Under what circumstances should the vehicle speed not exceed 15?

[DelDerek]

When a motor vehicle passes through an unattended railway crossing, the speed should not exceed 15. Here is additional information: 1. No U-turns: Motor vehicles are not allowed to make U-turns at locations with no U-turn or no left-turn signs or markings, as well as at railway crossings, pedestrian crossings, bridges, sharp curves, steep slopes, tunnels, or sections of road prone to danger. 2. Common knowledge: At a crossroads, when the left-turn signal is red and the straight-ahead signal is green, you cannot make a left turn or U-turn. This is because when the straight-ahead signal is green, vehicles from the opposite direction are also going straight, and making a U-turn would obstruct the normal flow of oncoming straight-ahead traffic, which is definitely not allowed as it violates the Road Traffic Safety Law. When the left-turn signal turns green, the straight-ahead signal for the opposite direction usually turns red, making it safer to make a U-turn at that time.