What does the sawtooth lane on the highway mean?

[ParkerMarie]

The sawtooth lane on the highway is a longitudinal speed bump, also known as a deceleration marking. As the name suggests, the main purpose of this lane is to prompt drivers to slow down in advance. Such lanes are typically set up before bridges, toll plaza areas, exit ramps, curves, slopes, and other locations. Additionally, they are often installed in accident-prone areas. The functions of sawtooth lanes and the classification of deceleration markings are as follows: Functions of sawtooth lanes: The function of sawtooth lanes is quite straightforward—to remind drivers to slow down in advance, as the area ahead may be accident-prone. Some curved road sections also feature such markings, usually accompanied by speed cameras. Speeding in these areas will be captured immediately. Don’t assume this marking serves a single purpose; in critical moments, it can save lives. Many drivers don’t understand the meaning of this marking and continue driving at high speeds. If an accident occurs or the road ahead is hazardous, regret may come too late. Classification of deceleration markings: Deceleration markings are divided into transverse deceleration markings and longitudinal deceleration markings. Transverse deceleration markings consist of a set of parallel white dashed lines, while longitudinal deceleration markings are a set of diamond-shaped dashed lines parallel to the lane divider, starting at the beginning of the longitudinal deceleration marking.

[XavierDella]

I often see those zigzag lanes on the highway while driving, and I'm particularly curious about what they actually mean. Later, I asked a traffic officer and learned that this design is called a variable lane or tidal lane. Its main function is to allow the road to flexibly adapt to changes in traffic flow during peak hours. For example, during the morning rush hour when there's more traffic heading into the city, the usual outbound lane can be converted into an inbound lane, which helps reduce congestion. The key is to pay attention to the large electronic signs above the lane; they use arrows to indicate the current direction. Once, I didn't notice the sign indicating a left turn and went straight out of habit, resulting in a ticket. Since then, every time I pass through such a road, I slow down in advance to check the signs. Many big cities are using this now, and I've heard it can increase speed by 20% during peak hours.

[DelMila]

When driving on the highway, I’ve also been confused by the lanes with zigzag markings in the middle. These special lanes are actually an intelligent design by traffic authorities, automatically changing direction based on rush hour. During morning peak hours, they add lanes for inbound traffic, and in the evening, they switch to outbound lanes. The most important thing when driving through is to watch the LED signs overhead—the directional arrows change in real time. If you ignore the signs and drive recklessly, you might end up going the wrong way or getting ticketed. I remember once during evening rush hour, I nearly drove the wrong way and was terrified. But now that I’m familiar with it, I think it’s great—especially on Friday evenings when it saves a lot of time heading out of the city.