What can cause a shockwave?
Drivers experiencing a shockwave find that they suddenly have to slow down, then a few moments later they can speed up again. The causes of this ‘stop-start’ driving are varied, some are due to incidents, some are due to traffic conditions (e.g. merging at a junction), some are due to the physical layout of the road, and others appear to have no cause. Studies have shown that a shockwave occurs when the density of the traffi c reaches a critical level. Unstable traffic speeds combined with sudden braking creates a shockwave which travels back through the traffic at about 12mph.
