Frustrated drivers who wish they could fly over the maze of merges called the Springfield Mixing Bowl should get some relief today with the opening of a mile-long flyover designed to route thousands of cars and trucks 10 stories into the air and set them down well beyond the traffic tangle.

The new ramp, scheduled to open this afternoon, is a milestone in one of the nation's most ambitious highway projects.

By linking the inner loop of the Capital Beltway to the southbound lanes of Interstate 95, the two-lane ramp is the first piece of construction to directly help traffic get through one of the region's most perplexing interchanges: the convergence of the Beltway, Shirley Highway and I-95. Until now, most of the project has been devoted to improving secondary roads around the area.

Highway officials said that once drivers adjust to the new ramp, it should ease traffic across the region. Most of the miles-long rush-hour backups on the inner loop are caused by thousands of cars trying to go south on I-95. All drivers should find a smoother ride through the Mixing Bowl, officials said, because less traffic will be trying to navigate the interchange.

"Relieving 20,000-plus vehicles a day from a single choke point where all of those vehicles have to merge obviously will have a regional impact on traffic from all directions," said project manager Larry O. Cloyed. "In terms of the interchange itself and regional traffic flow, this is the most significant . . . improvement to date."

Officials hope to have the flyover open by this afternoon's rush hour.

The Mixing Bowl construction project aims to unravel one of the most dangerous bottlenecks on the East Coast, which more than 430,000 cars and trucks pass through daily. By the time the nearly $700 million project is finished in 2007, eight years after it began and at nearly three times its original projected cost, the interchange will have more than 50 ramps and overpasses, and I-95 in that area will comprise 24 lanes.

Project officials said a ramp connecting the northbound lanes of I-95 to the outer loop of the Beltway is scheduled to open by the end of next year. Beyond that, several major ramps and bridges connecting I-95 and the Beltway west of the interchange, as well as reconfigured lanes on I-95 and Interstate 395 through the Mixing Bowl, are scheduled to open in the spring of 2006.

On Friday, outer loop motorists heading south on I-95 should also get a break, when a second lane is scheduled to open along the exit off the Beltway.

Still, officials worry that the new ramp could initially cause confusion and worsen traffic.

Until mid-summer, when the ramp's approaches are finished, drivers will funnel into a single lane to get onto the ramp, where both lanes will be open, only to constrict back to a single lane before continuing on I-95.

Transportation officials also said that despite radio advertisements and other attempts to get information out about the new flyover, traffic could be a mess as drivers accustomed to exiting on the right have to move to the left. Officials said they will leave the old exit for I-95 open for at least a few weeks as drivers adjust.

"Given the enormous volumes we're talking about, inevitably there will be drivers who are confused," said Lon Anderson, spokesman for AAA Mid-Atlantic. "That means slowing down, holding things up, causing crashes. The best we can hope for is that it goes relatively well."

Cate Pederson, who commutes from Alexandria to Stafford County, said she just doesn't get it. "You're supposed to be in the left lane for the flyover?" she asked. "It looks like the flyover is on the right."

Pederson also said that she was unaware that the new ramp was opening today and blamed highway officials for not doing a better job of publicizing the flyover. "We're all operating in a vacuum of information," Pederson said. "There's no signage, nothing. No one knows where that lane's going to feed."

Highway officials said that until today they have kept new signs covered, fearing they would confuse drivers.

"Over the first few days there could be a little confusion, and that could create some slowing down," said Cloyed, who predicted that trips would be shortened by as much as 10 minutes when all lanes are open on the ramp's entire length.

At a height of 100 feet, the $31 million ramp is one of the tallest of its kind in Virginia. Consequently, it presented its own challenges. Builders had to consider how wind, ice, snow and noise would affect drivers, not to mention jitters and curiosity.

"I thought we should go ahead and put a scenic overlook up there," joked project spokesman Steve Titunik. "Put up some telescopes and have fun with it."

Instead, officials built taller-than-normal parapets on one side of the ramp, to cut down on high winds and the temptation of drivers to peer over the side. On the ramp's other side are 12-foot sound walls to keep the rumble of tractor-trailers from annoying neighbors.

De-icing gadgets, similar to those used at airports, were deemed too expensive, so a dedicated group of trucks and plows will be assigned to the span and others in the interchange during winter months.

Officials also said mile markers would eventually be put on the ramp so that when broken-down motorists call for help, they'll know where they are amid the puzzle of bridges and ramps.

Janine Taylor doesn't care so much about the specifics -- she's just glad the ramp is there. "We're all pretty pumped," she said of the carpoolers she rides with from Alexandria to Stafford each evening.

Merging into the Mixing Bowl every day is a white-knuckle adventure, she said.

"It's horrible," she said. "You're taking your life in your hands when you go through."

Would she miss the excitement?

"Uh, no," said Taylor, laughing.

A view of the flyover from the northbound lanes of I-395 shows the 12-foot-high sound walls installed on the southbound overpass to prevent traffic noise from disturbing residents.The flyover's grooved roadway is designed for better traction in wet and icy conditions, and the span will be monitored closely in winter months. Vehicles traveling north on Interstate 395 pass beneath the new ramp linking the Capital Beltway's inner loop to the southbound lanes of Interstate 95.