Lean Blog Audio: Practical Lean Thinking, Psychological Safety, and Continuous Improvement Five NUMMI Tour Lessons That Still Define Lean Thinking
In this episode, Mark reflects on a visit he made twenty years ago to the NUMMI plant in Fremont, California — the Toyota-GM joint venture that became legendary in Lean circles. What stayed with him wasn’t flashy tools or so-called Lean perfection, but a series of small, human moments that revealed how Lean actually works as a management system.
Through six short stories — a broken escalator, aluminum foil, an explanatory safety sign, a pull-based gift shop, imperfect 5S, and visible audit boards — Mark explores the deeper principles behind Lean thinking: asking “why” before spending money, respecting people enough to explain decisions, encouraging small frontline ideas, and reinforcing standards through daily leadership behavior. Long before the term was popular, NUMMI demonstrated psychological safety in action.
The episode also contrasts NUMMI’s management system with what came after, when the same building became Tesla’s first factory — underscoring a central lesson: buildings and technology don’t create quality. Culture does. These NUMMI lessons remain just as relevant today for leaders trying to build systems that support learning, accountability, and continuous improvement.
Explore the original NUMMI Tour Tales:
- NUMMI Tour Tale #1: Why Fix the Escalator?
- NUMMI Tour Tale #2: The Power of Reynolds Wrap
- NUMMI Tour Tale #3: The Power of Why
- NUMMI Tour Tale #4: The Pull Gift Shop
- NUMMI Tour Tale #5: Nobody Is Perfect
- NUMMI Tour Tales #6: “You Get What You Inspect”