one of the earliest wim systems, still used in a minority of installations, uses an instrumented existing bridge as the weighing platform. bending plates span a void cut into the pavement and use the flexure as the wheel passes over as a measure of weight. load cells use strain sensors in the corner supports of a large platform embedded in the road. the majority of systems today are strip sensors - pressure sensitive materials installed in a 2 to 3 cm groove cut into the road pavement. in strip sensors, various sensing materials are used, including piezo-polymer, piezo-ceramic, capacitive and piezo-quartz. many of these sensing systems are temperature-dependent and algorithms are used to correct for this.