A spaghetti diagram, spaghetti plot or spaghetti chart is the drawing depicting the physical flow or route of:
- a part, raw material in a workshop or factory
- a human worker in his/her work environment
- a patient in his/her journey in a hospital
- nurses in their station
- a file or paperwork being handed over across offices
The drawing of the journey will show how intricate the route is, looking like a plate of spaghetti, hence the name.
Spaghetti chart, what for?
These charts are used to analyze the distance covered, the going back and forth to some place, the wasted time in motion and/or transportation (muda).
People are often unaware what distances they walk in a day and management is unaware of the time spent moving around the place wasting time and energy.
Spaghetti chart are useful to redesign a layout or reposition some equipment in order to reduce the unnecessary walking time and fatigue, which is only waste.
Sometimes it is the order of steps in a process that can be changed for the sake of efficiency.
A spaghetti diagram is a welcome sidekick to Value Stream Mapping, as the later maps the conceptual route through a process while the spaghetti chart shows the actual (or future) physical one.
How to draw a spaghetti chart?
Spaghetti charts depicting the actual situation should be based on real observation. On a prepared sheet with outlines of the facility, machines, equipment, etc. the observer traces the lines as the observed object/person moves from one spot to the next.
Tips and tricks
- The drawing should be more or less on scale, so that it is easier to estimate the total distance covered.
- If scale is unknown, count the steps when walking and estimate an average stride length. This will help estimate all the distances and the accumulated distance.
- When the trail is going and coming forth, draw each line separately in order to count the frequency per time unit (e.g. per quarter, per hour, etc.). it will also help to estimate the total distance by multiplying the segment length with frequency.
- Try to depict the route faithfully. Do not draw straight lines through walls as I saw once because my explanation was not specific enough!