Sharraxaadda

For over years this light by Siemens has always had a sensor for ongoing traffic. It use to remain green unless someone is trying to turn into the driveway for Siemens. However, late at night this light now turns red when there is no one on the road to turn into Siemens or coming from this private drive. This is an inconvenience especially when there are 0 cars on the road late at night. I think the sensor is broken. Why is this light now turning red when there is no one there to set the sensor off?