Vienna gets pedestrian traffic lights based on cameras and without buttons
In Vienna, from the end of 2020, pedestrian traffic lights without push buttons will be installed at certain locations. Cameras register when pedestrians want to cross, which the traffic light is adjusted to. The lights work based on research from the Austrian Technical University of Graz.
Researchers at the Computer Graphics and Vision Institute at the Technical University of Graz have said they have developed a system over the past three years to make the push buttons for crossing a street superfluous. The system is camera-based and recognizes the intention of pedestrians to cross the street. Then the light will automatically turn green. Algorithms have been developed for this recognition based on worldwide motion models and recorded data from previous trials.
According to one of the researchers, this system also leads to a better traffic flow. This is because the duration of the green light for pedestrians can be extended when there is a large group of people waiting to cross. In addition, the cameras register when waiting pedestrians lose their patience and decide to continue to another crossing. The light does not turn green, so that motorized traffic does not have to wait unnecessarily. At the push of a button, the traffic light for pedestrians would have turned green anyway.
The basis of the system is formed by a single camera. It is mounted on the traffic light for pedestrians at the crossing. According to one of the researchers, existing systems have a field of view of two by three meters, but their system’s cameras can recognize pedestrians in a larger area of eight by five meters. The system needs a second to estimate the intention of crossing. After two seconds, that estimate becomes reliable, says one of the researchers. This desire to cross is then passed on to the pedestrian traffic light control system, where the push button function is transferred, as it were. This means that it is automatically decided whether the lights should change color. According to the scientists, the system is able to recognize a crossing intention three to four seconds faster compared to the traditional situation of a push button.
Researcher Horst Possegger reports that this sounds relatively simple, but that it was preceded by two years of intensive research. According to him, this is related to the complexity of the technical requirements. For example, the required hardware had to be large enough to form a powerful local computer, but at the same time small enough to fit in the switch box of a traffic light. In addition, there had to be room for a monitoring system that can immediately detect errors. The system must also function in difficult weather conditions, and can cope with fluctuations in the mains voltage.
Possegger states that privacy has also been considered. Even though the cameras can detect pedestrians and this provides privacy-sensitive data, these images are only analyzed locally and are not forwarded from the camera or computer of the relevant traffic light. According to the researchers, the system also works exclusively with geometric information.