Audi Vehicles Can Now Communicate with Traffic Lights in Düsseldorf, Germany

author: Eric Walz   

Driving in urban areas with many traffic lights can be frustrating for drivers, as drivers often get stuck at a red light just after catching a green traffic light at the previous intersection. This type of stop-and-go city driving increases travel time, interrupts the flow of traffic and wastes fuel. It's a common problem in cities around the world. 

To address this problem, new vehicle technology being rolled out by German automaker Audi is helping to optimize urban traffic. 

Last week, Audi announced that the German city of Düsseldorf will become the second European city after Ingolstadt where drivers can use Audi's Traffic Light Information service, which allows Audi vehicles to communicate directly with traffic signals.

Audi drivers in Düsseldorf are able to see information from around 150 traffic lights right on the vehicle's dashboard, increasing their chance of catching what's known as a "green wave" to speed their trip and avoid getting stuck at red lights.

Audi plans to have most of the city's intersections approximately 450 out of a total of some 600 installations, will be networked by the summer. It's all part of the growing trend of vehicle-to-infrastructure (V2I) and Vehicle-to-vehicle (V2V) technology, where cars can communicate with nearby objects or to each other.

Audi is the world's first automaker to network its series-production models with city traffic lights using vehicle to infrastructure (V2I) technology. 

Audi's Traffic Light Information service is not brand new. The automaker first debuted it in August 2016 in conjunction with Traffic Technology Services (TTS), an Oregon-based service provider for connected and automated vehicle applications. It was first available on select 2017 Audi Q7, A4 and A4 allroad models equipped with Audi connect. 

Currently, its offered in the new electric Audi e-tron, and all Audi A4, A5, A6, A7, A8, Q3, Q7 and Q8 models produced since mid-July 2019 with the optional Audi connect Navigation & Infotainment package and the optional camera-based traffic-sign recognition feature.

The system works by alerting the driver to the state of the upcoming traffic light, so driver's don't have to speed up when approaching an intersection to try and catch a green light. This type of driving behavior can also be dangerous to pedestrians trying to cross the street at intersections.

Audi Traffic Light Information consists of two primary functions, Green Light Optimized Speed Advisory (GLOSA) and Time-to-Green. GLOSA provides a driver with the "ideal speed" they should be driving in order to increase the chances of catching a green light. While Time-to-Green displays a timer on the dash synced to the traffic light so a driver knows precisely when it will turn green. 

GLOSA also calculates the ideal speed a driver should be traveling at to increase the chances of the light being green when approaching the next intersection.

For example, if the system informs the driver to maintain a specific speed, the next traffic light will be reached at green. Drivers won't have to accelerate unnecessarily and they will not be stressed about whether or not they will make it through the upcoming traffic before it changes to red.

GLOSA can also suggest that a driver reduce their speed gradually about 820 feet (250 meters) ahead of the traffic light controlled intersection, so that the driver and the cars behind reach the intersection when the traffic lights turn to green. This helps to reduce the frustration of stop-and-go traffic.

If getting caught at a red light is unavoidable, which is often the case in urban areas, the countdown timer on the dash syncs with the traffic light and displays the seconds remaining until the light turns green (Time-to-Green), so a driver is not caught off guard when the light changes.

"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."

A number of studies over the past five years found that drivers move through cities more efficiently using networked traffic lights. This more efficient traffic flow also saves fuel. In a pilot project, Audi said it was able to reduce fuel consumption by around 15 percent.

Using Algorithms to Optimize Traffic Flow

Audi and its project partner Traffic Technology Services (TTS) have developed a complex analytical algorithm that calculates exact predictions from three separate sources, including the control program of the traffic signal itself, real-time data from the traffic computer, road-occupation cameras, as well as detector strips in the road surface. It also collects supplemental data from approaching buses or trams, and from the buttons that pedestrians press to cross the street.

The machine learning algorithms improves continuously and learns how the traffic volume changes throughout the day, such as the morning commuter traffic or at midday when kids leave school. The Audi vehicles themselves also help to optimize the traffic light forecasts.

"The cars send anonymized data when traffic lights are crossed to an Audi backend, which checks whether the actual crossings of traffic lights correspond to the forecast data. Only after this are the traffic lights cleared for the display in the car," Hainzlmaier explained.

In the "smart cities" of the future, city planners can use this traffic light data to address known traffic problems in specific areas. For example, if an busy intersection frequently backed up or if the red light wait times are too long, adjustments can be made to the traffic signal timing to optimize the flow of traffic.

"We aggregate the recorded data into reports that we will make available to the city authorities. Traffic lights can then be given more efficient phasing and traffic will flow better." Hainzlmaier added.

In addition to the German cities of Düsseldorf and Ingolstadt, Audi'sTraffic Light Information service is available at more than 10,000 intersections in North America with more to come. The major metro areas in the U.S. include New York, Dallas, Denver, Houston, Kansas City, Las Vegas, Los Angeles, Orlando, Phoenix, Portland, San Francisco and Washington D.C.

It includes 2,000 intersections in New York City and more than 1,600 around the U.S. capitol of Washington D.C. 

Eric Walz

Originally hailing from New Jersey, Eric is a automotive & technology reporter covering the high-tech industry here in Silicon Valley. He has over 15 years of automotive experience and a bachelors degree in computer science. These skills, combined with technical writing and news reporting, allows him to fully understand and identify new and innovative technologies in the auto industry and beyond. He has worked at Uber on self-driving cars and as a technical writer, helping people to understand and work with technology.