(13) computerised layout planning

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COMPUTERISED LAYOUT PLANNING

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CONSTRUCTION PROGRAMSCORELAPALDEPPLANET, LSP, LAYOPT, RMA Comp I

IMPROVEMENT PROGRAMSCRAFTRUGR (based on graph theory)

LAYOUT PLANNINGPACKAGES

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ALDEP

AutomatedLayout

DEsignProgram

Development within IBM

Seehof, J.M and W.O. Evans “Automated Layout Design Program:, The Journal of Industrial Engineering, Vol 18, No. 12, 1967, pp 690 - 695.

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ALDEP based on closeness Ratings

A 43 = 64

E 43 = 16

I 41 = 4

O 40 = 1

U 0 = 0

X -45 = -1,024

Can handle 63 departments on 3 floors

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Scoring Pattern of ALDEP

50

8

2 4

1

7 6

3

For a Cell (0) the scores of all eight neighbours areadded together (as per REL chart)

Then the cell (0) is deletedso that it is not counted again. We then proceed to the next cell till all cells are exhausted. The final cumulativescore is the Layout Score

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Inputs Requirements for ALDEP

• Length, Width and area requirements for each floor.• Scale of layout printout (max 30x50)• No. of depts. in the layout• No. of layouts to be generated• Minimum allowable score for an acceptable layout.• Minimum dept. preference (A or E)• REL chart for the depts.• Location and size of restricted area for each floor.

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Vertical Scanning Pattern for placing depts. in ALDEP

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Mechanism of ALDEP :

(a) 1st dept placed randomly.

(b) Scan the REL chart for a dept with A,E rating (min dept preference) continue this step till no such dept exists

(c) Pick up the next dept. in a random fashion and again proceed by scanning the REL chart [step (b)].

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An Example of ALDEP

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The Available Space

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B

Placement of 1st Department

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Placement of 2nd Department

B

D

D

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Placement of 3rd Department

D

B

D

A

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Placement of 4th Department

C

B

D

D

AC

C

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Final Layout

B

D

D

A

C

CC

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Features of CORELAP

• Retain the rectangular shape of each department

• The layout is built around a central department

• Placement and choice based on the total and current placement ratio

• The final layout may end up with irregular boundaries

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CRAFTComputerized

Relative

Allocation of

Facilities

Technique

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Armour, G.C. and E.S.Buffa, “A Heuristic Algorithm and Simulation Approach to Relative Location of Facilities”

Management Science, Vol 9, No. 1, 1963, pp 294-309

Buffa, E.S, G.C. Armour and T.E. Vollman “Allocating Facilities with CRAFT” Harvard Business Review, Vol 42, No.2, 1964, pp 136 - 159.

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An Example of CRAFT

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Product, Process & Schedule Data

Product Processingsequence

Dailyproduction

No of itemsin Trolley

Trolley loads/ day

1 ABCBCD 100 5 20

2 ACBD 50 5 10

3 ACBCBD 200 40 5

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Initial Layout

A D

B C

From /To

A B C D

A --- 1 2 1

B 1 --- 1 2

C 2 1 --- 1

D 1 2 1 ---

Distance Matrix for initial layout(Assuming Rectilinear Distances)

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Load MatrixFrom/To A B C D

A --- 20 15

B --- 45 15

C 45 --- 20

D ---

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Unit Cost MatrixFrom/To A B C D

A --- 1 2 1

B 1 --- 1 1

C 2 1 --- 1

D 1 1 1 ---

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Load x Unit Cost Matrix (Flow Matrix)

From/To

A B C D

A --- 20 30 50

B --- 45 15 60

C 45 --- 20 65

D --- 00

00 65 75 35

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Initial Layout (Distance Matrix)

A D

B C

From/To

A B C D

A --- 1 2 1

B 1 --- 1 2

C 2 1 --- 1

D 1 2 1 ---

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Material Handling Effort for Initial Layout

From/To

A B C D

A --- 20 30

B --- 45 15

C 45 --- 20

D ---

From/To

A B C D

A --- 1 2 1

B 1 --- 1 2

C 2 1 --- 1

D 1 2 1 ---

From/To

A B C D

A --- 20 60 80

B --- 45 30 75

C 90 --- 20 110

D --- 00

00 110 105 50 265

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P air w ise E x chang es

A BB DA C

A CC DB A

A DD AB C

B CA DC B

B DA BD C

C DA CB D

In it ia l L ayou tA DB C

265 Material Handling Effort

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Alternative 1 (Distance Matrix)

A B C D

A ---- 1 1 2

B 1 ---- 2 1

C 1 2 ---- 1

D 2 1 1 ----

B DA C

Material Handling Effort = Flow x Distance Matrix = 220

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Alternative 2 (Distance Matrix)

A B C D

A ---- 1 2 1

B 1 ---- 1 2

C 2 1 ---- 1

D 1 2 1 ----

C D B A

Material Handling Effort = Flow x Distance Matrix = 265

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Alternative 3 (Distance Matrix)

A B C D

A ---- 2 1 1

B 2 ---- 1 1

C 1 1 ---- 2

D 1 1 2 ----

D AB C

Material Handling Effort = Flow x Distance Matrix = 215

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Alternative 4 (Distance Matrix)

A B C D

A ---- 2 1 1

B 2 ---- 1 1

C 1 1 ---- 2

D 1 1 2 ----

A DC B

Material Handling Effort = Flow x Distance Matrix = 215

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Alternative 5 (Distance Matrix)

A B C D

A ---- 1 2 1

B 1 ---- 1 2

C 2 1 ---- 1

D 1 2 1 ----

A BD C

Material Handling Effort = Flow x Distance Matrix = 265

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Alternative 6 (Distance Matrix)

A B C D

A ---- 1 1 2

B 1 ---- 2 1

C 1 2 ---- 1

D 2 1 1 ----

A CB D

Material Handling Effort = Flow x Distance Matrix = 220

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P air w ise E x chang es

A BB DA C

A CC DB A

A DD AB C

B CA DC B

B DA BD C

C DA CB D

In it ia l L ayou tA DB C

265

220 265 215* 215* 265 220

MaterialHandlingEffort

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Limitations of CRAFT

• CRAFT yields a good heuristic solution that does not guarantee optimality

• This is because not all (n!) combinations are evaluated, but only (nC2) pair-wise exchange options are considered.

• In case departments are on unequal size, their centroids are exchanged which can result in irregular shapes of departments

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n nC2 = [n(n-1)]/2

n!

1 0 1 2 1 2 3 3 4 4 6 24 5 10 120 6 15 720 7 21 5040 8 28 40320 9 36 362880 10 45 3628800 11 55 39916800 12 66 479001600

8

Factorial Growth

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20! = 2.4329 X 1018 20C2 = 190

30! = 2.65252 X 1032 30C2 = 435

40! = 8.15915 X 1047 40C2 = 780

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Summary of the CRAFT procedure

• This example demonstrates one iteration of the basic CRAFT procedure

• The best layout so produced is compared with the starting layout. If it is inferior to the starting layout, the starting layout is declared optimal and the search stops

• Otherwise a new iteration with the discovered layout as the starting node is initiated

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Conclusions

• Computer packages for layout planning – Construction programs (ALDEP, CORELAP)– Improvement programs (CRAFT)

• Based on SLP procedure – Activity relationships– Material Handling Effort

• Good for generation of alternative layouts• Limitations of irregular shapes, ignoring realistic

constraints