NON-CONTACT, NON-DESTRUCTIVE PAVEMENT PROFILE, TEXTURE AND DEFLECTION MEASUREMENTS
Abstract
A non-contact, non-destructive method is described that allows the user to measure pavement texture and loaded and unloaded profiles from a moving vehicle. The device uses laser distance measuring gages. The gages are arranged such that their readings can be interpreted to give the loaded and unloaded pavement profiles and a measure of its texture. Four gages are mounted on a rigid beam that, in turn, is mounted on the side of a load vehicle. The gages read the distance to the pavement. Three of the gages are located outside the range of influence of the load wheel, and hence the pavement below these gages is undeflected. One of the gages is adjacent to the load wheel to measure the induced deflection. An algorithm is presented that relates all measurements to a common datum. The three gages yield readings that are interpreted to give the profile (do the surveying). The gages make so many readings and so quickly, that the standard deviation of the readings, taken over a short time period, gives a measure of the texture. A prototype device was constructed and tested. The results were: (1) Pavement profiles were calculated using the new system. These compare favorably, though not completely, with the transit surveys. (2) Standard deviations were recorded. These readings were taken over concrete, asphalt and porous friction surface pavements. Differences were noted between the textures of concrete (smooth) and asphalt (rough) pavements. No correlation between this measure and standard measures was made. (3) The deflections caused by prototype loads were measured and recorded. This was done from the load vehicle, while the vehicle was moving across a pavement at the U. S. Army Corps of Engineers Waterways Experiment Station, in Vicksburg, Mississippi. The scheme for obtaining the resulting deflections is descibed in detail. An algorithm for accomodating the misalignment of the laser gages on the rigid beam is also presented. Suggestions are offered for improving the system.
Degree
Ph.D.
Subject Area
Civil engineering
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