On which roads are various speed measuring methods generally used?

Its principle is to hit your car with microwaves of various frequencies, and measure the speed according to the reflection time, which is divided into two types: fixed and mobile. Moving is a common mobile speed radar hidden on the roadside and installed on police cars. Fixed type is generally installed in dangerous areas such as bridges, intersections and tunnels. Radar speed measurement is often used in highways, national highways and surrounding areas of cities. At present, all mobile speed measuring radars of China police use microwave radar to measure speed, and the total application of electronic eyes exceeds 80%. Radar velocimetry has been used internationally for more than 20 years, with mature technology and low cost. Judging from the current situation, all major cities and expressways in China have forward and reverse radar speed measuring devices, and most of them are forward speed measuring devices on expressways. Reverse speed measurement means that the direction of radar wave and camera is consistent with the direction of the car. When the car is speeding, the camera shoots the rear license plate of the car. The forward speed measurement is the opposite.

2, magnetic induction coil speed measurement

Its principle is to bury two pressure sensors on the road surface and judge the speed according to the time when the front and rear wheels pass through the sensors. Common traffic lights on national highways and cities. This speedometer is easy to identify, it is rod-shaped. During driving, you can see the camera point from a distance with the naked eye, especially at night, and there are bright searchlights on. When you see the rod-shaped photo spot, just brake and slow down. This method is generally common in the entrances and exits of cities, and every car entering and leaving the city is photographed and monitored to facilitate police investigation. Since this system will not emit any radar microwave, all radar detectors in the world will not give an early warning to this system at present.