Accordion effect

In physics, the accordion effect, known also as the slinky effect, concertina effect, elastic band effect, and string instability, occurs when fluctuations in the motion of a travelling body causes disruptions in the flow of elements following it. This can happen in road traffic, foot marching, bicycle and motor racing, and, in general, to processes in a pipeline. These are examples of nonlinear processes. The accordion effect generally decreases the throughput of the system in which it occurs.

The accordion effect in road traffic refers to the typical decelerations and accelerations of a vehicle when the vehicle in front decelerates and accelerates. These fluctuations in speed propagate backwards and typically get bigger and bigger further down the line, decreasing the throughput of road traffic.