Is there a speed measurement at the ordinary traffic lights?

Speed measurement is usually available at traffic lights. The camera at the intersection of traffic lights doesn't look like radar, but it doesn't mean that there is no speed measuring function, and speeding can also be detected.

At present, more than 80% of the speed measurement of urban roads in the world is completed by ground loop, which is an induction coil buried under the road, just like a mine. I can't see it underground, but there are wires. Press it and there will be a reaction. How long does it take to press it between two wires, and the speed can be measured immediately.

The camera at the intersection can also capture violations. In addition to speeding through the red light, the solid line changing lanes and pressing the line can also be photographed. The capture efficiency can reach more than 95% during the day and 90% at night, because it has night vision function.

Extended data:

Vehicle speed measurement method:

1, coil speed measurement

This method is classic and the detection effect is good. For example, this method is widely used in southern China, such as Shanghai and Guangdong. According to the speed of the vehicle passing through the parallel coil, it is judged whether the vehicle is speeding, and the camera is taken to collect evidence.

The disadvantage of this detection method is that the construction of the induction coil buried on the ground is large, and once the road surface is changed, the coil needs to be buried again. In addition, in the high latitude freezing period and the low latitude summer road surface and the poor road surface quality, the maintenance workload of the coil is huge. ?

2. Video detection

This method tracks the process of illegal vehicle behavior through the analysis of continuous video images, and captures illegal vehicles through the analysis and control of photos. The advantage of the system is that it is not limited by road conditions, and the installation does not need to destroy the road surface, nor does it need to bury the induction coil under the road surface. It is a new generation of road vehicle detection method to detect traffic data by setting a camera above the road.

The disadvantage of video is that it is difficult to identify moving vehicles. On the one hand, shooting high-speed vehicles requires a fast shutter (at least 1/3000PX), enough pixels and image algorithm;

On the other hand, at intersections, crossings and highway entrances and exits, the speed is generally slow, and common violations include running red lights, crossing the line illegally and choosing the wrong lane. These behaviors can be monitored without radar and high-speed cameras, and the purpose can be achieved by using a slow shutter. In addition, video technology is influenced by light and weather.

3. Microwave radar

As mentioned above, unlike video detection, intersections are usually multi-lane and have the complexity of multiple vehicles and pedestrians. It is difficult to detect illegal vehicles at intersections only by using microwave radar with Doppler effect.

For high-speed and one-way highways, microwave radar is the best partner to cooperate with high-speed cameras. The high-speed camera receives the high-speed vehicle detected by microwave radar, and quickly enters the snapshot state, and cooperates with the high-speed shutter to collect evidence of violation. The mainstream product in the world is that radar cooperates with high-speed camera to shoot overspeed.

Baidu encyclopedia-principle of speed measurement