It is often said that simple things that we may not be even aware of can have significant consequences. Arrows on highway signs, for example. Research shows that when they point up instead of down they give drivers a feeling of being more informed and having more time to react. Rijkswaterstaat, the Dutch ministry of infrastructure and the environment, has been studying this issue since as far back as 2008. A trial conducted on the highway at the Velperbroek junction near Arnhem indicated that using upward-pointing arrows can improve traffic flow by up to 10 kilometres per hour and reduce traffic delays by up to 30 minutes. Since then, the Netherlands have changed most of their signs to use upward-pointing arrows, and so have Sweden and Germany. Neighbouring Belgium is currently in the process of studying the effects of reversing the arrows, while most other countries, including the US, UK, Canada, France and Spain still use downward-pointing arrows.
by Peter Biľak
https://worksthatwork.com/artefacts/upside-down
