Working on Walking

My current occupation is to work as a product manager of the microscopic traffic simulation software PTV Vissim for the PTV Group, focussing on PTV Viswalk, the pedestrian simulation of Vissim.

It was after I had finished my physics studies at Karlsruhe University (nowadays known as the southern part of KIT) in 2003 that I turned my interest at Duisburg-Essen University to the simulation of pedestrian flows and everything in relation with pedestrian dynamics. 

VISSIM is a software to simulate many - if not all - aspects of traffic which are relevant for planning purposes: motorized individual traffic (cars, HGVs), public transport, bicycles, and - of course - pedestrians, but also traffic signals, emissions. The approach taken is to represent each traffic participant by an individual entity in the simulation. That's why it's called "microscopic". The complementary approach that uses averaged properties (densities and continuous flows) as representations of traffic is called "macroscopic", well - physicists might prefer the notion "thermodynamic approach". For more information on Vissim see the youtube channel.

What is a product manager and what does (s)he do? Well, a manager tells the people what they ought do and a product manager tells the product what it is meant to do. Right? At least that's not entirely wrong, but the details of a product manager's work vary from company to company, even department to department.

The lack of a precise, general, and detailed definition can - among other things - be recognized from the fact that up to now there is no article in the German Wikipedia on "Produktmanager" and in the English Wikipedia it currently starts with a quite helpless more or less self-referring definition: "A product manager researches, selects, develops, and places a company's products, performing the activity of product management."

The reason for the confusion probably lies in some other self-reference: "The product manager's work defines the product, but the product defines the product manager's work." "together with some other factors" should obviously be added. It does so, as the work of a product manager is what remains if one peels off the production (development) process in the narrower sense from the one in the wider sense. So, it's software development without developing software. For a software product that is close to current research this implies staying in touch with the academic discussion. This is one of the reasons for my ongoing publication history - which has an extra page here - after I had finished my PhD thesis.

To me the field of pedestrian, crowd, and evacuation dynamics is one of the most exciting ones, as it includes references to a large number of research fields. Simulating the dynamics of a large number of pedestrians is challenging in terms of computation resources: The models need to be formulated and implemented in an efficient way. Collecting large amounts of data in experiments and observations is difficult, as automatic evaluation of the video footage is difficult and the algorithms have just recently been developed and are continuously being improved. Pedestrian traffic is one of the modes of traffic and transportation and therefore part of traffic planners' and traffic engineers' (optimization) work. And finally crowd behavior in dangerous or competitive situations in my eyes sheds a light on very elementary human motivations. Its analysis is interesting to psychology, sociology, human evolution history, game theory, and the philosophy of the mind. Although I do not work daily in most of these fields, I have grown interested in all of them - prompted by their relevance for pedestrian dynamics. On the web one can find a number of interesting resources on the topic like,, and