As part of an operational test assessing the effect of tire pressure on aggregate roadway deterioration, an instrument was developed to monitor deformations of the surface and subgrade at selected cross sections. This liquid level gauge measured elevation differences with a pressure transducer and recorded field data for processing on a personal computer. Data from this device were plotted to show cross sections of the roadway structure with a precision of 3 mm (0.1 in) for subgrade readings, and 8 mm (0.3 in) for surface readings. Surface and subgrade deformations were evaluated at weekly intervals and before and after maintenance activities. Rut development was traced, and contributions of subgrade and surface deformations were isolated. The instrument was portable, compact, and not affected by field or environmental conditions.
Samenvatting