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Traffic sensors
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Traffic sensors detect (count) traffic participants moving at intersections regulated by traffic lights or pedestrian crossings. They are necessary to ensure the adaptive operation of intersections so that traffic flows are regulated as efficiently as possible (to ensure the highest possible traffic flow capacity and reduce the time road users spend waiting at intersections). Traffic sensors are also needed to count traffic flows (collect statistics). All data obtained from the sensors is stored on a server and used for traffic flow analysis, traffic management planning, and optimization.
In Vilnius, we can distinguish three types of traffic sensors according to their purpose:
Traffic sensors (there are three types: induction loops, image and infrared sensors), pedestrian and cyclist sensors (infrared sensors) and pedestrian and cyclist buttons.
Image sensors
Vaizdo jutikliai veikia vaizdo atpažinimo principu.
Image sensor — an image camera that is configured using special software: a virtual zone (part of the street area) is set on the virtual street surface, the purpose of which is to recognize a vehicle.
When a vehicle passes through this zone, it is recorded (counted). The programming also specifies the direction of travel in which vehicles are to be detected (recorded). When programming image sensors, other factors must also be taken into account, such as: sensor sensitivity, position, viewing angle, distance to the roadway, and width of the lanes to be detected. Proper maintenance of image sensors and software updates reduce the margin of error in traffic flow counting.
Infrared sensor
The principle of operation of an infrared sensor is to detect traffic participants by measuring the infrared rays they emit, which are radiated from a specified detection zone (the sensor has as many zones as there are lanes for which it performs traffic flow calculations).
When recording traffic participants, slow changes in road surface temperature caused by changing weather conditions are ignored. Sensors that operate on the principle of infrared radiation (thermal imaging) are used to count cars, motorcycles, pedestrians, and cyclists.
Induction loops
Induction loops operate on the principle of electromagnetic detection: a passing car generates an electromagnetic pulse via an induction sensor embedded in the road surface, which is processed by the intersection controller and counted as a unit of traffic flow. The processed data is sent to the Traffic Management Center server.
Pedestrian and cyclist buttons
Pedestrian and cyclist buttons in Vilnius are sensor-activated, i.e., you just need to touch the button with your palm and the word „Laukite“ will light up on the upper part of the button.
Pedestrian buttons adapted for the visually impaired are installed at newly designed or reconstructed intersections and pedestrian crossings. They have a raised directional arrow on the button body and an additional audible signal function when the traffic light is red. If a sensor button adapted for the visually impaired is installed, it must have a button press confirmation function (sound signal or vibration). It does not matter how many times you press the pedestrian or cyclist button. One press is enough for the intersection controller to respond to your request. The number of presses does not affect when the green traffic light for pedestrians or cyclists turns on.
After pressing the button, the waiting time for a green traffic light signal varies at different intersections: if there is one or more intersections near the intersection (pedestrian crossing) that you are trying to cross or pass by bicycle, the operating modes between the nearby intersections will be synchronized and traffic flow through the nearby intersections will be coordinated. This traffic control method is called partial intersection adaptability. Therefore, after pressing the button, pedestrians or cyclists will only be allowed to cross the street at a specific, predetermined time. With fully adaptive intersection or pedestrian crossing control, the waiting time for pedestrians or cyclists is significantly reduced and the green signal can turn on almost immediately after pressing the button. This method of traffic control is possible at individual intersections or pedestrian crossings where the operating modes of traffic lights are not synchronized with each other.
Important: if there are pedestrian or bicycle buttons at a traffic light-controlled intersection or pedestrian crossing, they are operational and necessary for proper traffic control – be sure to press them if you want the green light to come on. If you do not press the button, depending on the traffic control at the traffic light, the green light may not turn on at all, or the wait for it may be twice as long, or the green light for pedestrians to cross the street may be shortened, and there is a risk that you will not be able to cross the street during the phase.
