The junctions that generate the work
Hanger Lane gyratory, the Chiswick roundabout and flyover, the Hogarth roundabout and the Hammersmith gyratory all combine heavy volume with multiple lanes of merging traffic. Shunts here are common and often involve more than two vehicles.
They are also difficult places to recover from. There is rarely a safe place to stand, loading has to happen without blocking a live lane, and on the flyovers there is no hard shoulder at all. Getting the vehicle to a side road first — if it is driveable and it is safe — makes everything that follows easier.
