‘Giant Cranes’ Stuck in Low Gear

There is a whole genre of children’s books and videos devoted to explaining how various machines work, especially trucks, airplanes and trains. They are designed to tap into the natural sense of wonder that kids have about the world.

Recognizing that many people retain this curiosity as adults, the Discovery Channel frequently offers programs that give an insider’s view of things most of us take for granted. There are three of them on tonight: repeats of “Making of a Coaster” at 8 and “World’s Largest Amusement Park” at 9, followed at 10 by the premiere of “Giant Cranes,” a documentary about the huge devices that help construct buildings, unload cargo ships and, as we’ve been reminded all too recently, clear debris from disaster sites.

“They are elegant marvels of human engineering,” narrator Hector Elizondo tells us at the outset, “gossamer towers of steel and wire.”

Unfortunately, the program doesn’t live up to that eloquent description. .

The filmmakers apparently didn’t want to do any heavy lifting themselves. While we learn the names of the crane parts, we aren’t told how they work. We see footage of two cranes collapsing to underscore the point that working on them can be dangerous, but we never find out what caused the mishaps. We meet a woman who is training to become a crane operator, but learn nothing about what drew her to the male-dominated profession or what her experiences in it have been.

The most interesting segment comes at the end, when we see that cranes also are being used to lift scientists to the tops of forests, where they can study parts of the trees and varied forms of wildlife that previously were out of reach.

Too bad “Cranes” never soars like those scientists do.