Simple mathematics can show you that lowering the speed limit for a given number of cars that depart a point over a period increases traffic density.
Yes, that's exactly the point. The purpose is to improve overall throughput. Densely packed cars travelling at a lower steady speed is more effective than allowing high speeds to then create bunching effects and standing waves in the traffic.
Pity it doesn' t work isn't it?
The reality is that all those cars are spaced out over a stretch of road, often too close, I will admit. You then drop the speed limit, for the sake of argument let us say to 50%, in a few seconds you have all the cars that were spread out over say two miles of road trying to get into one mile of road and at the same time trying to maintain a safe distance. Now we know that they didn't have a safe distance in the first place but that distance will not be halved until the traffic is down to 25% of the original speed (which will actually happen fairly quickly). At most the spacing will be reduced to 75% of the original spacing. So there you have it. All those cars can not fit into the available space and before you know it you have stop start traffic crawling along.
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