(Updated at 2:20 p.m.) Officials from Arlington County and Alexandria gathered near Potomac Yard this morning to break ground on the region’s first Bus Rapid Transit line.

The 4.5-mile Crystal City Potomac Yard Transitway, when it’s completed, will connect the Braddock Road Metro station in Alexandria to the Pentagon City Metro station with a dedicated bus lane. The bus route, which WMATA is calling Metroway, will open Aug. 24 and run from Braddock Road to the Crystal City Metro at first.

“Unless you invest in growth for the future, all you have is memories of the past,” Rep. Jim Moran said. “Many other communities across the country are not growing, yet Arlington and Alexandria are growing. The principal reason is they’re willing to invest in infrastructure for the future.”

The dedicated lanes, already under construction in Alexandria, were approved for a $10.2 million construction contract in February and are expected to be completed by 2015. The right-of-way in which the buses will operate is planned to eventually turn into the Crystal City streetcar system, which will connect to the controversial Columbia Pike streetcar. The streetcar’s two opponents on the Arlington County Board, Libby Garvey and John Vihstadt, attended the groundbreaking and Vihstadt passed out press releases elucidating his support for the transitway, but not the streetcar.

“Even the county’s own press release on the new Crystal City Transitway says it will ease congestion and support both redevelopment and high-density growth,” Garvey said in the release. “This is exactly what we have been saying BRT can do and this is why we don’t need an expensive streetcar. We appreciate the validation of BRT and look forward to watching how it performs.”

Alexandria has not yet committed to building a streetcar system to connect to the Crystal City project — something Arlington officials say the city is “open to” — but the transitway is seen as a piece to connect the two communities even further.

“I think it makes amenities on both sides of the [boundary] line available to people on both sides,” County Board Vice Chair Mary Hynes said. “Our communities are good friends and our borders are kind of invisible. This just knits this place into a much more cohesive place over time.”

The construction is expected to take about 10 months. When completed, the bus will operate in dedicated lanes near Potomac Yard, with stops on Crystal Drive, S. Bell Street, Clark Street, 15th Street, 20th Street and 26th Street. During morning and evening rush hours, the buses will use a dedicated lane south on S. Bell and Clark Streets and north on Crystal Drive, replacing an existing traffic lane. The lane will be open to normal traffic during other times.

The groundbreaking ceremony was put on brief hold in the middle when one of the attendees suffered an apparent seizure. Arlington County medics responded and the individual was transported to a nearby hospital.

Crystal City Business Improvement District President/CEO Angela Fox said the transitway is key for Crystal City in that it’s simply another layer of accessibility for its residents and workers.

“I think one of the most amazing aspects of Crystal City, which we’ve built our marketing and integrity around, is how accessible Crystal City is,” Fox said. “The transitway is just one more step to ensure Crystal City is competitive as we reach the next step. We support any and all things that make transit easier for Crystal City.”