The steepest grade on U.S. main-line track is at the small town of Saluda, on a Norfolk Southern route between Spartanburg, South Carolina, and Asheville, North Carolina. The grade goes on for three miles at a slope of 4 or 5 percent. Trains have not been running on the line since 2001, but the tracks are still maintained.
For those who've never experienced a sunrise in the rural Midwest, it's roughly as soft and romantic as someone's abruptly hitting the lights in a dark room. This is because the land is so flat that there is nothing to impede or gradualize the sun's appearance. It's just all of a sudden there.
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.