2019 / Integrated mobility technologies

Arrive more relaxed: on the green wave

    7 am at the center of Munich: The cars stand side by side and the vehicles move slowly along the asphalt. I am stuck in the middle of the morning rush hour. The traffic light changes to green. Slowly we move forward. I accelerate because I want to take the green wave with me. Further on a traffic light enters my field of vision, which has been green for two long. I accelerate a little to take along the green phase. Then the traffic light suddenly changes to yellow and finally to red. I jave to brake somewhat abruptly and stop.

    Relaxed arrival: Traffic light info online

    This situation is surely familiar to some. Sometimes it works with the green wave, sometimes not. If you knew before whether a traffic light was red or green, you would arrive at your destination more relaxed and efficiently. Audi develops this technology with its subsidiary AEV and the support of PSW: Traffic light info online.


    The first available function is called ‘Timeto- Green’. In the Audi virtual cockpit or head-up-display the driver sees whether he/she has reached the next green traffic light within the permitted speed. If this is not the case, there is a countdown to the next green phase. The driver can take their foot off the pedal early. Pilot projects in Europe have shown that car drivers are more foresighted when driving thanks to the information about the traffic light function, which positively influences the traffic flow and reduces consumption.

    Looking ahead: traffic light information online

    Modular development

    The experts of PSW support Audi and AEV in the development of traffic light info online, while bringing their competences to the module development and functional validation. One of these experts is Dr. Christian Steen. He has been involved in the project since 2011 and experiences the early days in the US: ‘Audi and AEV first showed the technology at the CES 2014 in Las Vegas’, recounts the software developer. ‘Before the trade fair started I was with the AEV project manager on site and together we prepared the vehicles for the fair. The presentation was a great success and Las Vegas was also the first town in which traffic light info was used.’

    The module must make a prognosis with active routing

    Dr. Christian Stehen

    When the technology has been rolled out across the board, we will have taken an important step towards autonomous driving

    Tobias Zimmermann

    Christian is responsible at PSW for the module development. He writes the programme, which shows the driver the necessary information in the display. What traffic light is relevant to the driver? How long does the green phase last? What speed is necessary for the driver to cross the green traffic light?

    In a first step Christian developed the different algorithms of the module over several months. A huge challenge was the fact that there were many crossing variants and the algorithm must be able to display each of these. ‘When the driver approached a simple crossing and indicated to the left, it is clear that the left turn traffic light is displayed to him’, says Christian. ‘However, there are also complicated variants, for instance a double crossing. At this point the module must make a prognosis as to which left turn traffic lights are relevant for the driver. This is a complex task during the development.’

    To provide the driver with this information Christian implements different interfaces in the module. The module receives the data of the vehicle system via the interface, for instance the vehicle position or speed. In addition, the module uses an additional interface on the internet to request the current traffic light switches. On the basis of this data the algorithm finally calculates the information displayed.

    Ensure prognosis quality

    Tobias Zimmerman is also part of the PSW team. He is working together online in the development of traffic light info. The qualified electrician has worked at PSW over the past year since October and looks after the functional safeguarding. ‘In the USA thousands of traffic lights are integrated with the technology’, he says. ‘On average every traffic light has approximately 40 to 50 crossings per day. Therefore, large amounts of data come together quickly which we must evaluate, to ensure the prognosis quality.’

    This means that Tobias assesses whether the prognosis, which concerns the traffic light info online, conforms to the actual traffic light switching. Tobias works with the GPS positions of the vehicles, the crossing times and the prognosis of the traffic light switching made for the analysis. So that the data is evaluated as quickly and efficiently ly as possible, the system, with which Tobias works, evaluates the data using the criteria previously set. In addition he and his colleagues work to further automate the evaluation

    ‘I look forward to making a contribution in developing traffic light info online’, says Tobias. ‘When the technology has been rolled out nationwide, we have taken an important step towards autonomous driving.’

    “When the technology is rolled out nationwide we have taken an important step towards autonomous driving”, Tobias Zimmermann.

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