Activity relationship chart

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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[edit]

  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[edit]

  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[edit]

  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[edit]


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