Not all the towers along a transmission line are identical. Look closely at a tower where the line makes a sharp turn and you will likely find it is wider and beefier than other towers along the route. The added strength and weight are needed to resist the unbalanced pull of the conductors, which might overturn an ordinary tower. These special towers are called deviation or angle towers.
The transmission-line tower everybody knows is an Erector Set latticework of steel girders and diagonal braces. The techniques for designing and building these towers are the same ones used in constructing steel bridge trusses or crane booms. The individual pieces can be made cheaply from rolled steel and then bolted together on the site. This last point is more important than it might seem: transporting a fully assembled tower 100 feet tall is an awkward and expensive business.
It is a concept based not on the classification of various physical features of architecture and urban design but on the problem-solving process itself. We have seen that the final outcome of a design process is strongly determined by at least three aspects of that process:
the subject matter of the organizing principles which are adopted,
the manner in which these principles are interpreted and reinterpreted in the context of the problem at hand, and
the sequent of applying such organizing principles.
Consistency in style among the output of designers can thus be understood as a habitual way of doing things, of solving problems.