All signal-controlled junctions in Vilnius City are managed adaptively (in accordance with the current transport flows) in order to use the time in the junctions as efficiently as possible and to ensure that the traffic flow capacity is as high as possible. Moreover, the traffic situation is periodically monitored and evaluated; upon receiving the results of conducted analyses, changes of signal control and management programs are made. 🚦

In order to understand the principles of traffic signal control systems, we have to know the methods of traffic management

Fixed mode of the intersection

The fixed mode of the intersection – the mode of operation where the intersection operates according to a predetermined signal program and the duration of the green signal in each signal group does not change strictly. This type of application is applied in case of junction failure. In normal times, intersections always operate in a flexible mode based on traffic sensors.

Intersection flexibility (in a cycle)

Intersection flexibility (in a cycle), coordinated operation – variation of the duration of the green signal according to the established limits, depending on the traffic flows, i.e. i.e. the duration of the green signal varies in each signal group, depending on the number of cars detected by traffic sensors and the occupancy of the detection zone. The signal program has a fixed cycle time at which the green signal must turn on for each direction. With a constant cycle time, the intersections are coordinated with each other (intersections have the same total cycle time) and thus a green wave is created between the intersections.

Full flexibility of the intersection

Full flexibility of the intersection (no cycle time), uncoordinated operation – the duration of the green signal directly depends on the traffic flows at the intersection. There are defined minimum and maximum time durations for each phase, and the cycle time is irrelevant and variable. Such a control method is applied at intersections far away from other intersections regulated by traffic lights, because such a control method increases the throughput of the intersection, but it is not possible to coordinate the intersection with other nearby ones and it is not possible to connect to the green wave.


MOTION (Method of the optimization of the Traffic Signals In Online Controlled Networks) is a real-time traffic optimization method. After receiving data on traffic flows from traffic sensors, the Traffic Control Center server calculates the most optimal signal program and phase times for each direction of the intersection. The server also determines the optimal cycle time and green wave parameters. Everything happens automatically every 6 minutes. This method is applied in about 120 city intersections. This method allows for a more efficient and prompt response to sudden changes in traffic flows, the beginning and end of the peak transport year. In the given picture, the signal program of the intersection is generated by MOTION.