Distribution centers: types, cross-docking, picking and location

30/10/2026 •0•0

What distribution centers do, the types of warehouses, how cross-docking and picking work, and how to choose a DC location using the center-of-gravity method.

作者Leon

翻訳者Editorial

改訂者Editorial

Introduction

Although it is often preferable to avoid it, materials sometimes need to be stored, even if only briefly. Storage might mean a medicine cabinet in a small hospital pharmacy or a warehouse covering tens of thousands of square meters and supplying stores across an entire country. In manufacturing, warehouses store raw materials, supplies, work in progress and finished goods. In retail and distribution, the main warehouse is usually called a distribution center (DC).

The previous lesson covered warehouse operations: receiving, storage, inventory control, stocktaking and documentation. Here, the focus is on the warehouse as a node in the logistics network: what it does, the different types, how cross-docking and order picking work, and where to locate it. Managing inbound flows, internal movement and outbound flows is all part of the same job: managing storage means managing the physical movement of goods.

Why Store Goods?

Storage costs money: space, staff, equipment and capital tied up in inventory. So why not produce goods and deliver them directly? Because storage bridges the gap between production and consumption, making it possible to:

Reduce transportation costs by consolidating shipments. A full truck from a factory to a DC, followed by short deliveries from the DC to stores, usually costs less than many long, half-empty trips from the factory to each store.
Improve production efficiency through a steady flow of supplies and economical production runs, even when demand fluctuates.
Serve customers quickly by keeping products close to them and shortening delivery times.
Obtain quantity discounts on purchases (see the lesson on economic order quantity).
Protect against uncertainty in demand and delivery times (see safety stock in the lesson on lead time).

Warehouse Activities

Managing storage and the physical movement of goods involves:

Receiving materials, including unloading vehicles when required by the contract.
Identifying materials.
Moving materials from receiving to storage areas.
Storing the goods.
Tracking the physical location of each item.
Picking items for each order and consolidating shipments for dispatch.
Dispatching goods: checking, loading and shipping them on vehicles.
General management of staff, facilities, equipment and maintenance.
Operating the information system and recording every inbound and outbound movement.

To keep costs down, a warehouse should have enough capacity to meet its actual storage needs and a layout that allows goods to move quickly from receiving through storage to dispatch. Three factors have the greatest effect on productivity:

Effective use of material-handling and transport equipment.
Qualified, trained staff.
Effective use of cubic space: making use of height, not just floor area.

Those factors, in turn, depend on three others: a reliable system for tracking storage locations (the location coding covered in the warehouse lesson), packaging suited to handling and storage, and the form in which goods are received and dispatched (loose, palletized or containerized).

A company has 5 factories and 300 stores. Each factory currently delivers directly to every store, using trucks that are almost always half-empty. What is the primary benefit of adding a DC between the factories and stores?

Answer: Lower transportation costs through consolidated shipments: full trucks to the DC and short deliveries from there — the scenario describes exactly the problem of long trips carrying partial loads. The DC does not eliminate safety stock; instead, that stock is held there.

Types of Warehouse

Lambert and Stock classify warehouses into three broad categories according to the goods they handle:

Manufacturing support warehouses store raw materials and supplies from multiple suppliers for use at a factory.
Mixed warehouses store both raw materials and supplies and finished goods destined for customers. They are common in manufacturing.
Consolidation warehouses receive products from multiple suppliers and assemble mixed shipments to match each customer's order. A large wholesaler is a classic example: it receives goods from hundreds of manufacturers and sends each customer a shipment containing some of each.

The choice depends on the company's strategy. Distributors almost always use consolidation warehouses, where two of the most widely studied warehouse operations take place: cross-docking and picking.

Other Models on the Rise

Retail distribution center: supplies a chain's stores, receiving large shipments and dispatching smaller ones several times a week.
E-commerce fulfillment center: picks orders containing just a few items for thousands of consumers each day. The challenge shifts from moving pallets to picking individual items quickly and accurately.
Dark store: a store or small urban warehouse closed to the public and used solely to pick orders for rapid delivery. It addresses the last-mile challenge discussed in the lesson on intermodality and trends.
Third-party warehouse and logistics provider: rather than run its own warehouse, a company contracts with a third party for space and operations, paying per pallet position, movement or order. This replaces a fixed investment with a variable cost, following the same make-or-buy logic covered in the lesson on supplier selection.

Cross-Docking and Picking

Cross-Docking

In cross-docking, shipments arrive from multiple suppliers, are sorted and combined by destination, and leave on other vehicles within a few hours, without being stored. The warehouse becomes a transfer point. It works well when:

demand is stable and predictable;
suppliers deliver at the agreed time with reliable labels;
an information system identifies each package's destination before the truck arrives.

The benefits can be substantial: less inventory, less handling and less space. So can the risk: if a supplier is late, the outbound truck must wait or leave without a complete load. Many operations therefore use a mix of cross-docking and conventional storage.

Picking (Order Picking)

Picking means retrieving the quantities of each item a customer has ordered from their storage locations. In many DCs, it accounts for most labor, and workers spend much of their time walking between locations. The main approaches are:

By order: one picker completes an entire order from start to finish. It is simple, but involves a lot of walking.
By batch: a picker collects items for several orders in one trip, then sorts them by order.
By zone: each picker covers one area, and an order passes from zone to zone (or each zone picks its portion and the items are brought together at the end).
By wave: orders are released in scheduled windows aligned with vehicle departures.

Technology helps reduce errors and travel time: handheld barcode scanners, lights showing the location and quantity to pick (pick-to-light), voice instructions and, in more automated warehouses, goods-to-person systems, in which robots bring shelving units to pickers rather than pickers going to the shelves. The best-known example is the robots developed by Kiva Systems, which Amazon acquired in 2012 and which became the basis for Amazon Robotics.

The video above shows Natura's distribution center in São Paulo. Its automated system picks orders containing small quantities, as is typical for a company that sells through resellers and needs to assemble thousands of different boxes each day.

Every day, a wholesaler receives scheduled truck deliveries from 40 suppliers. Products are already labeled by destination store, and store demand is stable. Which operation would do the most to reduce inventory and handling?

Answer: Cross-docking — with on-time deliveries, destination labels and stable demand, shipments can be sorted, combined and dispatched without being stored. Picking by order requires stored inventory and is more labor-intensive.

How Many DCs, and Where?

More DCs put products closer to customers and shorten deliveries, but they also increase inventory (each DC needs its own safety stock), rent and staffing costs, as well as the cost of transporting goods from factories to DCs. Fewer DCs have the opposite effect. The decision involves balancing transportation costs, inventory and facility costs, and the delivery times the market demands. Companies selling throughout Brazil often have one DC per major region; regional companies may have just one.

A simple method offers a useful starting point for choosing a DC location: the center of gravity. Plot each customer (or demand region) on a plane with x and y coordinates, then calculate the average coordinates weighted by volume:

X = Σ (volume × x) ÷ Σ volume
Y = Σ (volume × y) ÷ Σ volume

Example

A distributor serves five customers:

Customer	x (km)	y (km)	Volume (t/month)	volume × x	volume × y
A	20	80	300	6.000	24.000
B	60	90	150	9.000	13.500
C	90	40	250	22.500	10.000
D	40	20	200	8.000	4.000
E	70	60	100	7.000	6.000
Total			1.000	52.500	57.500

X = 52.500 ÷ 1.000 = 52,5 km and Y = 57.500 ÷ 1.000 = 57,5 km.

The five customers, with circle size proportional to volume, and the calculated center of gravity

With the DC at the center of gravity, the sum of volume × straight-line distance is about 36.900 t·km per month. If the DC were located next to the largest customer (A), it would be about 44.400 t·km, 20% more. The center of gravity is not quite the point that minimizes total distance (an iterative calculation finds the optimum around 56,2 and 59,0, at 36.760 t·km, just 0,3% better), but a calculation that can be done by hand gets close.

It is a starting point, not a final answer. The next questions cannot be answered from the map alone: Is there a good road nearby? Is land or a warehouse available, and at what price? What is the state's tax burden (a major factor in DC location decisions in Brazil)? Is labor available? The calculated point might fall in the middle of a river.

Two customers are located at x = 10 km (400 t/month) and x = 70 km (200 t/month), both at y = 0. Where is the center of gravity on the x-axis?

Answer: 30 km — X = (400 × 10 + 200 × 70) ÷ 600 = 18.000 ÷ 600 = 30. The 40 km answer is the simple average, which ignores the fact that the first customer accounts for twice the volume and therefore pulls the DC closer.

Physical Movement

Every time an item is picked up, moved and put down somewhere else, it takes time and risks damage without adding anything to the product. The general rule for material handling is therefore move less, and move better:

Eliminate unnecessary movements and combine steps (for example, check goods at their storage location).
Move unitized loads (pallets, containers) rather than loose packages.
Keep goods moving along a clear path (receiving on one side and dispatch on the other, or a U-shaped flow with docks on the same side), without crossing paths or backtracking.
Use gravity where possible (flow racks, ramps).
Make use of height with suitable equipment.
Place fast-moving items near dispatch.
Prioritize ergonomics and safety: mark aisles and keep pedestrians separate from forklifts.

Material-handling and storage equipment, along with warehouse layout techniques, are the subject of the next lesson, on equipment and optimizing warehouse operations.

Key Points

Storage helps consolidate shipments, stabilize production, serve customers quickly, buy in quantity and protect against uncertainty.
Warehouses may support manufacturing, handle both inputs and finished goods, or consolidate shipments; other models now include retail and e-commerce DCs, dark stores and third-party logistics providers.
Cross-docking sorts and combines shipments without storing them; picking retrieves quantities for orders by order, batch, zone or wave.
More DCs shorten delivery times and reduce outbound freight costs, but increase inventory and fixed costs.
The center of gravity is the volume-weighted average of customer coordinates: a useful first estimate for a location.

Exercises

Easy

1) What is the difference between a warehouse that uses cross-docking and a conventional warehouse?

2) Three customers are located along the same road, all at y = 0: customer 1 at x = 0 km (100 t/month), customer 2 at x = 60 km (200 t/month), and customer 3 at x = 90 km (100 t/month). Where on the road is the center of gravity?

3) Classify each warehouse according to Lambert and Stock (manufacturing support, mixed-use, or consolidation):
a) An automaker’s warehouse stores sheet metal, paint, and components from dozens of suppliers to supply the production line.
b) A wholesaler receives goods from 300 manufacturers and ships each supermarket a load containing some products from each.
c) A furniture factory’s warehouse stores wood and hardware, as well as finished furniture awaiting delivery to customers.

4) Which picking method is described in each case?
a) A picker collects items for 20 orders in a single trip, then sorts them by order.
b) Orders are released in scheduled waves timed to each truck’s departure.
c) Each picker works in one area of the warehouse, and each order passes through several areas.

5) Name three benefits that justify the cost of keeping a warehouse between the factory and the customer.

Challenging Questions

6) A distributor serves four customers:

Customer	x (km)	y (km)	Volume (t/month)
A	10	10	400
B	50	10	200
C	50	50	300
D	10	60	100

a) Calculate the center of gravity.
b) Calculate the sum of volume × straight-line distance with the distribution center at the center of gravity.
c) Compare this with a distribution center located next to customer A, where the sum is about 29.971 t·km per month. What is the percentage saving at the center of gravity?
d) Give two reasons why the calculated location might not be chosen.

7) A company has one distribution center. Total daily demand has a standard deviation of 400 units, replenishment lead time is a constant 4 days, and the company uses z = 1,65. It is considering opening 4 regional distribution centers, each serving a quarter of the market. Regional demand is independent and has the same variability in each region (the daily standard deviation for each region is 400 ÷ √4 = 200 units). Use the formula from the lesson for lead time and safety stock: ES = z × σ × √LT.
a) What is the safety stock with 1 distribution center?
b) What is the total safety stock with 4 distribution centers?
c) If each unit is worth R$ 50 and the annual inventory carrying cost is 25%, what is the annual cost of the additional safety stock?

8) A factory supplies 4 stores in a region 600 km away. Currently, each store receives 8 t per week in a 10 t truck that costs R$ 6,00 per kilometer driven; each store gets one delivery a week (count the outbound trip only). The alternative is to use a 32 t semi-trailer at R$ 9,00 per kilometer to take all 4 stores’ goods to a distribution center in the region. From there, trucks make the deliveries, each covering 40 km (R$ 6,00 per kilometer, outbound trip only). The distribution center costs R$ 3.000 per week.
a) What is the current weekly cost?
b) What would the weekly cost be with the distribution center?
c) What is the maximum weekly cost of the distribution center at which the change would still be worthwhile?

9) At a distribution center, a picker spends 6 minutes traveling through the warehouse per trip and 0,5 minute picking each item. There are 30 orders of 4 items each.
a) How long does picking by order take (one trip per order)?
b) With batch picking, the picker makes 3 trips covering 10 orders each. Each trip takes 9 minutes of travel because it is longer, and sorting takes another 0,2 minute per item. How long does it take?
c) How much time is saved, and where do the savings come from?

10) A pharmacy chain is considering moving all its distribution center operations to cross-docking. Suppliers of brand-name medicines deliver on time and label goods by store, but suppliers of seasonal products (sunscreen, insect repellent) are often late, and sales of those products fluctuate sharply with the weather. What would you recommend? Explain your reasoning.

Answer Key

1) In cross-docking, goods arrive from several suppliers, are sorted and regrouped by destination, and leave on other vehicles within a few hours without being stored: the warehouse is a transfer point. In a conventional warehouse, goods are put into storage locations and only later picked and shipped.

2) X = (100 × 0 + 200 × 60 + 100 × 90) ÷ (100 + 200 + 100) = (0 + 12.000 + 9.000) ÷ 400 = 21.000 ÷ 400 = 52,5 km.

3) a) Manufacturing support: it stores supplies from multiple vendors to keep the factory running.
b) Consolidation: it receives goods from many suppliers and assembles mixed loads for each customer.
c) Mixed-use: it stores both raw materials and finished goods.

4) a) Batch picking.
b) Wave picking.
c) Zone picking.

5) Any three of the following: lower transportation costs through load consolidation; production savings from economical production runs and a steady flow of goods; faster service because products are close to customers; volume discounts on purchases; protection against uncertainty in demand and delivery times.

6) a) Σ volume = 400 + 200 + 300 + 100 = 1.000 t.
Σ (volume × x) = 400 × 10 + 200 × 50 + 300 × 50 + 100 × 10 = 4.000 + 10.000 + 15.000 + 1.000 = 30.000.
Σ (volume × y) = 400 × 10 + 200 × 10 + 300 × 50 + 100 × 60 = 4.000 + 2.000 + 15.000 + 6.000 = 27.000.
X = 30.000 ÷ 1.000 = 30 km; Y = 27.000 ÷ 1.000 = 27 km.
b) Distances from (30; 27): A = √(20² + 17²) = 26,25 km; B = √(20² + 17²) = 26,25 km; C = √(20² + 23²) = 30,48 km; D = √(20² + 33²) = 38,59 km.
Total = 400 × 26,25 + 200 × 26,25 + 300 × 30,48 + 100 × 38,59 = 10.500 + 5.250 + 9.144 + 3.859 ≈ 28.752 t·km per month.
c) Savings = (29.971 − 28.752) ÷ 29.971 ≈ 4,1%; put another way, the total would be about 4,2% higher next to A than at the center of gravity (29.971 ÷ 28.752 = 1,042).
d) For example: no road or suitable access at the location; no available land or warehouse, or high property costs; state taxes; a shortage of workers; or a physical obstacle (a river or protected area).

7) a) ES = 1,65 × 400 × √4 = 1,65 × 400 × 2 = 1.320 units.
b) Each distribution center: 1,65 × 200 × 2 = 660 units; four distribution centers: 4 × 660 = 2.640 units, twice as much. With n equal distribution centers serving independent markets, total safety stock increases in proportion to √n (√4 = 2).
c) Additional stock = 2.640 − 1.320 = 1.320 units; cost = 1.320 × 50 × 0,25 = R$ 16.500 per year.

8) a) Currently: 4 trips × 600 km × R$ 6,00 = R$ 14.400 per week. (The 8 t fit in the 10 t truck, but it travels 20% empty.)
b) With the distribution center: semi-trailer 600 × 9,00 = R$ 5.400; deliveries 4 × 40 × 6,00 = R$ 960; distribution center R$ 3.000. Total = 5.400 + 960 + 3.000 = R$ 9.360 per week (the 4 × 8 t fit exactly in the 32 t semi-trailer).
c) Transportation with the distribution center = 5.400 + 960 = R$ 6.360. The distribution center is worthwhile as long as it costs less than 14.400 − 6.360 = R$ 8.040 per week.

9) a) By order: 30 × (6 + 4 × 0,5) = 30 × 8 = 240 minutes.
b) By batch: each trip = 9 + 40 items × 0,5 + 40 × 0,2 = 9 + 20 + 8 = 37 minutes; 3 trips = 111 minutes.
c) Savings = 240 − 111 = 129 minutes (54%). The savings come from travel time: 30 trips × 6 = 180 minutes falls to 3 × 9 = 27 minutes, more than offsetting the 24 minutes spent sorting (120 items × 0,2). Picking time (120 × 0,5 = 60 minutes) is the same in both cases.

10) Use a mixed operation. Brand-name medicines meet the requirements for cross-docking (on-time delivery, labels by destination, stable demand) and can pass through the dock without being stored. Seasonal products do not: when suppliers are late and demand fluctuates, the outbound truck would either have to wait or leave with an incomplete load. Those items should be stored at the distribution center, with safety stock, and picked for delivery.

この記事はいかがでしたか？

0^%

ユーザー評価 (0)

この記事をシェアしよう！

トピック centro-de-distribuição armazenagem cross-docking picking movimentação logística

ニュースを送信する

Leon

Business Professor and Website Full Stack Programmer

Social

反応

0 コメント

ログインして会話に参加する

最初にコメントする