Definition
The fixed-position stop system is Toyota’s method for stopping an assembly line when a problem is detected. Rather than halting the line immediately at the point of the problem, the line continues to move until it reaches the next fixed stop point — typically the boundary between work zones. This gives the operator or team leader a short window (the remaining time in the cycle) to resolve the issue before the line actually stops. If the problem is resolved within that window, the line continues without interruption. If it is not resolved, the line stops at the fixed position and remains stopped until the problem is addressed.
Japanese Origin
Teīchi teishi (定位置停止) combines 定位置 (teīchi, fixed position) and 停止 (teishi, stop). The concept is precisely what the name says — stopping at a predetermined, fixed location rather than at an arbitrary point. This is a practical engineering solution that balances the jidoka principle of never passing defects downstream with the production reality that not every problem requires an immediate full line stop.
History at Toyota
The fixed-position stop system was developed as Toyota applied the jidoka principle to moving assembly lines. On a stationary process, stopping immediately when a problem occurs is straightforward — the machine stops, the problem is fixed, and work resumes. But on a moving assembly line with dozens of operators working simultaneously, an immediate stop at an arbitrary point creates chaos: operators mid-cycle are interrupted, partially completed work is misaligned, and restarting becomes complicated.
Toyota’s solution was elegant. The andon system signals the problem immediately — the operator pulls the cord and the team leader is alerted. But the line does not stop at that instant. Instead, it continues to the next fixed position, giving the team leader time to arrive, assess the situation, and often resolve the problem before the line stops. This system made jidoka practical on high-speed assembly lines where an immediate stop for every minor issue would have destroyed productivity.
How It Actually Works
The sequence when an operator detects a problem:
- The operator pulls the andon cord, triggering a signal (light and/or chime) that identifies the workstation
- The line continues to move toward the next fixed stop position
- The team leader responds immediately and goes to the station
- If the team leader and operator can resolve the problem before the line reaches the fixed stop point, the andon is cleared and the line continues without interruption
- If the problem is not resolved by the fixed stop point, the line stops
- The line remains stopped until the problem is resolved and the andon is cleared
Most andon pulls do not result in a line stop. Toyota’s system is designed so that the majority of problems are resolved within the remaining cycle time. Only persistent or serious problems result in an actual stop. This is why Toyota can have hundreds of andon pulls per shift while maintaining high productivity.
The fixed positions are engineered. They correspond to the boundaries between work zones, where each operator’s cycle naturally ends. Stopping at these points means all operators have completed their current cycle, making restart clean and predictable.
Common Mistakes
Confusing fixed-position stop with not stopping. The system does not avoid stopping — it manages when and where the stop occurs. If the problem cannot be resolved within the window, the line stops absolutely. The discipline of jidoka — never pass a defect downstream — is fully maintained.
Not responding to the andon signal. The fixed-position stop system only works if the team leader responds immediately when the andon is pulled. If no one comes, the operator cannot resolve the problem alone, and the line stops every time. Fast team leader response is what makes the system effective.
Disabling the stop function. Some organizations install andon systems but disable the automatic stop, turning the andon into a call light with no consequence. This removes the jidoka discipline entirely and allows defects to pass downstream.
Applying the system to non-moving processes. Fixed-position stop is specifically designed for moving assembly lines. For stationary machining or cell-based operations, immediate stop upon abnormality detection is appropriate — there is no need for a position-based delay.