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Tempo 120 sign at a climate protection demo
Photo: Sachelle Babbar / ZUMA Wire / IMAGO
When it comes to a speed limit on the Autobahn, tempers quickly boil over in Germany.
Most recently, even the Federal Constitutional Court dealt with the issue: After the traffic light coalition had rejected a speed limit on motorways, a lawsuit was filed in Karlsruhe in the name of climate protection.
According to the complainants, in order to reduce CO₂ emissions in traffic to the legally permitted level, a speed limit must be introduced.
The judges saw it differently.
It has not been sufficiently proven that a speed limit is necessary to achieve the climate protection goals.
A new study by the Federal Environment Agency (UBA) has now been published, which underlines the benefits of a speed limit.
The models show that a speed limit on motorways would save significantly more climate-damaging carbon dioxide than previously assumed by the authority itself.
At a maximum speed of 120 kilometers per hour, 6.7 million tons of CO₂ equivalent could be saved per year.
A UBA study from 2020 had put the reduction at just 2.6 million tons.
According to the current study, CO2 emissions in road traffic are reduced by 4.2 percent as a result of the speed limit.
differences in methodology
The researchers from the universities in Stuttgart and Graz and from a consulting company commissioned by the UBA explain the differences with a mix of factors.
Part of it is about the methodology: different emission factors were used for the old study.
According to the researchers, however, certain behavioral patterns of drivers also play a more important role than previously assumed.
Accordingly, a speed limit would make motorways less attractive than country roads.
"Driving is more direct, since using the motorway usually involves longer detours," says the study.
This changes the driving performance on the different road types.
The researchers are assuming a decrease of 1.1 percent in the use of freeways, while the mileage of cars and light commercial vehicles will increase on all other roads.
That also explains the decline in CO₂ emissions.
The researchers also estimate that a speed limit would make other modes of transport more attractive.
A small proportion of people will then be able to do without the car altogether and switch to the train, for example.
"The overall reduction in mileage on all route types is 1.8 percent and 2.1 percent for car traffic," it says.
However, the shift in traffic would also have consequences for local route networks.
There could be additional charges.
The traffic planners would have to redesign the networks accordingly.
Around a third of the additionally calculated savings potential can be attributed to changed routes and lower demand.
The rest comes from the changed methodology.
Other forecasts had also shown that a speed limit would also reduce the number of road deaths and noise pollution, and there would also be fewer pollutant emissions.
According to surveys, almost two-thirds of Germans would welcome a speed limit on motorways, which already exists in many European countries.
Politically, however, the project failed again and again.
Both the SPD and the Greens had anchored a speed limit on motorways in their election program.
But in the negotiations to form the traffic light coalition, the FDP opposed it.
joe
