Traffic control systems hardware

In the past ten years the technology of traffic control has experienced extensive change. Equipment which was once familiar to traffic engineers and maintenance personnel has been supplanted by the new breed of devices using solid-state digital circuitry, sophisticated multiplexing, and microprocessor logic. The changes in operational capability and technical performance of systems brought about by these advances have been widely acknowledged. However, the impact upon the user is only beginning to be realized, as traffic engineers learn to cope with such considerations as operator training, maintenance, reliability, updating, and expansion. The current developments in traffic control systems hardware and the experience that is starting to be collected with respect to their installation and use are discussed. Technical and nontechnical factors are discussed and future directions are predicted.