A traffic signal system for congested trafficways has a plurality of stationary alarm light/sensor-reader combinations and mobile alarm light/sensor-reader combinations monitoring each other and monitory tags placed on individuals, machines, and hazards to provide real time alarms to not only pedestrians but also machine operators, who are potentially approaching harm's way, or have the better ability to avert potential harm. Different forms of alarms are provided to indicate different kinds of alarm conditions and to reduce complacency to alarms, and thus improve effectiveness.