Why Bring the Work to the Worker? A Line That Never Stops

In a workshop, a worker walks to fetch parts, returns, works, and walks again, and a substantial fraction of the day is spent moving rather than working. Bringing material past a fixed position removes that entirely, and it does something further, which is that the speed of the line rather than the worker sets the pace. Each person performs one small operation in the time available before the piece moves on, which means the task must be broken into steps of equal duration and each step becomes highly repetitive. Output per worker rises dramatically, training time falls to hours, and the individual worker exercises far less judgement.

The lineage is better documented than the popular account suggests:

• •Grain elevators used continuous belts from the late eighteenth century
• •Chicago meatpacking used overhead rails to move carcasses past workers from the 1860s
• •That arrangement was a disassembly line rather than an assembly one
• •Ford engineers visited and adapted the principle deliberately
• •The moving chassis line began at Highland Park in 1913
• •Assembly time for a car fell from over twelve hours to around ninety minutes

The effects on the people on the line were immediate and severe, and Ford's own records document them. Turnover at Highland Park reached extraordinary levels in 1913, with the company needing to hire many times its workforce over a year because people left within weeks, which was a direct response to the monotony and the pace. The response was to double the daily wage to five dollars in 1914, which was presented as generosity and was an explicit attempt to retain workers who would otherwise leave, and it worked. Later disputes across the industry concerned line speed as much as pay. The pattern of high output, high pay and low autonomy became characteristic of mass production generally.

The principle is applied far beyond factories and several of those uses move vastly more material. Mining operations run belts many kilometres long carrying ore continuously from a pit to a processing plant, which is enormously cheaper than trucking it, and the longest single installations exceed a hundred kilometres. Airports move baggage through sorting systems of extraordinary complexity, reading tags and diverting bags at high speed. Post and parcel depots do the same for packages. Agriculture uses them for grain, potatoes and sugar beet. Supermarket checkouts use a short one that brings the shopping to the operator, which is exactly the original principle at domestic scale. Moving walkways apply it to people.

The arrangement has been substantially modified since, principally by Japanese manufacturing practice from the 1950s onwards. Any worker can stop the line on finding a defect, which reverses the original principle that the line must never stop and which catches faults at the point they occur rather than at the end. Teams rotate between tasks to reduce monotony and injury. Parts arrive as needed rather than being stockpiled beside the line. Work is organised in cells for some products, with a small group building a complete assembly, which restores judgement to the worker. Automation has taken over the most repetitive operations entirely. The moving line remains, and what happens along it has changed considerably.

Moving material past fixed workers removes the walking and lets the line rather than the worker set the pace, which requires the task to be split into equal steps and makes each one repetitive. Chicago meatpacking used the principle to disassemble carcasses decades before Ford applied it to assembly in 1913. Turnover forced the five dollar day in 1914. Later practice let any worker stop the line and rotated tasks.