Acropolis CraneA crane in ancient Athens, as depicted in Manolis Korres's "Pentelicon to the Parthenon." Enlarge this image.

The construction crane has seen many incarnations over the 2,500 years that men have employed the machines. Beasts of burden are no longer needed to power them. Winches and pulley systems became ever more elaborate. Steel replaced wood at the onset of the industrial revolution, allowing for ever greater loads to be lifted.

Despite the changes, however, the crane's form has remained as consistent as its function: lifting heavy loads without toppling over. And the massive structures have long caused a certain amount of consternation among the pedestrians they loomed over like the sword of Damocles.

In 1967, The Times editorialized, "Those arrogant cranes which bestride New York's streets like prehistoric beasts constructed of nuts and bolts are peril to pedestrian and motorists alike."

With Friday's fatal crane accident, the second in Manhattan in the past two months, New Yorkers renewed nervous glances skyward and, inevitably, some wondered why some technology seems to change so little. (The cranes at several construction sites are now being examined at several major construction sites in Manhattan, where work is likely to be delayed for days or weeks while safety concerns are addressed.)

In a city that is supposed to epitomize modernity as it constantly tears itself down and builds back up, the interplay of the constant and ever-evolving can be striking.

When a steam pipe burst near Grand Central Terminal last summer, many were surprised to learn that much of Manhattan is heated and cooled via a 105-mile underground network of pipes — many installed more than a century ago. While the explosion raised questions about the system's upkeep, it also became clear that steam was simply more efficient than many other, newer systems.

Likewise, the fundamental rope-and-pulley mechanism of the elevator, an invention that allowed for the construction of the skyscrapers that define this city, has changed very little since 1853, when Elisha Otis introduced the safety brake that prevented a cab's crashing to the ground if a rope breaks.

"With technological systems, some of them are pretty highly mature, and pretty highly evolved," explained William J. Mitchell, a professor of architecture and media arts and sciences at the Massachusetts Institute of Technology.

Like the automobile. "A lot of smart people have been working on it for years," Professor Mitchell noted, but changes have been incremental. Yet other technology, like computers and the Internet, are revolutionary and rapidly evolving.

"Obviously, different sort of technology systems work in more or less demanding circumstances," he said. "Cranes have to work in very confined spaces, have to carry heavy loads and are surrounded by people living their lives all the time."

Cranes Kill (Photo: Andrea Mohin/The New York Times) Enlarge this image.

When something goes wrong, it is not surprising that the costs can be high.

While the basic mechanism of cranes has remained the same, experts on city construction and admirers of the skyscraper are quick to note that that there have been some technological advances (and regulatory ones as well).

The Empire State building was built in 1931 using derrick cranes, which had to be hoisted up the building as construction went along, secured on each newly completed floor. The construction of the World Trade Center towers in the 1960s and 1970s marked the first time "kangaroo" or "jumping" cranes — like the ones in the recent accidents — were used in New York.

These cranes, which are self-assembling machines that are raised from the ground, are now the standard at construction sites across the city and, indeed, the world, including on the Burj Dubai in the United Arab Emirates, destined to be the tallest building in the world.

But Professor Mitchell, of M.I.T., said that the construction business does not lend itself to big breakthroughs, especially in the way it is practiced in New York.

"Construction sites are things that have been around for thousands of years," he said. "Construction is very strange compared to other industries. There are many small operators as opposed to big players."

Often, he noted, it is just a couple of guys riding around in a pickup truck. That kind of decentralization makes sweeping change unlikely.

Still, Professor Mitchell said that the advent of computer-assisted fabrication of materials and new tools that help the various parties involved in a construction product communicate are making possible things like the oddly shaped buildings associated with architects like Frank Gehry.

It is possible that the future could bring some amazing new advances in construction, like the swarms of tiny robots imagined by some advocates of nanotechnology. "There could be a day when high-rises are constructed using nanofactories," said Patrick Tucker, senior editor of The Futurist magazine. The nanofactories would "spin super strong building material, the way spiders build webs." And that, he said, "would eliminate the need for cranes."

But even in an age of rapid technological advances, some things don't change. To build a tall building, a hole needs to be dug and materials must be hoisted into the air.

Unless you're a termite. Professor Mitchell said he often uses the little creatures as a teaching tool. They have been involved in complicated construction projects since long before the first crane was ever erected. "They are able to construct fantastically sophisticated termite mounds from pellets of mud," he noted. "They are large, complex things, even having their own sophisticated climate control."

It is all done, he said, with no construction foreman and no architectural design.

David W. Dunlap contributed reporting.