I really like the book "This is Lean" by Niklas Modig & Pär Åhlström. I believe the book describes what Lean is, an easy and understandable way. Lean is all about flow.
I like smooth flow. It also applies to traffic. I do not like queues and unnecessary waiting.
The other day I experienced poor flow. Close to where we live there is a road construction, which means that there is only one lane. Therefore, they regulate traffic with a traffic light for a distance approximately 15 m long. That is fine!
However, is it necessary that both driving directions have red lights for one minute? At the same time.
I reacted to how long I had to wait for green light, so I decided to examine the traffic light a little closer.
It turned out that the red light had a duration of 1 min and 23 sec, while the green light had a duration of 23 sec. It provides a value-added time of 22% (23 sec / 106 sec).
I understand it is necessary to add a safety margin. However, 1-minute margin seem unnecessary. If a car drives with a speed of 20 km/h, the 15 meter drive takes barely 3 sec. 1 minute red light in both directions is an excessive margin.
It is easy to think that 1 minute is not a lot of time.
What do you think about reducing the capacity of a road to 22% of its original capacity?
What about a probability of 78% of hitting a red light?
What does this mean for all the cars passing? How much time is lost during the day? Week? Month?
If 1,000 cars normally use one hour to pass through, it now takes 4.6 hours.
By measuring and reflecting about how we spend our time, it is easier to find improvements, adjust direction and plan future activities.