What helps to reduce traffic bunching on a motorway?
Traffic bunching and variable speed limits
In an Exeter University study reported in the Independent:
They discovered that under certain conditions, when cars are bunched in a specific density and travelling at a specific speed, a single driver over-reacting can set off a braking shockwave that will build momentum and travel back along a motorway for miles.
Variable speed limits, which can be controlled manually or automatically, can help reduce this type of effect which can be quite significant. Below is a very short video in which scientists recreate traffic bunching on a circular road.