Like many other growing cities, Winnipeg, Manitoba, sees once quiet neighborhood streets turning into busy thoroughfares that downgrade both property values and quality of life for the residents. When the traffic in a particular 1-mile stretch became too loud, the city concluded that a sound barrier wall was needed.
Of four materials selected for review--timber, concrete, steel, and glass fiber--timber was rejected on the basis of poor past performance in other cities, including high maintenance costs. On several counts the other three materials were considered equally good or highly competitive with one another, but concrete dominated in durability and resistance to vandalism.
The city decided that the wall should have an exposed aggregate finish on the residential side and a rough, vertical fin treatment on the traffic side. The panels themselves ranged in height from 7 to 14 feet, with a 6-inch recessed band near the top and bottom of each. Specified concrete strength was 4350 psi, with 3/4-inch maximum size aggregate that must be certified by the city. All reinforcing steel had to be epoxy coated. To meet the city's requirements the general contractor decided to use cast-in-place drilled piers topped by cast-in-place H-shaped columns with tilt-up panels that would slide down into place between the legs of the H.