Recent developments in electronic systems for road tunnels and bridges

At a crossing (tunnel, bridge or combination thereof), there may be any type of traffic management requirement from none to a system of tidal flow and tolls. With the greater traffic loading of many crossings and their increased use in motorway networks, greater reliance is placed on the use of electronic systems, which help to increase traffic flow, reduce staffing costs and accidents and provide better records for maintenance and information for operation. Major systems currently in use include those for traffic control (on approaches and within the crossing), traffic surveillance (by CCTV inductive loops, etc.), plant monitoring and control, communications (by radio and telephone), and toll collection. This paper reviews the major developments of recent years, with reference to appropriate examples.<>