The "car-following method" and its application in Nanjing traffic control

The so-called "car-following speed-measuring method" (CFM) is a traditional method for surveying vehicle speed. It is mainly used for surveying vehicle running speeds, delays due to stopping, and queuing length while waiting to pass on a road (including at junctions). Improvement to the traditional surveying method by combining a car sensor with a computer greatly simplifies the surveying operation, and enhances convenience so that the Surveying work becomes a day-to-day process. Furthermore, the cost of such a surveying method is less than other methods. The method has been widely used in traffic control of the urban roads in Nanjing since 2001. This includes surveys of the speed of motor vehicles on roads and control of traffic signals. In addition, design and checks of the "green wave" effect, and the distribution level of auto-exhaust pollutant sources, can be known if vehicle flow information is available. Increased amounts of surveying data may allow greater control over urban road traffic performance.