The length of that q is halved, imho traffic issues are caused by one bottlenecks tailback into a junction or similar and creating a bottleneck elsewhere. its

The length of that q is halved, imho traffic issues are caused by one bottlenecks tailback into a junction or similar and creating a bottleneck elsewhere. its like bandwidth. you are keeping twice the bandwidth up until the last possible moment, meaning the bottle neck is going to be "fed" as efficiently as possible with half the chance of causing a knock on effect elsewhere. but this is not just a german thing.. in the UK there is a curved arrow sign on the road where one lane ends meaning "merge in turn" you will also see signs saying: "use both lanes" and "merge in turn" (but as text) which are all the same thing. you will often see it say after a junction or roundabout where maybe 200m later the road goes from two to one lanes. encouraging you not to just queue right through the previous junction and block that up too.