English: Qualitative explanation of car-following in Kerner’s three-phase traffic theory: A vehicle accelerates at a space gap ${\displaystyle g>G}$ and decelerates at space gaps ${\displaystyle g<g_{\rm {safe}}}$, whereas under condition ${\displaystyle g_{\rm {safe}}\leq g\leq G}$ the vehicle adapts its speed to the speed of the preceding vehicle without caring what the precise space gap is. A dashed region of synchronized flow is taken from Figure 4(b).