You hear it sometimes before you see it — the pang pang pang of rhythmic hammering, the clang of dropped metal, the smock of dropped wood. When you turn the corner you see the familiar sight: a crew of Central Americans or Africans humping pipes, girders, planks, and plywood from a truck and throwing them up into the air. Another scaffold is going up.
The technical name for these urban portes cochères is sidewalk sheds, and the city requires them whenever there is serious construction, demolition, or ordinary repair. Any building, from 19th-century brick or brownstone runts, to gargoyled beaux-arts matrons, to the white-brick slabs of Camelot, to the glass Rubik’s cubes of postmodernism’s nightmares, is liable to grow a ground-floor girdle. The basic design is everywhere the same. The verticals, or bridge legs, are thick metal pipes. Slimmer pipes, with pinched ends, are clamped alongside to form horizontal braces, or X-shaped cross braces. The business end — what prevents tools, workmen, or random cornices from toppling onto your head — is the deck. Metal beams clamped to the tops of the bridge legs run across the sidewalk, metal runners are laid at right angles over the beams, and a ribbed metal sheet surmounted by wooden planks is laid over the runners. Plywood parapets offer extra insurance against objects or people rolling into the street. The prevailing color scheme of plywood these days seems to be dark blue, though I can remember parapets of forest green.