How does navigation software know the countdown of traffic lights?

How does navigation software know the countdown of traffic lights?

There are actually two sources of data for traffic light countdown. 1 model was obtained directly from the traffic control department.

Those who cooperated with the traffic control departments earlier, such as Yantai City, Yantai Traffic Police and Gaode Map, cooperated to push the traffic light status to every traffic participant, Qilu.com reported on 2019. On June 5438+1October, 2023, Xi Daily also reported that Xi 'an traffic police and Baidu map deeply integrated the lighting status data of Xi's safety ball intelligent traffic lights, allowing mobile phones to display the traffic lights in seconds.

Simply put, it is to get data directly from the source, just like getting reference answers directly from teachers. As long as the mobile phone network is normal, the countdown is basically very accurate. Navigation software predicts itself through big data.

The second way is that the navigation platform uses big data to calculate the vehicles parked at the intersection, and can also calculate the approximate countdown time of the traffic lights.

Master thesis of Nanjing University of Science and Technology, real-time traffic information acquisition and display system based on mobile terminal. It says: Through the GPS positioning system in the car, such as our mobile phone, we can collect information such as the position and speed of the driving vehicle. Then it is uploaded to their control center through wireless network, and the control center analyzes and processes it to get an average traffic flow information.

This principle is used to obtain real-time congestion on general roads. By the same principle, we can actually get the countdown of traffic lights.

The product manager of Gaode Map once said: Understanding the behavior of users at intersections and analyzing the laws of intersections can promote the countdown of traffic lights.

Moreover, an invention patent of Gaode Software Co., Ltd., CN 1 14463969, is a "mining method of traffic light cycle time, electronic equipment and computer program product". There is an algorithm patent mentioned above: according to the vehicle trajectory data, calculate the time difference between the first car start sample and other car start samples.

Then analyze the differences in different time periods within a day or more, and get a traffic light cycle at an intersection. For example, the data shows that every day from 6: 00 to 7: 00, the first car leaves at a certain intersection and the last car stops at the traffic lights, with a time difference of 40 to 45 seconds.

You can roughly judge the change period of the straight traffic lights. Sampling and calculating at the same time every day can finally calculate the traffic light time at this intersection, which is more accurate. Then calculate the different traffic light periods between rush hour and night time, and finally get a full-day traffic light period.

However, there may still be some errors between the calculated results of this big data and the actual traffic light results. In actual use, you will find that some intersections have countdown, and some intersections do not.

It may be because the traffic volume and the number of samples at these intersections are relatively small, which is not enough to calculate the specific cycle, or because there are not many people at this intersection, so it is not displayed.

What's the use for us?

The principle of listening is reasonable and quite reliable, so what does this countdown have to do with us? What does it mean to our drivers?

First of all, it can prepare distracted drivers in advance. If you have experienced this function, you should be a little impressed. When there are 3 or 5 seconds left in the countdown, the mobile phone will sound a prompt.

If a friend waiting for a red light is chatting and drinking water, it can play a role of reminding and prepare for driving in advance. This countdown not only serves as a reminder, but also makes drivers in line react faster, thus improving the overall traffic efficiency of the road. For example, sometimes the car in front is not big or the queue is really long, so we can't see the traffic lights in front.

With this, don't worry too much. You can watch it on your mobile phone, right? Zou Hui published a paper "The Influence of Countdown Signal on Traffic Characteristics at Signalized Intersections" in Journal of Shandong Jiaotong University.

In the future, it can remind distracted drivers when waiting for traffic lights, and also help traffic efficiency at intersections.

Based on the similar principle, some navigation software put forward the suggestions of green light countdown display and green wave speed, which are also very easy to use. Interested friends can try it.