A feel for the road

Over the years the use of traffic flow sensors has expanded from basic measurements from the signal, through to software-supported advanced applications including sophisticated computational systems, traffic management systems and advanced traveller information systems. Over-roadway sensors include the video image processor, infra-red and radar; in-road sensors are point sensors, battery powered magnetometer sensors and inductive loop detectors (ILD). Most sensors are affected by weather, dirt, noise and positioning. With over-roadway sensors, light variations and vehicle/road contrast can be a problem; with in-road sensors, long installation times and poor pavement quality can create difficulties; signal-to-noise ratio is also a factor. ILDs are now being marketed with signal signature analysis and data processing. A new kind of solar powered sensor and integrated alarm has been recently been installed on some rural roads to warn off approaching animals such as deer. Looking to the future, it is likely that signal data processing technology is applied more and more to sensors. Multi-target, multi-sensor data fusion will be applied to vehicle detection. Vehicles themselves are likely to become interactive sensors with the introduction of Vehicle Infrastructure Integration.