FACILITY LOCATION

PLANNING
AND ANALYSIS
Learning Objectives
 List some of the main reasons organizations need to
make location decisions.
 Explain why location decisions are important.
 Discuss the options that are available for location
decisions.
 Describe some of the major factors that affect location
decisions.
 Outline the decision process for making these kinds of
decisions.
 Use the techniques presented to solve typical problems.
Need for Location Decisions
Marketing Strategy
Cost of Doing Business
Growth
Depletion of Resources

8-3
 Nature of Location Decisions
Strategic Importance of location decisions
 Long term commitment/costs
 Impact on investments, revenues, and operations
 Supply chains
Objectives of location decisions
 Profit potential
 No single location may be better than others
 Identify several locations from which to choose
Location Options
 Expandexisting facilities
 Add new facilities
 Move

8-4
Factors in Locating Manufacturing Facilities
Favorable Labor Climate
 Proximity to Markets
 Proximity to raw materials sources
 Proximity to Suppliers and Resources
Construction costs, land price
 Proximity to the Parent Company’s Facilities
Factors in Locating Service Facilities
Customer-based factors
Cost-based factors
 Competitor-based factors
 Support systems
Geographic/environmental factors
Business Climate
Communication-based factors
Transportation-based factors
Personal desires of the CEO
Location Screening
Clear responsibilities should be assigned to seek a new
location involving a different site. Location projects
involving a new site usually follow the following
sequence:
Determine the general region or area
Screen communities and select a specific one
Analyze the sites within a specific community and select
one
Plant Location Aspects
1.Selection of Region:
Availability of raw materials
Nearness to source of motive power
Proximity to the market
Availability of transport facilities
Suitability of climate
Plant Location Aspects
2. Selection of Locality:
Supply of labour
Prevailing wage rates
Existence of supplementary of complementary
industries
Banking, credit and communication facilities
Attitude of the people in the locality
Local taxes and bye-laws
Living conditions of workers
Availability of utilities
Plant Location Aspects
3. Selection of Site:
Price of land
Disposal of Effluents
Qualitative Analysis
Step 1: List all the factors that are important, i.e. have an
impact on the location decision.
Step 2: Assign appropriate weights (typically between 0
and 1) to each factor based on the relative importance
of each.
Step 3: Assign a score (typically between 0 and 100) for
each location with respect to each factor identified in
Step 1.
Break-Even Analysis
Break-even analysis computes the amount of goods required to be sold to
just cover costs
Break-even analysis includes fixed and variable costs

Break-even analysis can be used for location analysis especially when the
costs of each location are known

Step 1: For each location, determine the fixed and

variable costs
Step 2: Plot the total costs for each location on one graph
Step 3: Identify ranges of output for which each location
has the lowest total cost
Step 4: Solve algebraically for the break-even points
over the identified ranges
Types of Cost

Costs

Fixed
Variable Costs
Costs

2-13
Variable Costs are…
Expenses that are uniform per unit of output
within a relevant time period
As volume increases, total variable costs
increase

2-14
THERE ARE TWO CATEGORIES OF
VARIABLE COSTS

1. Cost of Goods Sold

2. Other Variable Costs

2-15
Variable Costs – Cost of Goods Sold
For Manufacturer or Provider of Service
 Covers materials, labor and factory overhead
applied directly to production
For Reseller (Wholesaler or Retailer)
 Covers primarily the cost of merchandise

2-16
Other Variable Costs
Expenses not directly tied to production but vary
directly with volume
Examples include:
 Sales commissions, discounts, and delivery
expenses

2-17
Fixed Costs

Expenses that do not fluctuate with output volume

within a relevant time period

They become progressively smaller per unit of output

as volume increases

No matter how large volume becomes, the absolute

size of fixed costs remains unchanged

2-18
THERE ARE TWO CATEGORIES OF
FIXED COSTS

1. Programmed costs
2. Committed costs

2-19
Example -Location Break-Even Analysis
Example -Location Break-Even Analysis
Center of Gravity Method (Single
Facility Location)
This approach requires that the analyst
find the center of gravity of the geographic
area being considered
Computing the Center of Gravity for Matrix
Manufacturing

22
Steps in Center of Gravity Method
Computing the Center of Gravity

Where
Qi = Quantity to be shipped to destination i
xi = x coordinate of destination i
yi = y coordinate of destination i

26
Example

27
Example -Center-of-Gravity
Example -Center-of-Gravity
Multi-Facility Location
How many sites?
Where to locate each?
Capacities?
Which customers assigned to each site?
Which products to stock/produce at each site?
Costs:
transportation, handling, inventory carrying,
production/purchase
facility fixed costs

30
Multiple Centre-of-Gravity Approach
Pre-assign demand points to each facility (i.e.
cluster customers that are closest together).
For each cluster, locate one facility at centre of
gravity.
With facility locations fixed, re-assign
customers to closest facility.
Find centres of gravity for new clusters.
Repeat cluster-assign steps until no further
change.

31
Multiple Centre-of-Gravity Approach -
Example

32
Multiple Centre-of-Gravity Approach -
Example

33
Multiple Centre-of-Gravity Approach -
Example

34
Median Method (Mini-Sum Method)
Step 1: List the existing facilities in non-decreasing
order of the x coordinates.
Step 2: Find the jth x coordinate in the list at which the
cumulative weight equals or exceeds half the total
weight for the first time, i.e.,
Median Method (Cont)
Step 3: Cont... The optimal location of the new
facility is given by the jth x coordinate and the
kth y coordinate identified in Steps 2 and 4,
respectively.
Notes
1. It can be shown that any other x or y coordinate will
not be that of the optimal location’s coordinates
2. The algorithm determines the x and y coordinates of
the facility’s optimal location separately
3. These coordinates could coincide with the x and y
coordinates of two different existing facilities or
possibly one existing facility
Example :
Two high speed copiers are to be located in the fifth floor
of an office complex which houses four departments of
the Social Security Administration. Coordinates of the
centroid of each department as well as the average
number of trips made per day between each department
and the copiers’ yet-to-be-determined location are
known and given in Table below. Assume that travel
originates and ends at the centroid of each department.
Determine the optimal location, i.e., x, y coordinates, for
the copiers.
Prob:
Department X- Y-
coordinate Coordinate Deman
d
1 10 2 6
2 10 10 10
3 8 6 8
4 12 5 4
Solution:
Using the median method, we obtain the following
solution:
Step 1:
Dept.
Dept. xx coordinates
coordinates in
in Weights
Weights Cumulative
Cumulative
## non-decreasing
non-decreasing order
order Weights
Weights
33 88 88 88
11 10
10 66 14
14
22 10
10 10
10 24
24
44 12
12 44 28
28
Solution:
Step 3:
Dept.
Dept. YY coordinates
coordinates in
in Weights
Weights Cumulative
Cumulative
## non-decreasing
non-decreasing order
order Weights
Weights
11 22 66 66
44 55 44 10
10
33 66 88 18
18
22 10
10 10
10 28
28
Solution:
Step 4: Since the third y coordinates in the above list is
where the cumulative weight exceeds half the total
weight of 28/2 = 14, the optimal coordinate is 6. Thus,
the optimal coordinates of the new facility are (10, 6).
Distance measure
The distance measure involved in a facility location
problem is an important element in formulating an
analytical model. There are two ways to measure the
distance between two facilities.
Rectilinear Distance
Euclidean Distance
Rectilinear Distance
When distance between two facilities is measured
along path that is orthogonal to each other, then that
distance is termed as rectilinear distance. Suppose two
facilities are located at points represented by ( X 1 , Y
1 ) and at ( X 2 , Y 2 ) then the rectilinear distance
between the facilities will be :
| X 1 - X 2 | + | Y 1 - Y 2 |
Euclidean distance
When distance is measured along straight-line path
between the two facilities, then that distance is termed
as Euclidean distance. Suppose two facilities are
located at points represented by ( p , q) and at ( r , s )
then the Euclidean distance between the facilities will
be
Euclidean distance= [(p-r) 2 + (q-s) 2]1/2
Example Mini-Max Location
(10, 16)
16
h4 = 11
Find the optimal location of an ambulance
with respect to four (known) possible 14
accident locations which coordinates are
P1=(6,11), P2=(12,5), P3=(14,7), and P4=(10,16).
12
The objective is to minimize the maximum
(6, 11)
distance from the ambulance location to an
10 h1 = 10
accident location and from the accident
(12, 9)
location to its closest hospital. The
distances from the accident locations to 8

their closest hospitals are h1=10, h2=16, (14, 7)

h3=14, and h4=11. Assume that distances are 6 (10, 7) h3 = 14

rectilinear. If multiple optima exist, find all (12, 5)

optimal solutions. h2 = 16

(5, 4) 6 8 10 12 14
Mini-Max Location Formulae
c1 = min {ai + bi - hi}
c2 = max {ai + bi + hi}
c3 = min {-ai + bi - hi}
c4 = max {-ai + bi + hi}
c5 = max (c2 - c1, c4 - c3}
Set of optimal solutions: line segment defined by the following
end points:

(x1*, y1*) = 1/2 (c1 - c3, c1 + c3 + c5)

(x2*, y2*) = 1/2 (c2 - c4, c2 + c4 - c5)

Solution
m=4 P1 = (6, 11) h1 = 10 P2 = (12, 5) h2 = 16
P3 = (14, 7)h3 = 14 P4 = (10, 16) h4 = 11
c1 = min {ai + bi - hi} = min {6+11-10, 12+5-16, 14+7-14, 10+16-11} =
c2 = max {ai + bi + hi} = max {6+11+10, 12+5+16, 14+7+14, 10+16+11} =
c3 = min {-ai + bi - hi} = min {-6+11-10, -12+5-16, -14+7-14, -10+16-11} =
c4 = max {-ai + bi + hi} = max {-6+11+10, -12+5+16, -14+7+14, -10+16+11} =
c5 = max (c2 - c1, c4 - c3}= max { - , - }=
Optimal objective value:

Set of optimal solutions: line segment defined by the following end points:

(x1*, y1*) = (c1 - c3, c1 + c3 + c5) = ( - , + + )=( , )

(x2*, y2*) = (c2 - c4, c2 + c4 - c5) = ( - , + - )=( , )

Ardalan Heuristic
Need a matrix of distances or costs from each
customer location to every other location
Demand at each location
Weight – give higher weight to more important
customers – their pain of traveling a longer
distance is worth more.
Only consider locating where customers are
Identify the one best place to locate at, then the
second one to add, then the third, etc.
Ardalan Heuristic
Minimize weighted distance traveled
To
From AB C D Dem. Weight
A 0 11 8 12 10 1.1
B 11 0 10 7 8 1.4
C 8 10 0 9 20 0.7
D 9.5 7 9 0 12 1.0
Ardalan Method
Expected demand at each location.
Weight represents importance of serving location
(bigger = more important)
Step 1: Multiply distances * weights * demand
 A to B: 11 * 1.1 * 10 = 121
Ardalan Method
Step 2. Add up values in columns
From A B C D
A 0 121 88 132
B 123.2 0 112 78.4
C 112 140 0 126
D 114 84 108 0
349.2 345 308 336.4
Ardalan Method
Choose smallest value as first site.
From A B C D
A 0 121 88 132
B 123.2 0 112 78.4
C 112 140 0 126
D 114 84 108 0
349.2 345 308 336.4
Ardalan Method
3. If larger, set each cost equal to cost in same row in
the chosen column
From A B C D
A 0 88 88 88
B 112 0 112 78.4
C 0 0 0 0
D 108 84 108 0
220 172308 166.4
Ardalan Method
Get rid of previously chosen column.
Sum, choose smallest sum.
From A B D
A 0 88 88
B 112 0 78.4
C 0 0 0
D 108 84 0
220 172 166.4
Ardalan Method
Repeat 3 & 4 until enough sites chosen.
From A B D
A 0 88 88
B 78.4 0 78.4
C 0 0 0
D 0 0 0
78.4 88 166.4
Ardalan Method
Repeat 3 & 4 until enough sites chosen.
From A B
A 0 88
B 78.4 0
C 0 0
D 0 0
78.4 88
Ardalan Summary
What we decided is that if we only want to build one
location, it should be in C.
If we want to build two, they should be in C and D. If
we add a third one, it should be in A.
Ardalan Summary
Assumes that we have to locate in the same city as one of
our customers, which is not always the case.
However, it can be used to find more than one location.
Center of Gravity does not try to locate in the same city as
one of the customers, but can only set one site.
If we choose the same sites as customers A and X, we
obviously don’t really have to put the warehouses in those
exact cities.
Plant layout
PLANT LAYOUT
According to Mallick and Gaudreau-
“A floor plant for determining and arranging the
desired machinery and equipment of plant, in one
best place, to permit the quickest flow of materials at
the lowest cost and with the least amount of handling
in processing the product from the receipt of raw
materials to the shipment of finished products.”
Objectives of Plant Layout
To facilitate manufacturing process
To minimize material handling
To maintain high turnover of semi-finished goods
Effective utilization of space
To provide employees comfort and job satisfaction
To provide effective utilization of labor
Principles of Plant Layout
Principle of overall integration
Principle of minimum distance
Principle of flow
Principle of cubic space
Principle of satisfaction and safety
Principle of flexibility
Factors affecting Plant Layout
 The final solution for a Plant Layout has to take into account a
balance among the characteristics and considerations of all factors
affecting plant layout, in order to get the maximum advantages.
 The factors affecting plant layout can be grouped into 8 categories:
 Materials
 Machinery
 Labor
 Material Handling
 Waiting Time
 Auxiliary Services
 The building
 Future Changes
Factors affecting Plant Layout
The factors affecting plant layout can be grouped into 8
categories:
 Materials
 The layout of the productive equipment will depend on the
characteristics of the product to be managed at the facility, as well
as the different parts and materials to work on.
 Main factors to be considered: size, shape, volume, weight, and the

physical-chemical characteristics, since they influence the

manufacturing methods and storage and material handling
processes.
 The sequence and order of the operations will affect plant layout as

well, taking into account the variety and quantity to produce.

Factors affecting Plant Layout
The factors affecting plant layout can be grouped into 8
categories:
 Machinery
 Having information about the processes, machinery, tools and
necessary equipment, as well as their use and requirements is
essential to design a correct layout.
 The methods and time studies to improve the processes are closely

linked to the plant layout.

 Regarding machinery, we have to consider the type, total available

for each type, as well as type and quantity of tools and equipment.
 It’s essential as well to know about space required, shape, height,

weight, quantity and type of workers required, risks for the

personnel, requirements of auxiliary services, etc.
Factors affecting Plant Layout
The factors affecting plant layout can be grouped into 8
categories:
 Labor
 Labor has to be organized in the production process (direct labor,
supervision and auxiliary services).
 Environment considerations: employees’ safety, light conditions,
ventilation, temperature, noise, etc.
 Process considerations: personnel qualifications, flexibility,
number of workers required at a given time as well as the type of
work to be performed by them.
 Material Handling
 Material handling does not add value to the product; it’s just waste.
 Objective: Minimize material handling as well as combining with
other operations when possible, eliminating unnecessary and
costly movements.
Factors affecting Plant Layout
The factors affecting plant layout can be grouped into 8
categories:
 Waiting time - Stock
 Objective: Continuous Material Flow through the facility, avoiding
the cost of waiting time and demurrages that happen when the
flow stops.
 On the other hand, the material waiting to flow through the

facility not always represents a cost to avoid. As stock sometimes

provides safety to protect production, improving customer service,
allowing more economic batches, etc.
 It’s necessary then to consider space for the required stock at the facility
when designing the layout.
 Resting time to cool down or heating up…
Factors affecting Plant Layout
The factors affecting plant layout can be grouped into 8
categories:
 Auxiliary Services
 Support the main production activities at the plant:
 Related to labor: Accessibility paths, fire protection installations,
supervision, safety, etc.
 Related to material: quality control.

 Related to machinery: maintenance and electrical and water lines.

 The auxiliary services represent around 30% of the space at a

facility.
 The space dedicated to auxiliary services is usually considered as

waste.
 It’s important to have efficient services to insure that their indirect costs
have been minimized.
Factors affecting Plant Layout
The factors affecting plant layout can be grouped into 8
categories:
 The building
 If it has been already selected, its characteristics will be a constraint at
the moment of designing the layout, which is different if the building
has to be built.
 Future changes
 One of the main objectives of plant layout is flexibility.
 It’s important to forecast the future changes to avoid having an

inefficient plant layout in a short term.

 Flexibility can be reached keeping the original layout as free as

possible regarding fixed characteristics, allowing the adjustment to

emergencies and variations of the normal process activities.
 Possible future extensions of the facility must be taken into account,

as well as the feasibility of production during re-layout.

Types of Plant Layout
The production process normally determines the type
of plant layout to be applied to the facility:
 Fixed position or Project plant layout
 Product stays and resources move to it.
 Product oriented plant layout
 Machinery and Materials are placed following the product path.

 Process oriented plant layout (Functional Layout).

 Machinery is placed according to what they do and materials go

to them.
 Cell Layout
 Hybrid Layout that tries to take advantage of different layouts

types.
Fixed position or Project plant
layout
Fixed position or Project plant layout
In Fixed product layout, the products generally circulate
within the production facilities (machines, workers, etc.)
 In this particular type of layout, the product does not
move, it is the different resources that are moved to
perform the operations on the product.
 This type of layout is commonly found in industries that
manufacture large size products, such as ships or aircrafts.
Product oriented plant layout
Types of Plant Layout
Product oriented plant layout
 This type of plant layout is useful when the production process
is organized in a continuous or repetitive way.
 Continuous flow: The correct operations flow is reached through
the layout design and the equipment and machinery specifications.
 Repetitive flow (assembly line): The correct operations flow will be

based in a line balancing exercise, in order to avoid problems

generated by bottle necks.
 The plant layout will be based in allocating a machine as close
as possible to the next one in line, in the correct sequence to
manufacture the product.
Types of Plant Layout
Product oriented plant layout
 Advantages:
 Reduced material handling activities.
 Work In Process almost eliminated.

 Minimum manufacturing time.

 Simplification of the production planning and control systems.

 Tasks simplification.

 Disadvantages:
 No flexibility in the production process.
 Low flexibility in the manufacturing times.

 High capital investment.

 Every workstation is critical to the process.- The lack of personnel or shut

down of a machine stops the whole process.

 Monotonous work.
Process oriented plant layout
(Functional Layout)
Types of Plant Layout
Process oriented plant layout (Functional Layout)
 This type of plant layout is useful when the production process
is organized in batches.
 Personnel and equipment to perform the same function are
allocated in the same area.
 The different items have to move from one area to another one,
according to the sequence of operations previously established.
 The variety of products to produce will lead to a diversity of
flows through the facility.
 The variations in the production volumes from one period to
the next one (short periods of time) may lead to modifications
in the manufactured quantities as well as the types of products
to be produced.
Types of Plant Layout
Work cells
Definition:
 Group of equipment and workers that perform a sequence of
operations over multiple units of an item or family of items.
Looks for the advantages of product and process layouts:
 Product oriented layout: Efficiency

 Process oriented layout: Flexibility

Group Technology
 Grouping outputs with the same characteristics to families, and
assigning groups of machines and workers for the production of
each family.
 Cellular Layout

Process (Functional) Layout Group (Cellular) Layout

A cluster
or cell
T T T CG CG T T T
M
T T T SG SG M M T

D D M D
M M D D D
SG CG CG D

M M D D D SG

Resources to produce similar

Similar resources placed together
products placed together
Plant Layout for a Service Business
Most of the concepts and techniques explained here can
be applied to any plant layout, including services.
 Examples: Line Balancing for Restaurant self-services; Process
oriented layout for Hospitals.
Service Businesses have a more direct customer focus:
 Sometimes, the customer is required at the facility for the
company to be able to perform the service.
 Frequently, the layout is focused on the customer satisfaction
than on the operation itself.
 Some of the objectives include comfortability during the
performance of the service, as well as making attractive those
areas in direct contact with the customer.
Plant Layout for a Service Business
Service Businesses have a more direct customer focus:
 The customer, with his/her presence, creates the work flow.
 The workload forecast and the activities planning is not as accurate
as it is in a manufacturing environment.
 Queues:
 Seasonal and heterogeneous demand: execution time can be variable.
 Services are intangible: adjustment between demand and production

can not be done through inventory management.

 Queues are formed by people: higher implications for the layout.
Plant Layout for a Service Business
Plant layout for an office:
 The material that flows among departments and workstations is
basically information. This can be done through:
 Individual conversations face to face.
 Individual conversations through telephone or computer.
 Mail and other physical documents.

 Electronic mail.

 Meetings and discussion groups.

 Interphones.

 The layout solution is dictated by workers and physical

documentation movements.
Plant Layout for a Service Business
Plant layout for a commerce:
 Objective: Maximize the net benefit per m2 of shelves.
 If sales are directly related to the exposition of products to the
customer, the objective will consist of exposing as many products
as possible to the customers in the available space.
 This has to take into account to leave enough space for the movement
among shelves, not making the layout uncomfortable for the customer.
Aspects:
 Allocation of daily consumption products at the periphery.- Allocation
of impulsive purchase and high profit margin products in prominent
places.
 Eliminate aisles that allow the customers to go from one row to other

without going through them completely.

Plant Layout for a Service Business
Plant layout for a commerce:
Aspects:
 Global organization of the available space:
 Allocation of attraction products on both sides of a row, and dispersion
of them to increase the exposition of adjacent products.
 Use the end of a row as a place for exposition.

 Creation of the business image through a careful selection of the first

section where the customers are getting into the facility.

 Allocation of products in the exposition areas:
 This aspect remains within the commercial function. It is called
merchandising.
 Three Retail Layout Patterns
 Grid

 Rectangular with parallel

aisles; formal; controls
traffic flow; uses selling
space efficiently.
 Free-Form
 Free-flowing; informal; Cafetería
creates "friendly"
environment; flexible.
 Boutique
 Divides store into a series
of individual shopping
areas, each with its own
theme; unique shopping
environment.

Cafetería
Plant Layout for a Warehouse
 Objective: Optimal relationship between space and material handling costs.
 Aspects to be considered: cubic space utilization, storing equipment and methods,
material protection, allocation of different parts, etc.
 A warehouse layout is more complicated when:
 The different customer orders take into account a high number of references.
 There are frequent orders of low numberZones
of units for theZones
same product.
Control
station Shipping


Click to add title
In this cases, the material handling costs for each roundtrip move would be excessively high. doors
Solutions for this problem: Aggregation of units for several orders, or establishment of optimal
routes for each order.

Tractor
trailer

Tractor
trailer
Feeder Feeder
lines lines Overflow
Flexible Manufacturing
Systems (FMS)
What is an FMS?
A flexible manufacturing system (FMS) is a
manufacturing system in which there is some amount of
flexibility that allows the system to react in the case of
changes, whether predicted or unpredicted.
Two categories of flexibility
 Machine flexibility, covers the system's ability to be changed to
produce new product types, and ability to change the order of
operations executed on a part.
 Routing flexibility, which consists of the ability to use multiple
machines to perform the same operation on a part, as well as the
system's ability to absorb large-scale changes, such as in volume,
capacity, or capability.
Definition
A Flexible Manufacturing System (FMS) is a
production system consisting of a set of identical and/or
complementary numerically controlled machine which
are connected through an automated transportation
system.
each process in FMS is controlled by a dedicated
computer (FMS cell computer).
Equipment of FMS
Primary equipment
work centers
• Universal machining centers (prismatic FMSs)
• Turning centers (rotational FMSs)
• Grinding machines
• Nibbling machines
Process centers
• Wash machines
• Coordinate measuring machines
• Robotic work stations
• Manual workstations
Equipment of FMS
Secondary equipment
Support stations
• Pallet/fixture load/unload stations
• Tool commissioning/setting area
Support equipment
• Robots
• Pallet/fixture/stillage stores
• Pallet buffer stations
• Tools stores
• Raw material stores
• Transport system(AGVs,RGVs,robots)
• Transport units(pallets/stillages)
Types of FMS

 Sequential FMS
 Random FMS
 Dedicated FMS
 Engineered FMS
 Modular FMS   
Illustration example of a FMS
Application of FMS
Metal-cutting machining
Metal forming
Assembly
Joining-welding (arc , spot), glueing
Surface treatment
Inspection
Testing
FMS Layout Configurations
The types of commonly found FMS layout
configurations:
1. Progressive (In-line )layout
2. Loop layout
3. Ladder layout
4. Open field layout
5. Robot-centered cell
 Nuts and Bolts of FMS

FMS Layouts

Progressive (Inline)Layout:
 Best for producing a variety of parts

Closed Loop Layout:

 Parts can skip stations for flexibility
 Used for large part sizes
 Best for long process times
FMS Layouts Continued

• Ladder Layout:
― Parts can be sent to any machine in any sequence
― Parts not limited to particular part families

• Open Field Layout:

― Most complex FMS layout
― Includes several support stations
In-line layout
Loop Layout
Ladder Layout