SURFACE PROFILING APPARATUS AND METHOD

SURFACE PROFILING APPARATUS AND METHOD
FIELD OF THE INVENTION
This invention relates to an apparatus and method for measuring the profile of a surface, such as an airport runway, highway, raceway, parkade, bridge deck or any other surface requiring determination of roughness or smoothness.
BACKGROUND OF THE INVENTION
Manually operated rolling profiler instruments are emerging into the field of commercial profiling as a viable economic alternative to the cumbersome and labour intensive, as well as slow, rod and level method of survey, including straightedge surveys.
Foremost, profiling of runways, highways, raceways, parkades and bridge decks is required to monitor construction of these structures for conformance with design and traffic safety specifications. Surface profiling of runways and highways is necessary at regular seasonal intervals to determine the roughness value as a measure of pavement deterioration for maintenance purposes.
Previous methods of surface profiling have embodied inherent problems, such as that they are time consuming, cumbersome to operate and susceptible to acceleration and deceleration.
It is an object of the present invention to provide a method and apparatus for relatively easy, quick and accurate measurement of a surface profile, from which roughness or smoothness index values can be computed.
SUMMARY OF THE INVENTION
According to the invention there is provided a surface profiling apparatus having a forward support wheel, an intermediate support wheel and a rearward support wheel for travelling along a surface the profile of which is to be measured, said wheels being spaced apart at predetermined distances longitudinally of the direction of travel for travel along substantially the same line along said surface, and further comprising a forward frame member supported by said forward and intermediate support wheels; a rearward frame member supported by said intermediate and rearward support wheels, the forward and rearward frame members being pivotally connected together about the rotation axis of said intermediate support wheel; angle measuring means for measuring the relative orientation of said forward and rearward frame members with respect to the rotation axis of the intermediate support wheel; and inclination measuring means for referencing either of the forward and rearward frame members to a reference position which is independent of said forward and rearward frame members.
Also according to the invention, in a method of measuring the profile of a surface wherein a surface profiling apparatus having a forward support wheel, an intermediate support wheel and a rearward support wheel is moved along the surface, the wheels being spaced apart at predetermined distances longitudinally of the direction of travel for travel along substantially the same line, with a forward frame member being supported by the forward and intermediate support wheels and a rearward frame member being supported by the intermediate and rearward support wheels, the forward and rearward frame members being pivotally connected together about the rotation axis of the intermediate support wheel; the steps of measuring the relative orientation of the forward and rearward frame members with respect to the rotation axis of the intermediate support wheel to obtain an orientation value; referencing either of the forward and rearward frame members to a reference position which is independent of the forward and rearward frame members to obtain a reference value;