In 1989, in the midst of a windstorm, Leslie Pluhar was driving across the Mackinac Bridge, which joins the Upper and Lower Peninsulas of the state of Michigan. Apparently concerned by the weather, she stopped her tiny Yugo on the bridge – a fatal mistake, for the car was caught by the gale and thrown 150 feet into the strait below.

Henry Petroski does not discuss Pluhar’s tragic death in his new book, “Pushing the Limits” (Alfred A. Knopf, 304 pages, $25), but he does help to explain it. The Mackinac was built with a rather unique feature. The designers feared that strong wind might set the bridge in motion, and so its span consists in large part of open steel grating that allows the air to pass harmlessly through. Unfortunately, this also creates an upward force on each car, which must be counteracted by a downward force – in other words, keep driving.

The unforeseen consequences of decisions made by the engineers of bridges, dams, and skyscrapers are the recurring theme in this volume of essays – a fitting follow-up, in that sense, to Mr. Petroski’s last book, “Why There Is No Perfect Design.” Many of the structures he writes about in this collection (all of the essays were originally published in the American Scientist) were the longest, tallest, or otherwise most extraordinary of their kind at the time of their construction. Most were extraordinary successes; a few were failures, some tragically so. Mr. Petroski lucidly explains the decisions of the engineers and generally defends them. Taken together, these essays are a sympathetic but clear-eyed celebration of those who imagine and build what has never before existed.

Bridges occupy most of Mr. Petroski’s attention in this volume. The Brooklyn, Mackinac, and Akashi Kaikyo Bridge near Kobe, Japan, were each the longest suspension bridge in the world at one time (the last still is), but their engineers faced far different challenges. John A. Roebling was attempting to suspend his bridge across a distance four times longer than any engineer had managed before; to do so, he constructed two towers that were larger than any building in New York at the time. The Akashi Kaikyo bridge, opened in 1998, spans more than two miles – making it more than eight times as long as the Brooklyn. The builders were less concerned with length than with earthquakes (an enormous one struck during construction and caused some resettling, but the structure survived nicely).

As Mr. Petroski takes us through the design of even relatively more modest projects such as the Woodrow Wilson Bridge across the Potomac, the Millennium footbridge across the Thames, and the Pont De Normandie that connects Honfleur and Le Havre in France, he repeatedly underscores one point: Any bridge or skyscraper is in fact a unique undertaking, due to differences in terrain, technology, and resources.

Some of the book’s most interesting portions come when Mr. Petroski turns his attention to what went wrong in an ill-fated structure. His tale of the enormous bonfire constructed annually by students at Texas A&M, which collapsed in 1999, killing 12, is a textbook study in what Mr. Petroski calls “tradition carried forward without conservatism.”

A series of seemingly harmless design habits – in this case things like the length of logs used for the fire and the way in which they were wedged together to create a 55-foot pile that would then be burned – can together eventually lead to catastrophe. “In this respect,” Mr. Petroski concludes, the collapse “repeated the pattern of a great number of colossal failures that have plagued amateur and professional builders throughout history.” Every structure is, essentially, a brand new invention, he preaches, and must be treated as such.

After contemplating catastrophes – there is a notable essay on the collapse of the World Trade Center – it is a pleasure to turn to Mr. Petroski’s final two chapters cataloging some exceedingly ambitious projects dreamed of by past generations of engineers and some still mooted today. The Three Gorges Dam? Almost.A tunnel underneath the English Channel? Amazingly, yes. A bridge across the Strait of Gibraltar? Keep dreaming.

And then there is the Brooklyn Bridge, that minor miracle, which somehow makes the pedestrian “feel not small and insignificant but part of a larger humanity that could erect this grand edifice with little more than muscle and steam power.” It is a measure of Mr. Petroski’s skill and sensibility that his essays about structures made of steel and stone so frequently provide a sense of that larger humanity, as well.