LAS VEGAS: With less than 48 hours until one of this city's favorite but rarest of spectacles, the principal players stood around a long table on Sunday morning readying their props and showing no traces of stage fright.

Well, maybe just a little, considering that the Loizeaux clan still had to finish threading several hundred eight-inch sticks of dynamite with yellow ignition rope and race through the stripped-down carcass of the New Frontier Hotel-Casino stuffing the explosives into the correct pillars.

"We've got a lot to do," said Mark Loizeaux, 58, whose wife, son, two daughters and a daughter's boyfriend worked beside him. "But we'll get it done. We always do."

Thousands of onlookers are expected to crowd along the Las Vegas Strip at 2 a.m. Tuesday to watch as the Loizeauxes set off a chain reaction of explosions that will force a storied but tired property to collapse upon itself. A fireworks show is planned, too, but the main attraction is clearly the destruction of the New Frontier to make way for a splashier edifice.

The Loizeauxes are the first family of a decidedly distinct business that started with Mr. Loizeaux's late father, Jack Loizeaux, who as a Baltimore forestry worker realized in the late 1940s that dynamite was the easiest and fastest way to remove the roots of trees that had died from Dutch elm disease. That discovery led to a full-time job blowing up tree roots until others started asking him to knock down man-made structures, too. He went on to blast coal tipples, low bridges and eventually buildings.

As business picked up, Jack Loizeaux founded Controlled Demolition Inc.; his wife was the first to use the term "implosion" as a softer way to describe using explosives to make a building crumble of its own weight. Jack Loizeaux's two sons later took over his business, and now several of his grandchildren are on the job, too. The staff of Controlled Demolition, a multimillion-dollar business, includes about a dozen people, half of whom are family members who also share a 45-acre estate in Baltimore County.

"One of the reasons why this is a family business is anybody in this building is capable of taking all our lives with one mistake at any point in time," said Mark Loizeaux, who lost much of his hearing and was badly banged up in 1973 when an unspent piece of dynamite exploded as he worked in a debris pile after an implosion. "There needs to be a high level of trust."

After the New Frontier, these Grim Reapers of architecture are scheduled to jet off to Bal Harbour, Fla., to demolish two shuttered towers of a Sheraton. By year's end they are to take out a grain elevator in Philadelphia, a 10-foot-tall below-ground structure at the Escondida Copper Mine in Chile and the Susquehanna River Bridge near Harrisburg, Pa., which is being replaced. Other notable projects have included the Kingdome in Seattle and the remains of the Alfred P. Murrah Federal Building in Oklahoma City after the 1995 bombing.

"It's always been normal because I grew up in it, but of course your friends always think it's extremely odd," said Devon Loizeaux, a daughter. "I get to travel the world. I'm 26 and I've been to 11 different countries; we might be going to Korea soon."

All that is fun and challenging, Mr. Loizeaux said, but the Vegas jobs draw the most attention because the structures being destroyed are not especially old and are always replaced by something more grand.

"Only in Vegas do structures this young come down, because time is money here and money is what Vegas is all about," Mr. Loizeaux said. "The purveyors here understand what it takes; they know how to sacrifice a structure if they can replace it with something that's going to be more beneficial, a bigger draw, a little glitzier, a little more glam involved."

This time, the New Frontier, which opened as the Hotel Last Frontier in 1942 and was the second resort on what would become the Strip, is to be replaced by the Plaza, a $2 billion hotel-casino from the Israeli owners of the Plaza Hotel in New York City.

The New Frontier, whose name, theme and owner had changed several times, was notable as the first spot Elvis Presley played in Las Vegas in 1956 and as having been once owned by Howard Hughes. But more recently it was known as the site of a six-year strike in the 1990s by culinary workers, and the hotel had deteriorated to the point that the casino developer Steve Wynn last year called it "the single biggest toilet in Las Vegas."

The remarkable precision of the Loizeauxes' work - the 32-story Stardust Hotel-Casino collapsed in less than 10 seconds in March - keeps them atop the field, said Alan Feldman, spokesman for MGM Mirage, which hired the Loizeauxes most recently to demolish the Boardwalk Hotel-Casino on the Strip.