A recent trend has been the development of computer programme to assist the layout planner in generating alternative layout designs. Computerised layout planning can improve the search of the layout design process by quickly generating a large number of alternative layouts.
Computer programmers are generally either construction programmers or improvement programmers:
| 1 | Construction programmers (Successive selection and placement of activities) | Construction programmers Relationship Layout Planning)ALDEP(Automated Layout Design Programme) |
| 2 | Improvements programmers | CRAFT (Computerized Relative Allocation of Facilities Techniques) (A complete existing layout is required initially and locations of departments are inter-changed to improve the layout design) |
Both ALDEP and CORELAP are concerned with the construction of a layout based on the closeness ratings given by the REL chart.
CRAFT is concerned. With the minimization of a linear function of the movement between departments Typically CRAFT employs an improvement procedure to obtain a layout design based on the objective of minimizing material handling costs.
CORELAP
It begins by calculating which of the activities in the layout is the busiest or most related. The sums of each activity’s closeness relationships with all other activities are compared and the activity with the highest total closeness relationship (TCR) count is selected and located first in the layout matrix. This activity is named Winner. Next, an activity which must be close to the winner is selected and placed as adjacent as possible to winner: This activity is denoted as A (closeness absolutely necessary) and is named Victor. A search of winner’s remaining relationships for more A-related victors is then made. These are placed, again, as close to each other as possible. If no more A’s can be found, the victors become potential winners and their relationships are searched for A’s. If an A is found, the victor becomes the new winner, and the procedure is repeated. When no A’s are found, the same procedure is repeated for E’s (closeness Especially important), I’s (closeness important), and 0’s (Ordinary closeness o.k.) until all activities have been placed in the layout. CORELAP also puts a value on the U (closeness Unimportant) and X (closeness not desirable) relationship.
ALDEP
It uses a preference table of relationship values in matrix form to calculate the scores of a series of randomly generated layouts. If for example, activities 11 and 19 are adjacent, the value of the relationship between the two would be added to that layout’s score. A modified random selection technique is used to generate alternate layouts. The first activity is selected and located at random. Next, the relationship data are searched to find an activity with a high relationship to the first activity. This activity is placed adjacent to the first. If none is found, a second activity is selected at random and placed next to the first. This procedure is continued until all activities are placed. The entire procedure is repeated to generate another layout. The analyst specifies the number of layouts wanted which must satisfy a minimum score.
CRAFT
It is the only one which uses flow of materials data as the sole basis for development of closeness relationships. Material flow, in terms of some unit of measurement (pounds per day, in terms of skid-loads per week), between each pair of activity areas, forms the matrix to the programme.
A second set of input data allows the user to enter cost of moving in terms of cost per unit moved per unit distance. In many cases this cost input is unavailable or inadequate, in which case it can be neutralized by entering 1.0 for all costs in the matrix.
Space requirements are the third set of input data for CRAFT. These take the form of an initial or an existing layout. For new area layouts, best guess or even completely random layouts can be used. In any case, activity identification numbers, in a quantity approximate to their space requirements, are entered in an overall area of continuation. The location of any activity can be fixed in the overall area through control cards CRAFT limits the number of activities involved in the layout to 40.
