A deflectometer is a specialist device used to determine the stiffness of a road pavement. The most common form of the apparatus is the well-known Falling Weight Deflectometer (FWD) but, in recent years, new ‘traffic speed’ deflectometers (TSD’s) are being developed. The Danish company, Greenwood Engineering are the main developers of TSD’s in the world today and have supplied vehicles to the UK, Poland and Italy where they are currently being trialed.
The concept of ‘inspecting’ bridges for damage using a vehicle travelling at full highway speed has emerged in the past decade. While it has shown promise in simulations by UCD and in scaled laboratory models, it has yet to be proven in the field. TRUSS will further develop and test this promising technology that may allow the monitoring of safety of many bridges by simply driving the TSD over them.
Bridges vibrate in response to passing vehicles and the nature of this vibration changes when the bridge is damaged. The bridge vibration excites the TSD vehicle and it is this vehicle vibration that will be used as an indicator of bridge damage. A measurement taken directly on the bridge is clearly a more direct approach than using a measurement taken on a vehicle to infer information about the bridge.