Till Schmid, Transport planner at ewp, Switzerland

Increasing efficiency by letting the road users organize themselves?




My first experience with a shared space scheme was in Köniz, Switzerland. I was amazed by how well it worked and how the road users communicated with each other. It was a mystery to me why this design is not used more often, as it obviously had advantages. I tried to find quantitative criteria for the use of such schemes – without much success. That’s when I decided to dedicate my master thesis to shared space concepts and to bring light to the darkness. The main objectives were to set up a microscopic simulation of a so called “free crossing area” (FCA), to compare the results with real data and to assess capacity and traffic quality in generalized shared space-layouts.
The idea: Let the traffic organize itself
“Shared space” aims to improve the quality of streets by placing motorized and non-motorized traffic on the same level. Important elements of shared spaces are a high interaction between traffic modes, self-organized traffic by reducing regulations and the integration of social and traffic behavior in a single street layout. FCA is one possible traffic regime to design a street according to the shared space-idea. By removing all zebra crossings, pedestrians are able to cross the street freely at any point, strengthening the interaction between traffic modes. This street layout has only been used reluctantly until now, one reason being the difficulty to identify the effects of FCA in advance. For this purpose, traffic simulation offers a great opportunity, helping planners assessing different traffic layouts in an early stage.

“Get rid of regulations, pedestrian crossings, road markings and sidewalks and you end up with increased efficiency for all road users – the idea of “shared space” sounds incredible, but it actually works.”

The challenge: How do road users behave when there are no regulations?
Modelling mixed traffic is a challenge, because of the complexity of the interaction between pedestrians and cars in such schemes. In addition to that, conventional traffic simulation software is unable to simulate shared space with built-in functions. That is why I used the COM API of PTV Vissim to be able to implement non-standardized solutions. The interaction between pedestrians and vehicles is modelled based on two types of road users. Users either show “prudential” behavior (give way to other users) or “aggressive” behavior (showing no consideration for other users). The decision, which user will behave in which way, is set by conditional probabilities. In Vissim, this is controlled by event-based scripts. Calibration and validation of the model was performed based on the FCA in Köniz, Switzerland.
The result: FCAs work and can reduce delay
Results show, that, regardless of its simplifications, the simulation model is able to represent vehicle travel times and vehicle continuity very well on a high generalization level. It is accurate enough to allow a comparison of traditional pedestrian crossing designs and FCA with respect to delay and capacity. This analysis shows, that since mean delay for every user in FCA is in most cases lower than in comparison to traditional street layouts as zebra crossings, the regime should always be considered when designing a street, especially in situations of high pedestrian activity.
More about Till:
After studying Geomatics and Planning at ETH Zurich, Till decided he wanted to help design more livable places and contribute to the discussion on how our environment should look like. That is why he chose to pursue a master’s degree in Spatial Development and Infrastructure Systems.
Till started using PTV Vissim and Visum in his studies and continues to do so in his work as a transport planner at the Swiss company ewp. The range of projects he is working on varies from simple intersection modelling to city-wide analysis.
You want to get to know Till or chat with him about shared space? Just connect with him on LinkedIn.
Fancy a reading? You can download Till’s master thesis (German) and a summary (English) for free.
Get to know the PTV Expert:
Tobias Kretz, Chief Product Manager PTV Viswalk at PTV Group
Till’s master thesis is exceptional. With its impressive 200 pages it makes up for a reference work on the state-of-the-art of shared space and its modelling. With his simulation of the “free crossing area” in Köniz he also pushed PTV Vissim, as it was back then, to its limits. He made use of the COM interface. It allows users to extend PTV Vissim capabilities. If you want to learn more about it, you can watch a webinar held by my colleague Jochen Lohmiller on “Scripting in PTV Vissim Using the COM Interface”. PTV also offers dedicated COM training courses. On the way to standardize the modelling of shared space without resorting to COM usage, Viswalk 11 – which has been released after Till’s thesis in autumn 2018 – allows for vehicles to be considered in pedestrians’ dynamic potential. This way they navigate more efficiently around queued vehicles as is shown in the “What’s New in PTV Vissim & Viswalk 11” webinar.
And of course you can always visit the PTV User Forum on LinkedIn and ask experts and practitioners for advice and tips.

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