Correction: An earlier version of this story gave the incorrect name for the Commerce Metro Center III building. This version has been corrected.

How will the Orange, Blue and Silver lines squeeze through crowded Rosslyn Station? Careful choreography. (Alberto Cuadra/The Washington Post)

The key cards have been issued. The automatic parking arms have been installed. Parking permits have been secured. Signs have been posted.

While Metro officials are busy making final preparations for the Saturday opening of the system’s first new rail line in more than two decades, businesses and residents from Reston to Tysons Corner are preparing themselves for the possible onslaught of thousands of Silver Line commuters in search of free and easy parking.

Among the biggest potential temptations: Tysons Corner Center mall, home to more than 12,000 parking spaces, including spots in a five-level garage just a short stroll from the Tysons Corner Metro station.

Mall officials are eager to welcome new shoppers. But commuters looking to park? Stay away.

“Our first priority is for our shoppers and mall employees,” said Bob Maurer, a mall spokesman. “We are not allowing commuter parking.”

See where the two phases of the Silver Line will take riders.

It was a deliberate decision on the part of planners to not include parking garages at four of the five new Silver Line stations. The decision was part of the larger push to transform Tysons from a sprawling expanse of corporate office buildings, strip malls and some of the most grinding rush-hour traffic in Northern Virginia into a less car-dependent, walkable model community for the 21st century. Planners hoped the lack of parking would encourage commuters to find other ways to get to Metro.

But that transformation is decades away. And even as Fairfax County officials have invested millions of dollars on bus routes, sidewalks and planning for bike lanes designed to connect riders with the Silver Line, just how many users will take advantage of the options and what traffic patterns will emerge remain unknown.

“We have been doing testing, but not in real-time traffic,” Beth Francis, a spokeswoman for the county Department of Transportation, said about the bus routes and traffic patterns. “The good thing is, all this is in the summer, so we have a bit of time to get things right.”

The first phase of the $5.6 billion rail extension opening over the weekend has four stops in Tysons: McLean, Tysons Corner, Greensboro and Spring Hill. A fifth station, Wiehle Avenue, in Reston, has an underground parking garage with more than 3,000 spaces.

Initially, Metro officials expect about 50,000 riders per day to travel to and from the new stations.

In Tysons, Scotts Run Metro Park and Ride, a temporary lot near the McLean station, has space for more than 700 cars. Tasso N. Flocos, a senior vice president with Cityline Partners, which provided the parking, said Cityline has had a “terrific response” but that spaces are still available.

Kris Morley-Nikfar, a Fairfax transportation planner, said that two other temporary lots — one near the Spring Hill and another near the Tysons Corner stations — could be ready later this year. And he anticipates more interest from developers once the Silver Line is operating.

“I’ve certainly heard rumblings from interested parties,” Morley-Nikfar said. “When the Silver Line opens, property owners will see there’s a demand for parking.”

Even the most ardent fans of the Tysons makeover don’t think there will be enough temporary spaces to meet the demand. Metro’s garage at the Vienna station, which has more than 5,000 spaces, and its garage at West Falls Church, which has about 2,000, routinely fill up before 8 a.m.

And while Tysons has long been home to more parking spaces than people, few are open to the general public.

At Tysons Corner Center, Maurer said officials are installing a key-card system that will restrict access to the mall during non-business hours to discourage commuter parking. The mall will use its network of security cameras and will increase garage patrols, supplementing its security force with Metro and Fairfax police, to determine which cars belong to commuters and which are driven by shoppers and mall employees, he added. Violators will be towed.

He declined to say how much the mall is spending on the initiatives.

New signs at the mall warn commuters that Metro parking is a no-no. At the nearby Tysons Galleria, home to Saks Fifth Avenue, Neiman Marcus and an additional 3,100 free parking spaces, officials said they, too, are stepping up patrols and planning to tow repeat offenders.

“Basically, if you’re not a customer or employee of the center, you’ll be in violation,” marketing manager Grace Tumminelli said.

Northrop Grumman and Mitre, which operates research-and-development centers sponsored by the federal government, have offices on Colshire Drive. They are just up the hill from the McLean station, and they are preparing for possible commuter-parking issues. The companies will increase security, and employees and visitors will have to swipe key cards to use garages and lots.

Matt McQueen, a spokesman for Northrop Grumman, said the companies have talked to Fairfax police about having extra officers available to monitor traffic during the first few weeks of Silver Line operations.

Even in Reston, where the Wiehle Avenue-Reston East station has parking, residents in two neighborhoods petitioned the Fairfax County Board of Supervisors to have their streets designated permit-parking zones, said Maria Turner, a senior transportation planner, who helps manage the county’s program.

Permits are now required to park in the Polo Fields neighborhood, south of the Herndon-Monroe Park and Ride lot near one of the stations in the Silver Line’s second phase, and in the Great Meadow neighborhood just south of Wiehle Avenue. Violators risk having their vehicles towed and a $75 fine.

At Commerce Metro Center III, an office building two blocks from the Wiehle Avenue station, officials have installed a new parking-control system.

Turner said residents in one Tysons neighborhood near the Greensboro station also expressed interest in permit parking, but at this point, the neighborhood doesn’t meet the requirements. Turner said residents will have to wait until the Silver Line opens and the impact becomes clear before their request will be considered.

She said the county will be as “proactive as possible” in addressing residents’ concerns.

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