Various types of strain gauges, pressure cells, deflection, temperature, andvehicle transverse position indicators have been used to instrument flexible pavements. Each sensor has its own design, operation, and installation techniques in addition to large variability in unit cost. The state of the art of these instruments is described in terms of their designs, performance, installation, and availability. Various types of strain gauges for the bonded and unbonded pavement layers are discussed. Different types of pressure cells are described, and some recommendations are given for the selection of the type and dimensions of these gauges. The principles of the acceleration, velocity, and deflection measuringdevices are discussed. Temperature sensors are also described and the basic features of each element are presented. Finally, the various types of the transverse position indicators are discussed. This paper appears in transportation research record no. 1260, Measurement of pavement surface condition 1990.
Samenvatting