Directorate of distance education

The Role of Computers in Job Shop Layout
Solving the job shop layout problem can be time-consuming and 
tedious. Several computer procedures exist for assisting with the layout. 
Computerized Relative Allocation of Facilities Technique (CRAFT) 
was developed by Buffa and Armour. It works much like the procedure 
described in the previous section. The user supplies an initial layout, 
an activity level matrix, and cost information. If certain departments 
must be located together to share a key resource, this can be specified. If 
departments cannot be adjacent, this can also be specified.
These computer procedures can calculate many alternatives very 
quickly. CRAFT reduces the cost by switching all department pairs and 
calculating values for (A)(C)(D) for each alternative. The lowest-cost 
alternative is selected for further analysis, and the switching of pairs 
continues.

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Notes
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Although the stopping rules for computer-based procedures are 
still somewhat arbitrary, they are easier to implement then those for a 
manual procedure. The brute power and speed of the computer allow it to 
investigate quickly far more alternatives than can be reasonably done by 
hand. The following approaches can be considered:
1. Specify a certain amount of computer time, and use the best solution 
found.
2. Allow the model to perform the switching of pairs only a certain 
number of times.
3. Specify an increment of improvement to be achieved with each 
evaluation. If this is not achieved, the procedure will end. For 
example, one could specify that at least a 2 percent reduction from 
the last solution must be achieved or the search ends.
4. Combine some of these rules. For example, the procedure can 
stop after a certain amount of time or after a specified number of 
switches, whichever is lower.
Other computer-based procedures, such as computerized Facil-
ity Design (COCAD), Plant Layout Analysis and Evaluation Technique 
(PLANET), Computerized Relationship Layout Planning (CORELAP), 
and Automated Layout Design Programs (ALDEP), are also available. 
These procedures attempt to maximize nearness ratings. However, solu-
tions Generated by these computer models are not guaranteed to be op-
timal.