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Audi Traffic Light Information: driving connected to the city

4.2.2020
Audi Traffic Light Information: driving connected to the city

By networking the city traffic lights so that they can ‘talk’ to cars, the Audi Traffic Light Information project increases safety on the roads and boosts efficiency, reducing consumption by up to 15%.

After Ingolstadt, Audi is introducing its Traffic Light Information service in Düsseldorf. The project uses Vehicle-to-infrastructure (V2I) technology to connect cars to the infrastructure, enhancing efficiency and safety.

Since the end of January, Audi drivers have been able to see information from around 150 traffic lights in their cockpit, thus increasing their chances of catching a “green wave” and reducing journey times. The next few months will see a significant increase in the number of networked traffic lights - around 450 out of a total of some 600 installations by early summer.

The ideal speed

Audi Traffic Light Information consists of two functions: Green Light Optimised Speed Advisory (GLOSA) and Time-to-Green. GLOSA calculates the ideal speed for getting a “green wave,” indicating the proper speed (within the applicable limit, obviously) to reach the next traffic light at green. Consequently, drivers do not have to accelerate unnecessarily, they are not stressed, and they drive more safely.

GLOSA can also suggest reducing speed gradually about 250 meters ahead of the traffic light so that the driver and the cars behind reach the intersection when the lights turn to green. This reduces uneconomical stop-and-go traffic, a major contributor to increased consumption.

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Reducing consumption by 15%

If stopping at a red light is unavoidable, the Time-to-Green function is used. It works by displaying a countdown with the seconds remaining until the next green phase begins. Drivers can relax, take their foot off the gas pedal and save fuel.

A number of studies have concluded that drivers move through cities more efficiently thanks to networked traffic lights. In a pilot project, Audi was able to reduce fuel consumption by 15 percent.

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Precise predictions

With Audi Traffic Light Information we wish to improve convenience for drivers, increase traffic safety and encourage an economical style of driving that looks ahead,” says Andre Hainzlmaier, head of development for Apps, Connected Services and Smart City at Audi.

To do this, we have to predict precisely how traffic lights will behave in the next two minutes. At the same time, exact forecasts are the biggest challenge. Most signals react variably to traffic volume and continuously adapt the intervals at which they switch between red and green”.

The analytical algorithm

Audi and its project partner Traffic Technology Services (TTS) have developed a complex analytical algorithm that calculates exact predictions on traffic light behaviour using data from three sources: from the control program of the traffic signals; from the real-time data of the traffic computer, a combination of road-occupation cameras, detector strips in the road surface, data on approaching buses and trams, and buttons that pedestrians press; as well as from historical data.

The forecast algorithm improves itself continuously and learns how, for example, the traffic volume changes in morning commuter traffic or at midday when schools close.

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An intelligent fleet

The Audi fleet obviously plays a decisive part in optimizing traffic light forecasts. “The cars send anonymised data when traffic lights are crossed to an Audi backend, which checks whether the actual crossings of traffic lights correspond to the forecast data,” Hainzlmaier explains.

The service will evolve in future, allowing cities to also receive useful information about their traffic light infrastructure. The data can show, for example, whether cars stop too often at a particular intersection or whether the average waiting time is comparatively long.

We aggregate the recorded data into reports that we will make available to the city authorities. Traffic lights can then become more efficient and traffic will flow better”.

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From Las Vegas to New York City

Audi Traffic Light Information made its debut in 2016 in Las Vegas. Today the V2I service is available at more than 10,000 intersections in North America, including some 2,000 in Manhattan/New York City and more than 1,600 around the capital, Washington D.C.

Audi is also the world’s first automotive manufacturer to network its series-production models with traffic lights. The service operates in all Audi e-tron, A4, A5, A6, A7, A8, Q3, Q7 and Q8 models produced since mid-July 2019. The pre-requisites are the Audi connect Navigation & Infotainment package and the optional camera-based traffic-sign recognition.

SourceAUDI AG

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