The 10-mile, $2.3 billion Bay Area Rapid Transit Silicon Valley Berryessa Extension is getting powered up and remains on track for completion by fall 2017. Here in town, test trains are expected to run on the tracks leading into the Milpitas BART Station later this month and into the coming year, according to Santa Clara Valley Transportation Authority.

On Sept. 2, VTA provided the media with a “behind the scenes” look of the Milpitas BART infrastructure that will power the system. The press tour included a look at the contact rail or “third rail,” which touches the sides of the train tracks and powers the trains.

At the tour, VTA energized around three miles of the 10-mile Berryessa extension, from the Milpitas substation — on the north side and across the street from the pending station off Montague Expressway — with the third rail being energized in segments, according to VTA spokesperson Brandi Childress.

“The segment that is currently being powered up is from Kato Road up to Warm Springs. That’s about three miles of track (or 30 percent). We will then start energizing sections of contact rail from Kato Road to Railroad Court,” she added.

The rail was electrified and then turned off during the media tour. But Childress said the completed tracks could be energized at any time to run test trains. She added all of the track in Milpitas leading up to and out of the Milpitas BART Station was expected to be completed by October.

“We will be going inch by inch, going down the line and powering the area,” Childress said. She added electrifying the third rail for part of the tracks meant the start of a year-long process for testing the train tracks as well as the entire train operating system.

The Milpitas and Berryessa BART stations, which are being built by VTA and will be operated by BART, will be the first two stations of their kind in the South Bay. BART has historically served Alameda, Contra Costa and San Francisco counties with stations from Fremont through Daly City and Richmond, among other lines.

Childress said it was important for commuters to recognize the difference in VTA’s light rail train, which are powered by overhead lines and meant to coexist with pedestrians and vehicles, versus the BART heavy rail system. That system is a closed with a restricted right of way that keeps it separated from vehicle, bike and pedestrian traffic.

Moreover, Childress said it was important for the public to know to stay off BART tracks, since the contact rails alongside the train tracks will be powered by 1,000 volts of electricity, and contact with them could result in death by electrocution. She added powering up part of the train tracks signifies the near completion of the construction portion of the project.

“We want the public to realize that although a lot of the construction is completed, there is a year of testing that needs to get done. We need to tell the public even though there are trains on the track, we are not ready for them,” Childress said. “We don’t want people to get frustrated, this is how you roll out a rail system. It involves operator training, and while that is happening we will finish the campuses and include bus stations, park and rides and tying that all together.”

The station, the newest gateway into the city, continues to take shape near the corner of Montague Expressway and East Capitol Avenue adjacent to the Great Mall, as critical elements come online including a pedestrian overcrossing, which will connect the BART station to the light rail station.

Childress said the completion of track leading into the new Berryessa station and the powering up of that line is at least six months away.

The Milpitas BART Station, which is supposed to offer less than one-hour trips to San Francisco from the South Bay, will also feature a ground level concourse, below-ground boarding platforms, a connection to VTA’s light rail station, a private shuttle, a VTA bus transit station and a loading area for passengers.

The line will proceed in the former Union Pacific Railroad right-of-way through Milpitas, the first station, and then to Berryessa at the second station. If future funding is secured, the line is planned to extend to downtown San Jose and eventually Santa Clara.

According to VTA, the line and track systems for the entire 10-mile extension costs $772 million. Also, a six-story parking garage in Milpitas and a seven-story garage in Berryessa together cost an additional $86.9 million.

The Milpitas and Berryessa stations are expected to see an estimated 23,000 daily passengers on opening day, with 13,000 expected at Berryessa and around 10,000 at the Milpitas station, Childress said. She added those numbers are expected to double by 2030.