Activity relationship chart

An activity relationship chart (ARC) is a tabular means of displaying the closeness rating among all pairs of activities or departments.^[1] In an ARC there are six closeness ratings which may be assigned to each pair of departments, as well as nine reasons for those ratings (each is assigned by a reason code).

Rating symbols

1. A: Absolutely necessary
2. E: Especially important
3. I: Important and core
4. O: Ordinary
5. U: Unimportant
6. X: Prohibited or Undesirable ^[2]

Reason codes

1. Same table
2. Flow of material
3. Service
4. Convenience
5. Inventory control
6. Communication
7. Same personnel
8. Cleanliness
9. Flow of parts^[2]

A rule of thumb is used to restrict the choice of rating letters:

• Very few A and X relationships (no more than five percent) should be assigned
• No more than 10 percent should be E
• No more than 15 percent should be I
• No more than 20 percent should be O
• About 50 percent of the relationships should be U

Developing an ARC

1. List all the departments within the facility, and draw a rectangle around each one.
2. Draw a rhombus between each department, until you fully construct the rhombus as a tree.
3. Divide each rhombus into two halves; the upper half will contain the rating letter, while the lower half will contain the rating-reason code.

See also

• distance matrix
• correlation matrix

References

1. Groover, M. P. (2007). Work Systems: The Methods, Measurement & Management of Work, Prentice Hall, ISBN 978-0-13-140650-6
2. Tompkins, J. A., White, J. A., Bozer, Y. A. (2010). Facilities Planning, Wiley, ISBN 978-0-470-44404-7