 5-B, etc.

Step 3: Each block is further divided into "Bays"

 

　　The English term is BAY, which corresponds to the bay slots on a vessel. By convention, odd numbers indicate the placement of 20-foot containers, while even numbers indicate the placement of 40-foot containers. Text can be abstract, so let’s look at an illustration:

　　To help you understand, we’ve marked the actual stacking bay positions of this container block with numbers in red circles. Did you get it?

Step 4: Each bay is further divided into "Rows"

 

　　Each bay typically has 6 rows, numbered 1, 2, 3, 4, 5, and 6 starting from the lane side. Let’s look at a single bay of containers:

 

Step 5: Each row is further divided into "Tiers"

 

　　In English, it's called "TIER," usually consisting of 4 to 5 layers. From bottom to top, they are numbered 1, 2, 3, 4... Take another look at the same bay:

 

How’s that? Got it? Here’s another diagram to help you review and reinforce:

 

 

　　 Alright, by combining these five steps, you can easily state a container's slot position. After sorting it out like this, doesn't it actually seem quite simple~

 

　　 Do you know why some containers are stacked tightly together like this?

 

　　And why do some have a gap left like this?

 

It's quite simple: generally, containers stacked tightly together are empty ones; those stacked with gaps between them are laden containers.
 

Let's reinforce this!!!!

1
 
Row (Line)

 

 
 

There are two ways to express this:

(1) Numbered sequentially from bow to stern using natural numbers: 01, 02, 03...

(2) Numbered from bow to stern using odd or even natural numbers.

When loading 20ft containers, use odd-numbered sequence: 01, 03, 05, 07...

When loading 40ft containers, use even-numbered sequence: 02, 06, 10, 14...

 
 
2
 
Bay Number

 
 

There are two numbering methods:

(1) Numbered sequentially from starboard to port using natural numbers: 01, 02, 03...

(2) Based on the centerline, odd numbers are assigned to starboard and even numbers to port in sequential order.

When the total number of rows is odd, the cell on the centerline is assigned row number 00, starboard-side cells are numbered 01, 03, 05, 07..., and port-side cells are numbered 02, 04, 06, 08...

When the total number of rows is even, there is no cell on the centerline. Starboard or port cells follow the same numbering pattern, using 01, 03, 05, 07... or 02, 04, 06, 08 respectively.

 

3
 
Tier Number

 
 

　　There are two representation methods:

Divided into hold tier number and deck tier number

(1) Method 1:

Hold tier numbers are based on the lowest tier in the hold, and are indicated from bottom to top using sequential numbers H1, H2, H3, etc.

Deck tier numbers are based on the deck, and are indicated from bottom to top using sequential numbers D1, D2, D3, etc.

(2) Method 2:

Hold tier numbers are based on the lowest tier in the hold, and are indicated from bottom to top using sequential numbers 02, 04, 06, etc.

Deck tier numbers are based on the deck, and are conventionally indicated from bottom to top using sequential numbers 80, 82, 84, etc.

 
 
4
 
Quick Q&A

 

 

Q: Where are the three container slots 531212, 540788, and 551184? Have you found them?

 

 
 
 

Source: Cang哪儿云

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