The Philadelphia area, in a transition that began remarkably painlessly last week, is learning to dispense with the Schuylkill Expressway, an unlovely 18-mile stretch of concrete that has been obnoxious and indispensable to a generation of commuters.

At the Gulph Mills exit in the city's western suburbs and at nine of the ramps in downtown Philadelphia, bright orange signs blocked the way Friday, proclaiming, "This ramp closed March 1."

The Schuylkill commuter war, known to the Pennsylvania Department of Transportation as the Schuylkill Reconstruction Project, has begun. Gridlock is expected to be a way of life.

Estimated cost: $160 million (90 percent federal funds, 10 percent state). Estimated duration: three years. Estimated annoyance level: off the scale.

One center of construction in this initial phase is here at Gulph Mills, near the road's junction with the Pennsylvania Turnpike. The other, close to the city's downtown, comes at a 1 1/2-mile stretch where 127,000 cars pass daily. Imagine reducing the eight-lane Shirley Highway in northern Virginia just south of the 14th Street Bridge to four or even two lanes for months, and you'll have an idea of what Philadelphia has in store.

But as the city's commuter war begins, one can hear a perverse pride running through the horror stories that surround the road's past, present and future.

It's a bum of a highway, a metaphor for miscalculation, obsolete long before it's 1961 completion.

But it also inspired the rock-music hit, "The Expressway to Your Heart," written by two Philadelphians and taken to the top of the charts in 1967 by the Soul Survivors. Along with drums, the percussion section featured auto horns.

U.S. 76, running 18 miles from the turnpike in the west past the upscale Main Line suburbs into Philadelphia and on past the southern factory area to the Delaware River, also is the most heavily traveled stretch of highway in Pennsylvania.

"People say that it's the world's longest parking lot," said Lois Morasco, an assistant press secretary for PennDOT. "People say they hate it and they never drive on it; they concede it's in terrible shape, yet now that we're going to reconstruct it, they say we're cutting off their life blood."

The expressway, however, was badly in need of a transfusion.

The word "seamless" would never have applied to the Schuylkill, even when its surface was new. Then, joints between the concrete blocks clicked underneath car wheels with a rhythmic thump mmmmm thump mmmmm thump.

Now, from inside a car, the jolts have been amplified grotesquely and the hum is gone: thump BANG tapoketapoketa thump thump BANG. The surface, in places, has worn through to the understructure.

That's the effect of 24 years of wear, and that's what the project is designed to correct. The entire length, in places, is to be resurfaced, with wider shoulders and more substantial medians.

But, Morasco said, no one can do much about the highway's design. It was created, she said, immediately after World War II, "when America's love affair with the automobile was just beginning." It was designed to accommodate 48,000 cars daily.

From the day it was completed, it carried about 100,000 a day, and today carries closer to 150,000.

Back then, the state also found itself stymied in its quest for land for the road. The Pennsylvania Railroad gave up bits of its right-of-way only grudgingly, and there was no question of taking land from the Philadelphia Zoo. Its builders also had to contend with the rocky, hilly terrain west of the city and with the Schuylkill River. As a result, the expressway's short merging ramps can strike fear into even seasoned commuters.

"If you can drive the expressway, you can drive anywhere," Morasco said.

When it seemed that commuters would be unable to drive it, predictions of disaster abounded. "The media has been riding us," Morasco said. "They're not doing anything nasty but they're following this like it's the greatest disaster since the Civil War."

Elaborate detours were mapped out by highway planners, so commuters who choose to can avoid stretches of the highway that have been reduced from four to two lanes.

In fact, the commuter war's beginning last week was an anticlimax. Planning paid off. "Schuylkill Work: A Smooth Start," read the banner headline in Saturday's Philadelphia Inquirer.

During the morning rush hour, the baffled pilot of a radio traffic helicopter asked where everyone was. Another station set up a mobile home near one of the detour routes to interview expressway refugees, but they went by too fast to say anything.

"The only traffic jam I see is up here," one pilot reported as gridlock persistently failed to materialize Friday.

But wait, the doomsayers began saying as the evening rush hour proved uneventful as well. Monday, they said, will be the real test. And they said it with pride.