Traffic Unjammed

At Siemens, Redesigning the Future of Ready, Set, Go

traffic lights1 flickr
Well engineered traffic- light systems keep traffic moving.
  • Why it matters

    Why it matters

    There’s more to traffic lights than red, yellow and green. An expert explains the complexities of keeping traffic moving around the world.

  • Facts


    • Siemens, which sells about 40,000 traffic lights a year, has the capability to remotely access the traffic control centers of 255 cities worldwide.
    • The traffic system of the future will communicate with vehicles via WiFi. Traffic lights will be able to recognize and avoid conflicts, like developing traffic jams.
    • No matter how sophisticated a traffic system is, it cannot prevent people from jaywalking. Germans, however, are very good at waiting for the light to turn green.
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When the Siemens engineer talks about his work, people often ask about how difficult it can be to switch something from red to yellow to green. But he says plenty of mathematics, algorithms and know-how are required at various levels to optimally guide traffic flows, as well as an understanding of different cultures.

Die Zeit: When was the last time you almost ran a red light?

Wilke Reints: I don’t remember. I always step on the brakes in time when the light turns yellow.

Do you take traffic lights especially seriously because you help develop them?

Yes, it’s a matter of professional honor. I have a running joke with some of my friends. When I’m out with them and they want to jaywalk at night when there’s no traffic, I stand still and say: “C’mon guys, you can’t do that. I’m the one who makes the lights.”

There are parts of the world where traffic lights are viewed as nonbinding recommendations…

I’ve had that experience many a time. I travel to Beijing a lot on business. It’s quite possible to get run over when you walk across the street on green there. We northern Europeans are used to being able to cross the street on green without being hurt. It’s different in other countries, but people there have also learned to deal with it.

So you’re powerless, no matter how sophisticated the technology?

The traffic concept simply has to be good enough to convince people in a given place. In Germany, you could install the most outlandish traffic light circuit and people would obey it. You could bring traffic to a standstill in an entire city with chaotic circuitry. In many other countries, people simply ignore what they feel doesn’t make any sense.

How big is your department?
About 200 developers work in my R&D departments worldwide to optimize the flow of traffic under every imaginable condition. We also run a 24-hour support center for our traffic engineers. Our employees help people solve problems with their traffic light systems by loading the data onto traffic computers. We have eight full-time employees in Munich and Augsburg assigned to our time zone, as well as about 15 employees in the individual sub-regions.

Are they all engineers?

Our developers are almost exclusively engineers specializing in computer science and transportation. Our service employees are definitely people with field experience, and in their case having an engineering degree isn’t absolutely necessary.

People wait for the light to turn green in Germany, unlike New York. Source:


How many traffic lights does Siemens make a year?

Our plant in Augsburg produces about 22,000 traffic lights each year. Siemens sells about 40,000 traffic lights a year.

Is it true that you can remotely control the traffic control centers of 255 cities worldwide?

Yes, from Abu Dhabi to Vienna to Würzburg. When someone requests support from us, we can log in through secure lines in Munich and intervene directly – assuming we have the on-site approval of our customers.

So it doesn’t just go through the Internet?

For heaven’s sake, no. The individual traffic lights are never directly connected to the Internet, and the central traffic computers are only connected through certain demilitarized zones. It takes enormous effort to keep these lines secure.

What brought you to traffic lights?

I completed a training program in communications electronics at a very early age. Then I switched to traffic engineering and also got a degree in communications electronics. After that, I went into sales and worked my way through various technically oriented jobs in Germany and abroad. I spent a lot of time traveling in the Arab world. I’ve been in my current position since 2010.

What appeals to you about such an everyday object as the traffic light?

I like subjects that seem simple at first glance and yet are extremely complex. That’s completely the case with the traffic light. When I talk about my work, people often say: “Well, it can’t be that difficult to switch something from red to yellow to green…” But you can imagine the mathematics, the algorithms and the know-how required at various levels to optimally guide the flow of traffic.

Traffic is easy to predict to a certain degree, but then it tips into chaos. What makes the work so appealing is the fact that we use the tools of electrical engineering, communications technology, traffic engineering and traffic planning to solve problems, and that we do it in various countries and cultures.

But you must be inundated with complaints from people about their very own chain of red lights on the way to work and about incapable traffic planners…

…and if have plenty of time on my hands, I’m happy to tell them the whole story. Traffic planners actually give a lot of thought to their work. The trick isn’t how to get Mr. X or Mrs. Y through the road network as quickly as possible: The trick is to keep traffic moving in a part of the city where there are more cars underway than there are available roads.


Ampelmaennchen_Ost_Fahrrad commons wikimedia
The ‘Ampelmännchen’ is one of the few east German institutions adopted by the West. Source:


Traffic circles have a much better reputation than traffic lights…
I too am a fan of traffic circles. But the minute you have more cars than space on the street, the traffic circle becomes a very poor means of managing traffic. If the inner portion of the circle is jammed, traffic comes to a complete standstill in all directions. The risk becomes exponentially larger as you connect more and more traffic circles in a row.

What does the traffic light of the future look like?

It will learn how to speak and see. It will communicate with vehicles through a wireless LAN standard, and it will share information of almost any nature with them, such as information about the flow of traffic or road conditions. In practice, this will be telemetry data from the vehicle, such as data on current speed, but also on when the ABS is activated or the windshield wipers are switched on. Using this information, the traffic light will be able to recognize and avoid conflicts, such as developing traffic jams.

Do you prefer the traffic lights in eastern or western Germany?

I think the walking figure on eastern German pedestrian lights is more likeable. It seems more animated and not quite as abstract. And it’s one more reason to stop at red.

This article originally appeared in Die Zeit. It was translated by Christopher Sultan. To contact the author:

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