A couple of blocks of Broad Street were closed to cars before dawn, as a demolition crew prepared to finish leveling a 10-story building to make way for the Convention Center expansion.

But around rush hour, traffic in the area was surprisingly light.

People got the word and stayed away, speculated the traffic officer at Broad and Arch.

Or maybe they got a headstart on the holiday weekend, said a cop at Broad and Vine - after chewing out a motorist for honking rudely.

Before the wrecking ball could swing, however, a street lamp and a traffic light had to be removed.

One hardhat worked on bolts fastening the lamp pole to the sidewalk, as a worker at a truck hoisted the hook that would pluck the pole away for storage.

A third man was tying off wires pulled out from the base of the traffic light.

The road, which typically handles about 30,000 cars on weekdays, will stay closed between Race Street and City Hall until May 31, if all goes well.

The Broad Street subway is still running, but SEPTA had to detour bus Routes 27 and C. (For details go to www.septa.org.)

In front of the stately Pennsylvania Academy of the Fine Arts were six big orange trailers, waiting to be filled with wreckage and hauled away.

Pedestrians were able to walk on the west side of Broad, though, inside a tunnel of board-topped scaffolding between the trailers and the academy.

The wrecking ball was expected to start swinging into the northwest corner around 10 a.m., said Richard Geppert, owner of Geppert Demolition, the company that will turn the vacant shell into metal scrap and clean fill.

The cornices with leaf motifs that rim the roof will join the rubble. "No, we don't have time," he said. "We gotta get the building down and the street back open."

The Dunkin' Donuts was still open at Broad and Arch, but customers can't park and deliveries have been disrupted, said manager Eric Zhang, 24.

Noise, dust and dirt add to the difficulties, he said.

"We control the dust," said Geppert. Lots of water is used, he said, pointing to pumps and fire hydrants.

Although Broad Street should reopen by June, a lot of rubble will still remain to be removed. A nearby old firehouse also has to go.

The work clearing the site will probably last into September, he said.

Contact staff writer Peter Mucha at 215-854-4342 or pmucha@phillynews.com.