Measuring Time Dependent Pavement Surface Deflection Profiles Under Rolling Vehicles Using a Portable System

Several of the approaches proposed would involve arrays of vertical-sensing sensors plus horizontal-sensing sensors supported by a 4-meter long lightweight beam. End supports could extend out from the roadside, or consist of longitudinal extenders. Thevertical-sensing sensors would sense road profile and pavement deflection under load. They could be either contact sensors (linear variable differential transformers) or optical distance sensors. The horizontal-sensing sensors would be low-costultrasonic sensors, and would be aimed toward the vehicle's tires. They would record the actual lateral position of the tires during the test. By clearly indicating whether there is a tire next to any of these horizontal-sensing sensors, they would alsorecord the longitudinal position of the vehicle wheels at any instant in time. Representing a different approach, a scanning laser option would also be considered. The Phase I development would center on survey of different technologies and choosing thebest candidate design. The Phase I Option would include evaluation of candidate sensors under laboratory conditions and subsequently, completing a final hardware design.Such a system would provide the Army with a portable method for assessing loadcarrying capacity of roads in widely different world locations, before driving military convoys over them. This would help minimize potential friction with the governments involved. Use in airport runway testing may also be anticipated. In assessing theload carrying capacity of roads in the USA, in view of the low estimated cost per system, interest by county governments as well as state departments of transportation is anticipated.