What to do?


This page is divided into two parts. The first part contains all sorts of information on how to use the site. It starts with the instructions on how to go through the site, subsequently other (more detailed) information on how to use the site is given. For example, the purpose of the site, the importance of the problem, the target group, the required information, the contents of the whole site and the route through the site are described.

The other part of this page contains information per topic. The explanations given here, mainly contain an exemplification on terms, which are used in the questions at the left side of the screen.

How to use this site?

Instructions

The main purpose of this site is to let you find out how to make your warehouse more efficient by comparing scenarios. All information to support this purpose can be found by clicking on the blue buttons at the left side of the screen.

'Examples'-button

To know what possibilities this site can offer you, a page with examples is made. This page can be viewed by clicking on the blue 'Examples'-button at the left side of the screen. The (fixed) specifications on two examples, namely one routing and one batching example, are presented at the right side. The first example is the routing example (click on the 'Routing example'-button). The specifications of the table are now visualized in the warehouse at the right side. By clicking on the 'locations'-button at the left side, the locations of the items, that are to be picked, become black. These items can be picked with the use of four different routing strategies, namely the S-Shape routing strategy, the Largest Gap routing strategy, the Combined routing strategy or the Optimal routing strategy. By clicking on these buttons the route through the warehouse can be viewed. At the left side of the screen the total travel distance in meters as well as the time it takes to pick the order in seconds is given. By clicking on the 'Self Experiment'-button you can make your own route.

The batching example not only shows you the routes through the warehouse, but also what the effects of combinating of orders can be. For more information on how to use the examples page, read the instructions beneath the warehouse.

'Calc. order picking time'-button

With this button you can start the calculations, provided you have installed the Shockwave for Authorware plug-in. This plug-in is needed to show the results of the simulations. If you do not have this plug-in, you can download it. Just click on the Authorware-button that automatically appears at the left side of the screen after loading this page.

If you want to calculate the orderpicking time for a certain scenario, you have to fill in the questions (about the layout of your warehouse and the storage strategy) on the left side of the screen. But not after you have chosen your type of warehouse. To guide you through the questions, an explanation on the terms and questions can be found at the right side of the screen. Some terms also have a detailed explanation, which can be found by clicking on the links.

After all questions, which already have default values, are answered, you can choose the routing strategy you use in your warehouse, or click on (more than) one strategy to see the differences between the routing strategies. In the next screen, the simulation can be run. The more runs you choose, the more accurate your answer will be, but it will also take longer to obtain the results. The results are shown on the right screen as well as the answers you have given to the questions.

'References'-button

References on this subject can be found by clicking on the 'References'-button.

More detailed information on how to use this site can be found below.

About this site

This site is part of the Stichting Logistica website and is developed in association with the Erasmus University Rotterdam. The authors of the site, which are all associated with the Erasmus University Rotterdam are: Prof. Dr. Ir. M.B.M. de Koster, professor of Logistics and Operations Management, M.H. Mekern, Scientific Software Developer, D. Oudijk, student and Dr. K.J. Roodbergen.

Purpose

The main purpose of this site is to give the user an easy-to-use tool to discover how the orders in his/her warehouse have to be picked in order to reach more efficiency. It is possible to calculate the orderpicking time with the use of different routing methods for different scenarios with regard to

  • warehouse type (wide aisle pallet, narrow aisle pallet or shelf area)
  • layout (number of cross aisles, aisle length, number of aisles, etc.)
  • storage strategy (ABC-1, ABC-2, random)
  • orderpicking pattern (number of orders, lines per order)
  • material handling equipment (speed, capacity)

By varying the layout, number of aisles, storage strategy and routing strategies, you can determine what the best orderpicking warehouse design is for your particular situation.At the moment it is not possible to find out what the results of the batching of (some of the) orders is. Information on the batching process however can already be found by clicking here. Possibly this option can offered in the future.

Structure of this site

The different parts of this site can be entered from the main menu at the left side of the screen by clicking on one of the buttons presented there. It is best to read the instructions at this help page, before you want to use the site. The button containing the word 'Examples' will lead the user to two different examples of warehouses. The button 'Calc. order picking time' leads you to the pages where you can discover how efficient your warehouse is. A large list of references on this subject can be found by clicking on the 'References'-button.

The button 'warehousing at Erasmus Univ' will lead the user to the pages of the Erasmus University Rotterdam, department Management of Technology and Innovation. Here further links can be found to suppliers of material handling equipment, consultancy agencies, warehouse management software suppliers and research related topics can be find.

For whom?

This site is particularly of use for people who are responsible for the orderpicking process in a warehouse. With the use of this site it is easy to discover what changes in the design of the orderpicking warehouse have to be made in order to increase efficiency.

Importance of the problem

In warehouses and distribution centres, products have to be picked from specified storage locations on the basis of customer orders. In general, the orderpicking process is the most laborious of all warehouse processes. It may consume as much as 60% of all labour activities in the warehouse (cf. Drury [1988]). Especially in distribution environments, the pick process is usually carried out under time constraints. Orders tend, more and more, to arrive late and have to be shipped the same day at pre-fixed departure times per destination (a hub, a group of shops, a geographical area or a customer). This leads to peak loadings and an on-going pressure to carry out the orderpicking process as efficient as possible. One of the ways to achieve savings on orderpickers and equipment is by optimizing orderpicking routes. Depending on the number of items to be picked, reductions on the total walking distance in a warehouse can be as much as 40% (De Koster et al. [1997]).

What information is needed?

To find out how long it takes to pick all items, several questions have to be answered. These questions are grouped into different categories in four screens. The first screen contains questions which relate to the layout of the warehouse. Here, questions concerning the length and the width of the aisles, the number of aisles, but also the speed in- and outside the aisles are posed. The second screen contains questions which relate to the storage of the items; the storage strategy, the number of lines per order, the administration time and the time to pick a line. The third screen only contains the possibility to choose the routing strategy after which the number of (simulation-)runs has to be entered (screen 4). In each simulation run, a random warehouse instance is generated and the orderpicking time is calculated. In the results screen the mean and standard deviation of the orderpicking time per order is given.

Explanation per topic

An explanation of each of these terms can be found by clicking on them.

A B C D E F H I L M N O P R S T W Z

A

ABC storage strategy (short)
ABC storage strategy (long)
Additional time to change aisles
Administration time
Aisle length
Aisle number

B

Batching
Batching examples

C

Change aisles
Clarke and Wright
Combined heuristic (short)
Combined heuristic (long)
Cross aisle

D

Depot location (short)
Depot location (long)
Distance between aisles

E

Examples of orders

F

First come, first served

H

(Material) Handling equipment
Heuristic (routing)

I

Instructions (on how to use this site)

L

Largest Gap (short)
Largest Gap (long)
Layout of the warehouse
Layout of the storage zones (short)
Layout of the storage zones (long)
Lines per order
Location of depot (short)
Location of depot (long)

M

Material handling equipment

N

Narrow aisle pallet warehouse (short)
Narrow aisle pallet warehouse (long)
Number of aisles

O

Optimal routing algorithm (short)
Optimal routing algorithm (long)
Order examples
Orderpicking process

P

Percentage of picks

R

Random storage strategy (short)
Random storage strategy (long)
Rear end
References
Route
Routing examples
Routing strategy

S

Savings algorithm
Seed algorithm
Shelf area warehouse (short)
Shelf area warehouse (long)
Simulate
Speed in- or outside the aisles (short)
Speed in -or outside the aisles (long)
S-Shape (short)
S-Shape (long)
Storage strategy

T

Time to change aisles
(Administration) Time
Time to pick a line

W

Warehouses (types)
Warehouse layout
Wide aisle pallet warehouse (short)
Wide aisle pallet warehouse (long)
Width of aisle

Z

Zones