Get an aerial view of Metro’s Silver Line, set to open July 26, as it snakes its way through Tysons Corner and on to Reston, Va. (McKenna Ewen, Lee Powell and Osman Malik/The Washington Post)

Since Sunday, hour upon hour, from just past dawn until after midnight each day, Metro’s new Silver Line has been taking a pounding.

In a week of testing leading to Saturday’s scheduled start of passenger service on the long-awaited rail route, five to 10 trains per hour, without passengers, have been rolling out of the new ­Wiehle-Reston East station, following 11.7 miles of new tracks to East Falls Church. And another five to 10 trains per hour have been traveling the opposite way, from the East Falls Church Metro station to Wiehle Avenue.

After countless rounds of political debate, stop-and-start technical planning that began a half-century ago and the arduous, multibillion-dollar construction work that started in 2009, the Silver Line faced its most important challenge this week.

“It’s the first time that the infrastructure — those tracks, those signals, those switches, all that equipment — has actually seen any real frequency of trains,” Metro spokesman Dan Stessel said. “A train every six minutes at rush hours, both directions, and every 12 minutes through the middays. And for this long. It’s the first time, ever.”

Several hundred trains have rumbled along the route during “simulated service,” putting the intricate rail mechanisms through their paces.

And the result: The Silver Line, Stessel said, “is ready for its close-up.”

Well, time will tell. There are a lot of moving parts, human and mechanical, involved in the new rail line. And like any public transit system, Metro rarely, if ever, runs flawlessly.

Tens of thousands of new riders are expected to eventually use the Silver Line, meaning tens of thousands of people learning — among many other things — how to get where they’re going, how to pay fares, where to stand on escalators, how to behave in a crush of passengers and what to do if they’re caught in closing doors.

And parking: There’s a 2,300-space garage at Wiehle-Reston East, plus a 1,000-space lot. But there is no parking at the four new stations in the Tysons area — McLean, Tysons Corner, Greensboro and Spring Hill. Will new Metro users show up in cars, anyway?

Speaking to reporters Thursday, Metro General Manager Richard Sarles said repeatedly that he has no worries. “We are prepared,” he said. “We’re ready.”

He also noted, “It’s summertime and we’re going into August, so certainly, other than the people who want to be first, you’ll see lighter ridership now than in the fall.”

After Saturday’s opening, the next big test will come Monday morning, when the first workday rush-hour crowds show up at the new stations. Unlike Saturday and Sunday, when trains will run every 12 minutes, the Silver Line, like other lines, will operate on a rush-hour schedule from 5 a.m to 9 a.m. and from 3 p.m. to 7 p.m. on weekdays, with trains every six minutes.

Starting at 10:30 a.m. Saturday, about 90 minutes before the first passenger-carrying Silver Line train leaves the Wiehle station — “the inaugural train,” Metro calls it — an invitation-only ceremony will be held at Wiehle featuring remarks by a dozen or so public officials, including Virginia Gov. Terry McAullife (D) and federal Transportation Secretary Anthony Foxx. There will be a ribbon cutting. And then, about noon: All aboard.

“We’re now in the fifth day of simulated service on the Silver Line, and I’m pleased with what we’ve seen,” Sarles told the transit agency’s board of directors Thursday. He said this week’s simulation “allows us to ensure that everything, from signals to traction power to rail-car mechanics, performs in an integrated fashion throughout the system.”

He said Virginia officials this week issued certificates of occupancy for the five new stations. And the Tri-State Oversight Committee, which monitors Metrorail safety, has approved the start of service.

“With the occupancy certificates and the safety certification in hand, along with five successful days of simulated service under our belt, the system is ready to welcome aboard our customers,” Sarles declared at the directors meeting.

The route that is opening Saturday is just the first phase of the Silver Line. It cost about $2.9 billion, or $150 million more than initially planned. The second phase, extending 11.4 miles west from Reston to Loudoun County, just beyond Dulles International Airport, is expected to cost $2.7 billion and open in 2018.

That would bring the overall Silver Line tab to $5.6 billion.

By creating a rapid-transit connection between the region’s two biggest economic hubs — Tysons Corner and downtown D.C. — and also linking the Dulles corridor to the Pentagon, the Silver Line is expected to gradually transform traffic-choked Tysons into a greener, transit-oriented, quasi-urban community, economic planners say.

They foresee a booming Tysons economy based in a skyline of office towers and, below, walkable spaces filled with trendy retailers, restaurants and bars — a much larger version of Metro-influenced Clarendon and downtown Bethesda.

The departure of the inaugural train Saturday will signal the start of that process — the official beginning of Silver Line service.

But the new line won’t instantly spring to life. Rather, it will become fully operational over a span of 70 minutes, between about noon and 1:10 p.m., which could confuse some passengers waiting for trains in older stations along the Silver Line route.

The reason is the process by which Metro plans to transition within that 70-minute period from simulated Silver Line service to actual service.

Since Sunday, in this week’s tests, five to 10 trains per hour have been leaving Wiehle Avenue and traveling through the four Tysons stations en route to the decades-old station in East Falls Church, which previously had been used only by Orange Line trains.

From East Falls Church to Largo Town Center and back, the Silver Line shares tracks for various stretches with the Orange and Blue lines.

During simulated service, trains leaving Wiehle Avenue have not been picking up riders until they reach East Falls Church. From there to Largo, and on the return trips, the trains have been designated Orange Line trains for the public, although Metro considers them simulated Silver trains.

The simulated service will continue right up until noon Saturday, meaning there will be simulated Silver trains — labeled as Orange trains — coursing through the system when the inaugural train pulls out of Wiehle amid much hoopla.

After the inaugural train covers the 11.7 miles of new tracks and is about to arrive at East Falls Church, all the simulated Silver trains headed in the other direction, from Largo toward Wiehle, will cease to be labeled as Orange. Signs at the front of those trains will change, mid-trip, to read “Silver” instead of “Orange.”

Which means that shortly before 12:30 p.m. Saturday, as the inaugural train approaches East Falls Church, some westbound passengers who boarded trains labeled Orange, with the terminus of East Falls Church posted on the cars, will suddenly find that they’re on trains redesignated as Silver and bound for Wiehle Avenue.

Not to worry, though: The stops will be the same as the Orange Line’s, except for the five added stations at the end, in Tysons and at Wiehle Avenue.

As for eastbound simulated Silver Line trains running ahead of the inaugural train, those won’t change their designations from Orange to Silver until they reach the Largo Town Center station and start back in the other direction.

Finally, about 1:10 p.m., when the inaugural train rolls into Largo, simulated service will be over. All Silver trains in the system will have been relabeled as such. And the new line, decades in the planning and years in the building, will officially be a reality.

Asked after Thursday’s board meeting if there are any aspects of the Silver Line’s opening that worried him, Sarles spoke confidently, citing “the extensive testing we’ve done, the extensive planning and the simulated service, which has gone well.”

He said, “I am really not anxious or losing sleep over the start of service.”