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.
In my opinion, what makes a designer competent is precisely their ability to credibly justify their conclusions. If you can’t do this as a designer—no matter how successful your results are—then neither I nor anybody else can tell if you aren’t just picking things at random.
What I am proposing, then, is no less than to make a designer’s entire line of reasoning a matter of permanent record. On the surface is the familiar set of prescriptions, components, examples and tutorials, like you would expect out of any such artifact. Attached to every element, though, is a little button that says You click it, and it tells you. The proximate explanation will probably not be very satisfying, so you click on the next until you get to the end, at which point you are either satisfied with the explanation, or you aren’t.