ABSTRACT
This chapter examines the basic concepts of formal composition, meaning how the plan of the urban object is composed of geometrical elements, in the American town planning tradition. It argues that there is a finite set of concepts combined in regular grid planning, principally rectangularity of blocks and parallel/perpendicular streets based on the right angle, using notional plans and historical examples. A right angle connection between two streets where only three directions are feasible in terms of the layout itself is a three-way intersection. In the case of three-way intersections, one street terminates where another street continues. Like two-way intersections, a three-way intersection can also define the perimeter of the layout due to being the termination point of a street at the edge. The chapter discusses the different types of regular grid patterns in American settlements. Topological graphs underlie every representation as the basis for quantitative measures of the configurational network at the urban level.
