A conveyor system, comprising: a plurality of work piece carriers, each presenting a machine readable and writable tag and being adapted for supporting at least one work piece during transportation; a distribution highway conveyor in the form of an endless conveyor adapted for transporting and circulating said work piece carriers; at least two operation unit conveyors (OUC1, OUC2, OUC3, OUC4), each in the form of an endless conveyor adapted for transporting said work piece carriers, wherein the operation unit conveyors (OUC1, OUC2, OUC3, OUC4) are arranged to receive a work piece carrier from an associated distribution highway (DHC1, DHC2), to move it to an operation station (OS1, OS2, OS3, OS4), and to return the work piece carrier to the distribution highway (DHC1, DHC2) after processing at the operation station (OS1, OS2, OS3, OS4); characterised in that the conveyor system comprises: at least a second distribution highway conveyor in the form of an endless conveyor adapted for transporting and circulating said work piece carriers; at least one flow balancing conveyor in the form of an endless conveyor adapted for transporting said work piece carriers, wherein the distribution highway conveyors (DHC1, DHC2) are interconnected via the flow balancing conveyor, such that said work piece carriers can pass from one of the distribution highway conveyors (DHC1, DHC2) via the flow balancing conveyor to the other distribution highway conveyor (DHC2, DHC1); wherein a respective tag writer device is configured to derive a next operation address and to write said address to the tag of the work piece carrier after the processing at the operation station (OS1, OS2, OS3, OS4); and wherein autonomous switch control devices (11a, 11b, 11c, 11d; 13a, 13b) are arranged at each intersection between conveyors to control the flow of the work piece carriers at the respective intersection. a plurality of work piece carriers, each presenting a machine readable and writable tag and being adapted for supporting at least one work piece during transportation; a distribution highway conveyor in the form of an endless conveyor adapted for transporting and circulating said work piece carriers; at least two operation unit conveyors (OUC1, OUC2, OUC3, OUC4), each in the form of an endless conveyor adapted for transporting said work piece carriers, wherein the operation unit conveyors (OUC1, OUC2, OUC3, OUC4) are arranged to receive a work piece carrier from an associated distribution highway (DHC1, DHC2), to move it to an operation station (OS1, OS2, OS3, OS4), and to return the work piece carrier to the distribution highway (DHC1, DHC2) after processing at the operation station (OS1, OS2, OS3, OS4); characterised in that the conveyor system comprises: at least a second distribution highway conveyor in the form of an endless conveyor adapted for transporting and circulating said work piece carriers; at least one flow balancing conveyor in the form of an endless conveyor adapted for transporting said work piece carriers, wherein the distribution highway conveyors (DHC1, DHC2) are interconnected via the flow balancing conveyor, such that said work piece carriers can pass from one of the distribution highway conveyors (DHC1, DHC2) via the flow balancing conveyor to the other distribution highway conveyor (DHC2, DHC1); wherein a respective tag writer device is configured to derive a next operation address and to write said address to the tag of the work piece carrier after the processing at the operation station (OS1, OS2, OS3, OS4); and wherein autonomous switch control devices (11a, 11b, 11c, 11d; 13a, 13b) are arranged at each intersection between conveyors to control the flow of the work piece carriers at the respective intersection.