Several types of telematic systems are used to monitor traffic flow characteristics, traffic census performing, and traffic queue detection. The data is used for performing online traffic flow evaluations or offline traffic engineering analyses. Various types of detectors are gradually being installed along especially the D and R type roads
The goal of the systems is continuous monitoring (mostly in 5-minute intervals) of the average vehicle speed, traffic flow composition (BUS, freight automobile, passenger automobile, motorcycle), traffic density and intensity, etc. done always within a specifically defined section of the road network. The individual monitored sections are usually several kilometres long. Therefore, these systems are still incapable of monitoring the dynamic changes of traffic queue lengths over time with higher accuracy than in the given range.
This data is the base for the subsequent traffic level calculations (1 - fluent traffic, 2 - increasing traffic density, 3 - heavy traffic, 4 - traffic queue forming, 5 - traffic collapse) as well for travel time calculation to distant destinations.
Equipping long-term closures of communications with high volumes of traffic (such as during a bridge repair) with a portable surveillance system is gradually becoming mandatory in order to allow monitoring of the forming of queues upstream from the closure.
In certain large cities, the intensity of traffic on the thoroughfares shall be visually assessed through the surveillance system by a state or municipal police officer.