The German Environment Agency (UBA) recently calculated the impact of a universal speed limit on Germany highways on carbon emissions in a prominent study. Thereby, it was shown that a universal speed limit of 130 km/h reduces emissions by 1.9 Mio. t CO2-equivalents per year. Speed limits of 120 and 100 km/h lead to reductions of 2.6 and 5.4 Mio. t. The UBA concludes from these numbers that a universal speed limit can contribute to emission targets in the traffic sector at „negligible additional costs“. In contrast, the author shows that increasing times of travel resulting from reduced speed lead to substantial additional costs. Taking into account these costs, he calculates that the speed limits considered by the UBA yield abatement costs ranging from 716 to 1382 EUR per ton CO2-equivalent which is rather high compared to alternative climate protection measures. Even if the reduction of traffic fatalities is taken into account, universal speed limits between 100 and 130 km/h can be shown to lead to welfare losses. The author concludes that transport policy should focus on measures which yield emission reductions at acceptable costs. Promising alternatives are a general carbon price for all sectors, variable speed limits and road tolls depending on position and time.
The paper is written in German.