Which step is holding your team up?
Enter your workflow’s steps, what each finishes per day, and real arrivals from your tracker. Queueglass replays them, names the step that limits flow and reruns the line with one more unit of capacity at each step.
Example: purchase-order lines in the CAPEX & SOCS spend area of the BPI Challenge 2019 log, 2018, per day
Goods receipt limits flow.
It held work back on 20 of 367 days replayed.
The backlog peaks at 78 items on 31 Oct 2018 and clears by 3 Nov 2018, 3 days later.
With 47 a day at Goods receipt instead of 46, it would not clear any sooner; waiting would drop from 389 item-days to 363 item-days.
One more per day at each step
Each row is a full rerun of the same arrivals with that step’s capacity raised by one.
| Capacity change | Peak backlog | Backlog cleared | Item-days waiting |
|---|---|---|---|
| As entered | 78 | 3 Nov 2018 | 389 |
| Goods receipt 46 → 47 | 77 | 3 Nov 2018 | 363 |
| Invoice receipt 49 → 50 | 78 | 3 Nov 2018 | 389 |
| Invoice clearing 142 → 143 | 78 | 3 Nov 2018 | 389 |
Item-days waiting adds up, over the whole replay, every item that was ready to move and couldn’t.
Your line
Steps in order, what each finishes per day, and the work that arrived. It all stays in this browser.
one waiting item share of this day’s capacity used
Goods receipt
Bottleneck78waiting46 of 46 movedInvoice receipt
Moving46waiting23 of 49 movedInvoice clearing
Moving23waiting21 of 142 moved
Replay
367 days, including the days after the last arrival while the line drains. Drag across the lanes or use the slider.
Show every period as a table
At 31 Oct 2018items
- Arrived so far
- 5711
- Finished so far
- 5564
- In the line now
- 147
- Held back this day
- 78
- Average days to finish
- 3.02
How the replay works
Each day, that day’s arrivals join the first step. Steps are served from the last back to the first, oldest work first, each up to its capacity. An item moves at most one step per day, so a line of 3 steps takes at least 3 days end to end. With a WIP limit, a step stops passing work on while the next step already has that many waiting.
The backlog is the work that was ready to move and couldn’t. The bottleneck in a day is the step that left the most of it, and the step that limits flow is the one that was the bottleneck most often. The +1 rows are not estimates: each is the whole replay run again.
Capacity should be measured, not hoped for: count what each step actually finished on a busy day. The model assumes every item passes every step and that capacity is the same every day, weekends included.
Space plays or pauses. ← → step one day.
Where the example comes from
The arrivals are the purchase-order lines created each day of 2018 in the CAPEX & SOCS spend area of the BPI Challenge 2019 event log from a coatings and paints company: B. F. van Dongen, 4TU.ResearchData, doi:10.4121/uuid:d06aff4b-79f0-45e6-8ec8-e19730c248f1, licensed CC BY 4.0.
The three steps are the log’s goods receipt, invoice receipt and invoice clearing. Each capacity is that activity’s 90th-percentile daily count on the days it ran. Queueglass changed the data by counting events per day; the derivation script and the derived CSV are in the repository.
Your data
Your steps and arrivals are replayed in this tab. The share link keeps them after the #, which browsers do not send to any server, so the link itself is the only copy.