Air pollution control thanks to optimised traffic light management

The traffic management centre SIRAC in Strasbourg: Thanks to PTV’s simulation software it was possible to illustrate how signal control optimization can help improve air quality (Photo: SIRAC).

Germany’s top administrative court has ruled that diesel cars can be banned from cities, which will spur the discussion about urban air quality. However, air pollution control is a red-hot topic elsewhere, too. Strasbourg is becoming the first city in France to optimise its traffic light management in order to cut emissions. In this interview, our Vice President Project Management & Services Frédéric Reutenauer explains the PTV Group’s role in this project.

Compass: Frédéric, Strasbourg has taken an interest in the topic of clean air for a few years now…

Frédéric Reutenauer: Yes, there’s been an air pollution control programme in France since 2015 and Strasbourg is working on a specific action plan called “Strasbourg – Ville et Métropole respirable”. In translation, it means something like “Breathable City and Metropolitan Region”. Stop-start traffic is a major problem in cities. The constant stopping and re-starting on congested streets leads to huge increases in emissions. One of the programme’s specific measures therefore involved scrutinising the opportunities to improve road traffic management, and more precisely traffic light management.

Compass: So there are fewer emissions if traffic flows better at traffic lights?

Frédéric Reutenauer: Precisely. Optimised traffic light management significantly reduces the number of stops and starting manoeuvres needed and thus significantly reduces polluting emissions. We can see the real-life effects of this by taking the example of Avenue de Colmar – one of the main traffic routes to the south of the city, with six major crossroads – shown in a simulation using our program PTV Vissim. The waiting time for all road users at traffic lights controlled by our software solution PTV Epics was less than 45 seconds in 85 per cent of cases. This figure is currently 35 per cent.”

Compass: And what about emissions? What were the results there?

Frédéric Reutenauer: Thanks to optimised traffic light management, our simulation shows nine per cent fewer vehicle stops, eight per cent lower nitrogen oxide emissions (NOx) and nine per cent lower emissions of PM10 particulate matter. At present, no other measures achieve such a significant effect.

Compass: But what exactly is the difference between traffic light switching using PTV Epics and Strasbourg’s previous traffic light management system?

Frédéric Reutenauer: As in many other cities, the tram takes precedence over all other road users in Strasbourg. Traffic lights for the tram currently turn green as early as possible – often up to 15 seconds before it actually reaches the traffic light. In contrast, PTV Epics switches the time slot to suit requirements in real time, ensuring that no ‘green time’ is lost and that enough room is freed up for other road users.

Frédéric Reutenauer, Vice President Project Management & Services at PTV Group, supervises the Strasbourg-based project on the PTV side (Photo: PTV)

Compass: How labour-intensive is it?

Frédéric Reutenauer: It’s very easy to start running this function. Our software is incorporated into the existing system as an additional component. It’s really simple to set up and operate.

Compass: Following the good results in the simulation, will the whole thing now enter the practical phase?

Frédéric Reutenauer:  Yes, we have integrated PTV technology into the control device manufacturer FARECO’s systems at the node points on Avenue de Colmar. The test phase is due to last until summer and then there’ll be a decision about other areas of the city in which the new traffic light system should be rolled out.



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