This paper describes a complete prototype system that uses Floating Car Data (FCD) for both automatic and manual detection of queues in traffic. The system is developed under EU’s Tempo program. The systems consists of small hardware units placed in mobile traffic report units (we use taxis) and backstage databases that collect all data send from the report units. The communication between the taxis and the databases is based on a very compact wireless communication protocol. A one month field test using ten taxis shows that the system is operational and that communication costs are very low (33 euro per taxi per year).