What can LEAN teach us? Rotaries, Roundabouts and Traffic Circles…

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by Susan Bouwer and Roland Cavanagh


LEAN Principles in the real world: 

Single Piece Flow and Autonomy

My peeve – traffic lights. Particularly several in a row. Jan and I have been staying at our son’s place in Davidson, North Carolina. The next town up Hwy. 77 becomes a Bermuda Triangle of traffic – mornings, evenings, and weekends. Traffic lights at the freeway accesses, lights all along River Rd. past the big box stores, and for at least two blocks on each of the feeders. A typical trip will involve waiting for two cycles of each light in any direction, making passage through this area a 15-minute activity. Terrible.

Davidson has four traffic circles – one on each side of the freeway for access and two more at the major intersections coming into town. I’ve never had to wait more than a few seconds for a car or two to continue around to an exit, and generally, nothing more than a tap on the brakes is necessary to traverse all four. Similarly, Napa, California, just completed a set of three traffic circles at the intersection of First St and Hwy 29, to the same effect, smooth continuous traffic flow.

The 8 Wastes of LEAN


The main LEAN Waste here is Waiting Time – Queues and Bottlenecks, with a secondary Waste of Talent. Every traffic light causes queues, vehicles waiting for the light to decide who’s turn it is next. No matter how well sensored and programmed they are, somebody waits. And waits. And then the queue becomes a batch – a slug of vehicles moving at the pace of the slowest ones in front – to queue at the next light.

The LEAN Design Principles in action with Traffic Circles are:

  • Single Piece Flow – individual vehicles moving through the system (series of intersections) as they arrive (matching demand), basically no batching
  • Autonomy – the individuals make their own decisions about timing, pace, and direction, all within the Visual Controls
  • Visual Controls – the physical barriers (circle and entrances/exits) and arrows and guidelines


A very common real-life “in your operation” example of Waiting/Batching:


In a winery sales office, the order-processing person wanted to “make it easy for themself”, and so would print and carry the packing lists out to shipping only twice a day. This created a ‘late morning’ batch and a ‘mid-afternoon’ batch. The shipping folks had little to do before the morning batch’s arrival; and a serious crunch to have everything pulled, packed, and ready for the carriers (UPS/FedEx/etc.) to pick up at the end of the day. The waste is in the shipping folks time in the morning, and then in late shipments from the afternoon rush. Handling incoming mail in mailrooms and digitizing has been another common problem area.

What’s the solution?

In the case of the roundabouts, it takes years of  infrastructure planning – before development overwhelms the area (Davidson), or strong-willed leaders willing to acquire the necessary acreage (Napa), to avoid the Wastes of traffic signals.

In the case of Order Processing, some mapping and analysis of the “As-Is” state uncovered other hidden wastes (a desire to double-check the paper orders) and solutions implemented included process flow changes and simple physical changes – moving the printer out to the shipping area so orders are immediately available to the shipping personnel upon confirmation, with profound results.  


This example demonstrates three of the twelve design principles that we use when facilitating a re-design or new process design.  Our approach focuses on these positive principles in contrast to the 8 Wastes to more easily achieve a great design. 

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