In his line of work, Frank Helbing can’t please everybody. The advisor at the main traffic office in the German city of Erfurt is responsible for deciding whether cars can sail through the city in a line of green or have to stop at frequent red lights, giving pedestrians the right of way.

“Anyone who thinks we can work magic is plain wrong,” he says.

Helbing’s work revolves around a tough dilemma – who, in the end, ultimately has the top priority at crossings? Is it cars, so they emit less carbon dioxide, or is it pedestrians, or perhaps even buses and trams?

Either way, top-level German politicians are claiming the issue as their own.

Germany’s Federal Ministry of the Environment sees intelligent traffic lights as a key opportunity to decrease air pollution.

Helbing’s workplace contains several monitors, with a large map on the wall showing the streets of Erfurt and indicating all of its traffic lights – 255 in all. “In 1989, there were only 78,” explains deputy traffic director Frank Rupprecht.

In the 1990s, 20 new sets of traffic lights were added each year and, according to Rupprecht, many of them are starting to get old.

“One in five sets is more than 20 years old,” he notes. The cost of replacing these lights is estimated at more than €20mil (RM94.7mil).

Germany’s Ministry of the Environment wants to help out with investments such as these. According to a ministry spokesman, €6mil (RM28.4mil) of European Union funds have been made available for “intelligent traffic light control”, ensuring that vehicles emit less harmful gases into the atmosphere and improve air quality in cities.

In addition to Erfurt, which is already home to two pilot projects, other cities in the region have shown interest in the project, including Jena, Weimar, Suhl and Gera.

“The focus on air quality is in order to comply with EU-wide regulations,” says Uwe Plank-Wiedenbeck from the Bauhaus University in Weimar.

Plank-Wiedenbeck, a professor of traffic systems who is leading the Erfurt pilot project, says unfavourable weather conditions play a big role in emissions caps being surpassed.

In such cases, traffic could be shifted to different places at different times.

Plank-Wiedenbeck envisages a situation in which cars on the outskirts of Erfurt could be stopped at traffic lights so that not too many cars enter the city centre at once.

He refers to these spots as “gatekeepers”, and doesn’t worry that traffic problems may result.

“There aren’t enough cars on the road to create long traffic jams,” he notes, adding that the strategy would only apply on days with a poor air quality index.

“The goal is to reduce traffic at certain times, by some 10% to 20%.” Drivers would be able to park their cars in parking lots and enter the city on buses and trams.

Helbing also hopes to see a positive impact. “When buses and trams take precedence at crossings, drivers will see that it is faster to take public transport.”

In Erfurt, it is often the case that traffic lights turn quickly from green to red when a tram or a public bus approaches, thanks to sensors at the traffic lights.

Others sensors, meanwhile, measure how many cars and trucks travel into the city to regulate traffic at crossroads.

traffic lights

On Leipziger Strasse, a main artery used by many commuters on their way to work in the city, there are early morning and afternoon programmes, explains Rupprecht. “The traffic lights are programmed in such a way that traffic stops as little as possible.”

The facilities at the city exhibition grounds are also set up so that traffic to and from the parking lots can flow more quickly during concerts or trade fairs.

Other special programmes exist for Erfurt’s Christmas market, which attracts hundreds of thousands of visitors.

And the experts at the traffic control centre aren’t just looking at traffic on wheels. “We should also make sure pedestrians don’t wait too long at red lights,” says Rupprecht, “otherwise, they will get impatient and simply run across the street.”

The green phases also have to be long enough for visually impaired people or elderly pedestrians to cross the road before the light changes again, with specific timings programmed into the traffic lights themselves.

“Drivers in Erfurt can usually enjoy a string of green lights,” says Helbing. “However, this is only if a certain load is not exceeded.”

That means no more than 40 cars can go through a green light at once. Any additional cars that reach the traffic light will have to be patient and wait at a red once again. – dpa/Christian Thiele