European authorities are exploring the possibility of reducing speed limits on motorways to curb carbon emissions. In 2019, the Dutch government enforced a daytime limit of 100 km/h on their motorways, and some Austrian regions have followed suit. A team of Austrian transport scientists advocate for the implementation of a 100 km/h speed limit to decrease the sector’s environmental impact. German scientists have also recommended a similar limit after a study by the country’s environmental agency demonstrated that a speed limit of 120 km/h could decrease road traffic emissions by 2.9%. Road transport already accounts for one fifth of total EU greenhouse gas emissions as well as more than three quarters of global transport emissions.
A lower speed limit results in less required fuel because of lower air resistance, and consequently, less carbon emissions. Additionally, a speed limit would reduce noise, particulate pollution, nitrogen, and enhance commuter safety. Electric vehicles, which do not emit gases, would be exempt from the speed limit, but this exemption is not recommended, as electric vehicles’ energy requirement increases with speed.
The effect of a speed limit on a systemic level is still uncertain; the reduction of travel time could encourage people to travel by train, particularly for longer distances. Furthermore, implementing a speed limit could lead to a more regular flow of traffic, fewer traffic jams, and, as a result, an increase in average speed. While some individuals have opposed the proposed speed limits, calling them negligible or violating citizens’ freedom to drive fast, the reduction in emissions from a speed limit is equivalent to 30-50% of the current difference between Germany’s emissions and its climate goals for this year.
A speed limit, however, is only one measure that contributes to emissions reduction; improving electric cars’ energy efficiency and public transport modalities are also essential. Ensuring that the speed limit is uniformly enforced and that the public is aware of how they can save money by consuming less fuel or electricity is also crucial. Therefore, adjusting the message to suit the locality is critical; some communities will prefer weather signals, while others may prefer safety messages.