To understand when driving at an **abnormally reduced speed**, it is important to know the concept of **minimum speed**. The minimum speed is the lowest speed at which one must drive on a specific road. If a vehicle is driving below this minimum speed, it is considered to be at an abnormally reduced speed. For example, if on a highway the minimum allowed speed is 60 km/h and a vehicle is driving at 40 km/h, it is driving at an abnormally reduced speed.

It is crucial to respect speed limits, both maximum and minimum, to ensure road safety. Driving at a speed lower than the minimum allowed can be dangerous, as it may cause risky situations for other drivers who do not expect to encounter such slow vehicles on fast roads.