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.
Walk Appeal promises to be a major new tool for understanding and building walkable places, and it explains several things that were heretofore either contradictory or mysterious. It begins with the assertion that the quarter-mile radius (or 5-minute walk,) which has been held up for a century as the distance Americans will walk before driving, is actually a myth.
Both images below are at the same scale, and the yellow dashed line is a quarter-mile radius. On the left is a power center. As we all know, if you're at Best Buy and need to pick something up at Old Navy, there's no way you're walking from one store to another. Instead, you get in your car and drive as close as possible to the Old Navy front door. You'll even wait for a parking space to open up instead of driving to an open space just a few spaces away… not because you're lazy, but because it's such a terrible walking experience.
The image on the right is Rome. The circles are centered on the Piazza del Popolo (North is to the left) and the Green radius goes through the Vittorio Emanuele on the right. People regularly walk that far and then keep on walking without ever thinking of driving.