The green wave

It’s a dream harboured by just about every city motorist. You glide through the traffic, hitting green light after green light without raising a sweat. No stop start, no racing to make the light as it changes, but just the feeling of surfing a ‘green wave’ through town.

Okay, so depending on the size of the town, the population and number of cars on the road, a completely seamless journey might  remain something of a stretch, but with Audi’s vehicle-to-infrastructure (V2I) service and the ‘Traffic Light Information’ motorists are in a far better position to know when the lights will change and what (legal) speed they need to maintain to make the next green, and the next and the next.

From July this year, Audi will network new models with the traffic lights in its home town of Ingolstadt and then roll the technology out to include more European cities from 2020 onwards. 

The technology and its implementation is not new, but has been in limited use in Germany for some time. Audi has conducted extensive trials in a number of German cities, beginning with Berlin where it has been a limited pilot project for several years.

In the USA too, Audi customers been using this service since late 2016 and Audi is the first manufacturer worldwide to network its series-production models with traffic lights in cities. 

“Stop-and-go traffic in cities is annoying. By contrast, we are pleased when we have a 'green wave' – but we catch them far too seldom, unfortunately. With the Traffic Light Information function, drivers are more in control. They drive more efficiently and are more relaxed because they know 250 metres ahead of a traffic light whether they will catch it on green,” says Andre Hainzlmaier, head of Development of Apps, Connected Services and Smart City at Audi. 

“In the future, anonymised data from our cars can help to switch traffic lights in cities to better phases and to optimise the traffic flow.” 

In America, more than 5000 intersections in Denver, Houston, Las Vegas, Los Angeles, Portland and Washington are linked to the Traffic Light Information function. Here, Audi has also introduced what it calls GLOSA or ‘Green Light Optimised Speed Advisory’ which shows to the driver the ideal legal speed for reaching the next traffic light on green. 

This function and ‘Time-to-Green’ countdown will both be used when the system is up and running in Ingolstadt shortly and will be activated on all Audi e-tron models and the A4, A6, A7, A8, Q3, Q7 and Q8 to be produced from mid-July.

The reason it has taken two years longer to get the system up and running on a larger scale in Germany than in the USA is simply a matter of logistics. 

“The challenges for the serial introduction of the service are much greater here than, for example, in the USA, where urban traffic light systems were planned over a large area and uniformly. In Europe, by contrast, the traffic infrastructure has developed more locally and decentrally – with a great variety of traffic technology,” explains Hainzlmaier. “How quickly other cities are connected to this technology depends above all on whether data standards and interfaces get established and cities digitalise their traffic lights.” 

Audi is working to offer Traffic Light Information in further cities in Germany, Europe, Canada and the USA in the coming years. In the large east Chinese city of Wuxi, Audi and partners are testing networks between cars and traffic light systems in the context of a development project. 

In future, Audi customers may be able to benefit from additional functions, for example when 'green waves' are incorporated into the ideal route planning. It is also conceivable that Audi e-tron models, when cruising up to a red traffic light, will make increased used of braking energy in order to charge their batteries. Coupled with predictive adaptive cruise control (pACC), the cars could even brake automatically at red lights. 

In future, V2I technologies like Traffic Light Information will facilitate automated driving. “A city is one of the most complex environments for an autonomous car. Nevertheless, the vehicle has to be able to handle the situation, even in rain and snow. Data exchange with the traffic infrastructure can be highly relevant here,” says Hainzlmaier.