Lear · Body 2 · 31XX-2 · measured 25 August 2026

Body 2 Work Content

What the line actually does, measured from the cameras already installed — with no reference to the standard work sheet.

Work content varies 2.6× across the twelve stations measured — from 2.1 to 5.5 person-minutes per board. Two stations are running out of time; two have spare capacity; and the imbalance does not travel down the line, which means it can be fixed one station at a time.

Work content per board

person-minutes of hands-on work · measured, not planned

B2C14

5.53

B2C17

4.25

B2C15

4.23

B2C10

4.17

B2C18

4.15

B2C8

4.12

B2C13

3.76

B2C6

3.61

B2C7

3.23

B2C5

3.20

B2C11

2.78

B2C12

2.10

02.0 4.0 5.97 — available now 7.03 at takt

■ work does not fit — operators chase boards downstream ■ spare capacity ─ ─ person-minutes available per board

How to read the two dashed lines. At the line's current speed — a board every 179 seconds — a two-person station has 5.97 person-minutes to finish each board. If the line ran at takt instead (211 s) it would have 7.03. Every bar is below both lines, so on average the work fits. The problem is not the average, it is the spread.

Where the work does not fit

operators who left their station following a board out

The line tells you this itself. When an operator cannot finish inside the pitch, they follow the board downstream rather than let it go incomplete. We counted how often that happens at each station — no standard times, no plan, just what the operators did.

Station	Work content p-min/board	Chase index	Left downstream vs upstream	Reading
B2C7	3.23	17.3	67 : 3	work does not fit
B2C10	4.17	14.8	90 : 5	work does not fit
B2C5	3.20	14.2	97 : 26	work does not fit
B2C6	3.61	12.3	56 : 11	work does not fit
B2C13	3.76	12.1	111 : 46	work does not fit
B2C18	4.15	12.1	73 : 85	mixed
B2C11	2.78	10.9	60 : 65	mixed
B2C17	4.25	9.2	132 : 82	busy, mostly coping
B2C14	5.53	6.0	38 : 47	highest content, coping
B2C15	4.23	3.9	54 : 36	coping
B2C12	2.10	3.9	23 : 54	spare — works ahead
B2C8	4.12	2.2	12 : 32	spare — works ahead

Chase index is the share of a station's own operator-appearances that end with the operator leaving downstream. It is a comparison between stations, not a count of boards — see note 3. Work content and chase index are only weakly related (see note 4), which is the point: B2C14 carries the most work on the line and copes with it, while B2C7 carries below-average work and cannot. You need both numbers to know what to do.

Two moves to make first

adjacent stations · every measurement agrees

Move work from B2C7 into B2C8

the strongest signal on the line

B2C7 has the highest chase index on the line at 17.3 — its operators followed the board out 67 times against 3 the other way. B2C8, immediately downstream, has the lowest at 2.2 and habitually works ahead. They are adjacent, so the transfer is a work-element move rather than a re-layout.

B2C7 · 3.23 p-min

chase 17.3 — cannot finish

→

B2C8 · 4.12 p-min

chase 2.2 — absorbs today

Move work from B2C13 into B2C12

largest work-content gap between neighbours

B2C12 carries the least work on the line at 2.10 person-minutes per board — 35% of what is available to it — and spends its spare time working ahead. B2C13 next door carries 3.76 and chases boards at 12.1. Levelling these two alone would remove the widest gap between any adjacent pair we measured.

B2C13 · 3.76 p-min

chase 12.1

→

B2C12 · 2.10 p-min

chase 3.9 — 35% loaded

No cascading-down effect

an overload at one station does not push work onto the next

A reasonable worry with this kind of measurement is that one overloaded station pushes work onto the next, which pushes it onto the next. If that were happening you could not act on any single station without tracing the whole line first.

It is not happening here. Pressure builds over two or three stations and is then absorbed by a station with spare capacity. B2C8 and B2C12 both sit immediately after a run of chasing and act as relief valves.

We also checked whether a busy five minutes at one station predicts a busy five minutes at the next. It does not — see note 5. Each station's number is its own, which is why the two moves above can be made independently and in either order.

B2C5 ████████████ chase 14.2 B2C6 ███████ chase 12.3 absorbed B2C7 ███████████ chase 17.3 builds B2C8 ██ chase 2.2 absorbed · · · B2C9 — no camera · · · B2C10 ███████████ chase 14.8 B2C11 ████████ chase 10.9 absorbed B2C12 ███ chase 3.9 absorbed B2C13 ██████████████ chase 12.1 builds B2C14 ██████████ chase 6.0 absorbed B2C15 ███████ chase 3.9 absorbed · · · B2C16 — no camera · · · B2C17 ████████████████ chase 9.2 B2C18 █████████ chase 12.1

What this needs to become routine

from a one-off study to a shift-by-shift measure

The other ten stations. Twelve of twenty-two were measurable. Four cameras showed as offline on Lear's own layout; six more were not in the export. The gaps at B2C9 and B2C16 also break the line into segments, which limits how far any flow conclusion can travel.
More than one product mix. This is two hours of one evening. Work content per station moves with the harness variant, and a balance conclusion drawn on one mix can invert on another.
Two cameras need repositioning before their numbers are used. B2C11 views a walkway rather than its work area. B2C12 — the lightest station on the line — has not been confirmed either way, and its result is significant enough to be worth verifying rather than assuming.
An unexplained shift. The line ran roughly 40% leaner in the second hour than the first, across most stations. Worth knowing what changed at 2 PM local before that is read as a pattern.

Notes on method

What was measured. Operators were detected by a pose model in a region drawn on each station's work area. An operator counts as working when their wrists are low relative to their own shoulders and hips — reaching into the board. Validated against 36 frames scored by hand across 9 stations: mean absolute error 0.28 operators for engagement, 0.39 for presence, within one operator on 97% of frames.
Work content per board = engaged person-minutes per hour ÷ 20.1 boards per hour. Pitch of 179 s was measured three independent ways — board QR tracking, and occupancy rhythm at both 1-second and 15-second sampling — agreeing within 4 seconds. Takt of 211 s was supplied by Lear.
Chase index is the percentage of a station's own operator-appearances that end at the downstream edge. It is deliberately not expressed per board: the tracker fragments a single person into several tracks when they are occluded, which inflates absolute counts by an unknown factor. Dividing by appearances — inflated the same way — largely cancels this. Ranking by raw hourly rate instead gives a materially different order (rank correlation 0.62), and we use the fragmentation-robust version.
Work content and chase index correlate at r = +0.30 across the twelve stations — weakly. They measure different things: how much work is done, versus how much did not fit in the pitch.
Cascade test. Across nine adjacent station pairs, correlation between downstream-exit counts in the same 5-minute block was +0.14, and +0.02 one block later. Only one pair of nine exceeded 0.4. Station transit is 120 s against a 5-minute block, so a cascade would appear in the same block; a faster whiplash within a single block would not be resolved by this test.
Direction is behaviour, not camera geometry. Correlation between where operators typically stand within a region and which edge they exit by is −0.01. Stations with high chase indices also drift downstream while working (+0.04 to +0.10 of region width); B2C12 drifts upstream.
Cameras do not overlap, so no operator is counted twice. Confirmed three ways: feature matching between adjacent views, visual inspection, and board-ID coincidence — no board appeared in two cameras at the same instant across 14,000 tracked appearances.