Timeline
The line along the bottom of a value stream map that adds up the time a product spends waiting and being worked on. It steps up under each inventory, for the waiting time, and down under each process, for the processing time.
How to read it
The UW-Stout study describes the timeline as showing value-added times (cycle times) and non-value-added (wait) times, and as the line used to work out the lead time and the total cycle time. University of Minho researchers, writing in Production Engineering Archives in 2026, cite Rother and Shook’s Learning to See for its simplest form: the inventory lead time on one level and the value-added or processing time on the other. The Lean Enterprise Institute defines lead time as the time one piece takes to move all the way through a process or a value stream.
Also searched as: lead time ladder, timeline symbol, value stream map timeline, vsm timeline.
Variations
The EPA’s toolkit adds a materials line along the bottom of the map, drawn in the same way as the timeline, showing the materials each process uses against the materials that end up in the product.
Look-alikes
The zigzag arrow on the same maps is not a timeline: the UW-Stout study describes it as electronic information flow.
Read next
- Next in Value stream mapping symbolsInventory triangleMaterial waiting between two processes. The inventory icon is a triangle with the letter I inside, with the quantity or the days of stock written beneath it.
- The same shape in Smoke and CO alarm soundsLow-frequency 520 Hz alarm (sleeping rooms)A fire alarm in a sleeping room that sounds a low buzz in place of a high-pitched beep. It is the three-beep fire alarm rhythm at 520 Hz, which NFPA 72 requires of alarms provided to wake people in sleeping areas.
More value stream mapping symbols
The same shape elsewhere
Browse symbols drawn with letters and numbers or lines.
Sources
- Value Stream Mapping at XYZ Company, Madhubala Rauniyar, MS research paper, May 2007, Appendix A: Value Stream Process symbols, University of Wisconsin-Stout (MINDS@UW), Appendix A, Timeline
- Value Stream Mapping: some Pragmatic Aspects, Rui Manuel Sousa, José Dinis-Carvalho and Peter Hines, Production Engineering Archives 32(1), 2026, 112–122 (CC BY), University of Minho; Production Engineering Archives, Section 4.1
- Value-Stream Mapping, Lexicon term, Lean Enterprise Institute, Zones of a value-stream map
- Lean and Environment Toolkit, Version 1.0, Chapter 3 and Appendix A (Common Icons Used in Value Stream Maps), US Environmental Protection Agency, Chapter 3, Materials Line
Researched, edited and approved by Rory Hansen before publishing. Last reviewed October 9, 2026. How we research
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