Population growth of cities and towns in recent years has caused residential and commercial development of large areas of land around such cities and towns. Increased densities and speeds of traffic have thus been necessitated for travel to and within such areas, requiring many new roadways or roadway improvements (e.g. additional roadway lanes) while increased population density and land values have required utilization of land which often abuts major traffic thoroughfares where relatively high levels of noise are present. Such noise will often be communicated to nearby properties where the noise may interfere with desired uses of such property.
In recent years, walls have been constructed to function as acoustic baffles or barriers in an effort to reduce noise levels at locations adjacent to roadways where commercial, high density and/or high speed traffic is present. Such walls must be sturdily built of materials which are not easily damaged by weather conditions such as high winds or by possible impact from vehicles. The walls must also be relatively tall (e.g. eight feet to thirty feet or more) and must be securely anchored, requiring support posts to be of extreme length, generally twenty-five feet greater than the wall height or fastened to reinforced concrete caissons extending to a twenty-five foot or greater depth in the ground. Such a fastening has generally been accomplished by having large bolts embedded in or attached to the caisson using a flange and a complementary flange affixed to the post which can thus be affixed to the caisson below grade level and the connection then encapsulated with concrete to fill the remainder of the post hole above the caisson. Both the provision of a flange of sufficient robustness and the attachment of the post to the caisson contribute substantially to the overall cost of the wall system. Moreover, such structures and operations also required the posts to be installed several days prior to the installation of the wall sections (usually provided as panels of a standard height which are then essentially stacked edge-to-edge in grooves in the posts) in order for the concrete fill to cure adequately to carry loads imposed by the wall segments and their installation. Thus the installation of posts and installation of wall panel segments in separate operations increases the duration of construction time, the amount, types and movement of machinery required and the amount of labor involved, further contributing to cost of such walls. Further, such large structures may be required for both sides of substantial lengths of roadway and can thus add significantly to costs of roadway construction or improvement.
These factors favor construction of such barriers from large standardized wall panels of pre-cast concrete which are supported in grooves of some construction such as wide flanged or H-shaped steel beams which are anchored securely in the ground. However, for aesthetic as well as maintenance cost reasons, cast concrete posts having opposing grooves to receive the wall segments have been favored in recent years even though difficulties are presented in providing such opposed grooves of sufficient strength and accuracy.
In any case, somewhat different machinery has been required to anchor the posts in the ground with highly accurate spacing to receive ends of wall panels and to assemble the wall panels to them in separate operations. Further, if damage or settling occurs, the posts could shift and possibly allow the wall panels to become detached therefrom, particularly where wall panels of standardized size are stacked edge-to-edge, as alluded to above. Moreover, when a wall is built on terrain which is other than flat, such as where a grade is present, the bottom-most wall panels will generally reach the ground at only one corner, causing unbalanced and uncontrolled stresses in the wall which are transferred to the posts; aggravating any shifting which may occur and possibly causing wall failure.