What does speed detection mean?
3 Answers
Mobile speed detection vehicles parked on the roadside use movable speed detectors that can be freely adjusted in direction, allowing them to capture speeding vehicles from different angles. This means they can photograph both rear and front license plates, with the only difference being the parked position of the speed detection vehicle and the direction of the speed detector. Below is relevant information about speed detection: Speed detection methods: Highway section speed detection involves setting up two adjacent speed detection points on the same road section. By measuring the time it takes for a vehicle to pass between these two points, the average speed of the vehicle on that section is calculated. Based on the speed limit standards for that section, it is determined whether the vehicle is speeding, making the process more scientific and fair. Principle of section speed detection: On highways, there are typically two cameras placed at a certain distance apart, usually covering a 30-kilometer section. When a vehicle passes both cameras, electronic equipment records the time taken to traverse this distance, thereby determining whether the driver was speeding.
When I first started driving, I also didn't understand what those machines on the roadside were doing. Speed detection is actually those square boxes or devices held by police officers, used to catch if cars are going too fast. Those poles with flashing lights on highways, or small boxes hidden in bushes near schools in urban areas, all serve this purpose. Pay special attention when passing under bridge piers, as some speed cameras are hidden in the shadows. The principle is to measure vehicle speed using radar waves or laser reflection, and they can spot you from far away. If you accidentally exceed the limit by 10 km/h, a warning text will immediately pop up on your phone. Exceed by 20% and you'll be waiting for point deductions and fines.
From a technical perspective, speed measurement can be divided into active and passive forms. The most commonly used active method employs radar waves to calculate vehicle speed by measuring frequency changes, with an accuracy of approximately ±3 km/h. Laser speed guns, on the other hand, determine speed by calculating the time difference between emitted and received light beams, resulting in smaller errors. Passive methods, such as induction loops embedded beneath the road surface, trigger timing when a vehicle passes over and causes changes in magnetic flux. It is important to emphasize that law enforcement equipment must undergo regular calibration, and speed measurement results with excessive errors are considered invalid evidence. For daily driving, it is advisable to activate the electronic dog function in navigation software to anticipate speed measurement points in advance.
