What’s used to reduce traffic bunching on a motorway?

Question topic: ,
A: Variable speed limits
B: Contraflow systems
C: National speed limits
D: Lane closures
View hint

Congestion can be reduced by keeping traffic at a constant speed. At busy times, maximum speed limits are displayed on overhead gantries. These can be varied quickly, depending on the amount of traffic. By keeping to a constant speed on busy sections of motorway, overall journey times are normally improved.


Looking for a better way to track your progress?

With so many questions, it's hard to remember which ones you've covered.

PRO membership lets you easily track which questions you've completed.

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.


Question topic: ,