An attenuator, used to transform the impact of a car speeding into a roadworks site by crumpling. The right part will fold like a harmonica for very slow impacts, while the middle yellow section will collapse like a crumple zone in a car. The whole assembly is always mounted on a truck (raised up when not in use), which also provides the main mass slowing down the moving car by being pushed forward on impact (at higher speeds, not all energy can be absorbed in the attenuator). Shown near intersection roadworks in Auckland City, New Zealand, at the bottom of Nelson Street.