One of the biggest annoyances of cyclists is waiting in the rain. In some places in the Netherlands cyclists will face a green traffic light more often when it rains. With rain and a temperature below 10 degrees or in case of less densed traffic, cyclists will have a green traffic light two or three times instead of once.
The sensor measures whether it rains or snows. Precipitation in the sensor changes the cycle of the traffic light so the light turns green for cyclists more often.
The current trail will last half a year. If the test succeeds, then more bicycle-friendly traffic light will follow.