The flat beds carrying blaze orange bad news were already moving into position this afternoon. Dutiful workers dragged road barriers as big as goal posts across Broad Street, the signs "Right Lane Closed Ahead" tilted ominously above their hard hats.

Full-page, politely apologetic warnings entitled "A Message from the Philadelphia Office of Emergency Management" flapped on the windshields of cars parked in the lot outside Hahnemann Hospital.

Patience, people. That's what you're going to need.

Patience and forebearance and an eye on the long-term benefits of an expanded Convention Center. Because starting at 5 a.m. tomorrow, for eight days, 24 hours per, a critical section of North Broad Street in the knotted epicenter of the city will be shut down to traffic.

The subway won't be affected, but above ground, northbound Broad Street will be closed between JFK Boulevard and Race Street and southbound between Race and Arch Streets. (SEPTA will use alternate routes for bus routes 27 and C, and the Broad Street Line NiteOwl. Details are available at www.septa.org.)

An estimated 30,000 cars drive up and down that stretch on weekdays, half as many on weekends and holidays.

That's a mess of diverted traffic, admits Joseph Resta, project manager of the Pennsylvania Convention Center, the man behind the plan causing this temporary misery.

Resta says he feels the city drivers' pain. And he expects, any minute now, to start getting the calls.

"I think it's understandable that the collective road rage of the city is going to be foisted upon us very shortly," he said today. "If I didn't have any involvement with the project, I probably would be in line as well."

There is a perfectly good reason for this traffic nightmare, he explains.

"This closure is necessitated by the ending phases of demolition of the 121 N. Broad building. This is one of the larger buildings in the footprint of the expansion and not a candidate for implosion."

Translation:

The old Odd Fellows Temple, built in 1893, stands in the way of the addition to the Convention Center. Since it is made of crumbly materials, it won't make a neat pile if they tried to collapse it, and it won't support the heavy equipment they would need to slice it down floor by floor, wedding-cake style, like they did at the Meridian.

Solution?

"Mechanical demolition," says Resta.

Say what?

"Wrecking ball."

Shane LoPresti, manager of Convention Center Parking, said he expects to lose about 30 percent of his business during the road closing. The lot's entrance and exit are on Broad Street just south of Race. Customers will still have access through a back alley, LoPresti said, but many won't know how to get to it.

A dozen drivers, interviewed while they were stopped at a red light on Broad Street today, shrugged off the new disruption, with variations on "What's another thorn when you live with stinging nettle?"

So did Dyshee Pierre, who works in environmental services at Hahnemann Hospital.

"It's a little inconvenience, that's all it is," he said, as he stood by his parked car, waiting for his daughter. "If everybody who lives out of town has to catch the subway, so be it."

In an attempt to relieve some of the congestion, the city has reopened 13th Street between Arch and Race for the duration of the Broad Street closure. That section of 13th has been closed for nearly a year, and after this week, it will be shut down again and remain that way until the expansion is finished in January 2011, Resta said.

Police will be assigned to redirect traffic - 12 officers during the day, 18 in the evening, and 6 overnight. The demolition crews also will be tag-teaming, working three shifts, straight through the holiday weekend. And although eight days may seem like an eternity, he offers a view of the road, so to speak, not taken.

"If they just worked Monday through Friday during the day, they wouldn't be done until July."

Contact staff writer Melissa Dribben at 215-854-2590 or mdribben@phillynews.com.