Area light rail continued its southerly march down the Interstate 5 corridor with the official opening of its Angle Lake Station in SeaTac last Saturday.

And regional transportation leaders hope the ride doesn’t end there.

Sound Transit officials said the 1.6-mile extension from Sea-Tac Airport to South 200th Street will bring more mobility to King County commuters and ease area traffic congestion. The South 200th Link Extension project opened four years earlier than envisioned in the 2008 voter-approved ST2 plan, and is trending $40 million under its $383 million budget, ST officials said.

According to Sound Transit CEO Peter Rogoff, the success of the latest project can be attributed to a collaborative design-build team and to a federal partnership that helped secure funding to speed up construction. The Port of Seattle has been a key partner, too, having worked with Sound Transit during construction of the extension, ST officials said.

“It’s a very symbolic moment in our continuing effort to move south,” Rogoff said during a dedication ceremony at the new link station on a sun-kissed Saturday. “We are funded to get to Kent-Des Moines, and with the support of the voters in November (on a $54 billion ST3 measure), we will build on to Federal Way and to Tacoma.”

Rogoff said Sound Transit is set to complete environmental work by the end of the year for extending service to Kent, Des Moines and Highline College.

The Federal Transit Administration provided $37.3 million in grants to the new line at SeaTac, including $10 million in Transportation Investment Generating Economic Recovery (TIGER) funding. Washington state provided $5.2 million in Regional Mobility Grant funding, and the Puget Sound Regional Council awarded $7 million in Congestion Mitigation Air Quality dollars for the project.

The latest extension – from Sea-Tac Airport to South 200th Street and 28th Avenue South – consists of an elevated guideway and a station that will serve as the southern terminus for the South Transit Link until the extension to Kent-Des Moines opens in 2023. Angle Lake Station’s 1,050-stall garage, 70-space surface lot, van pool parking and passenger drop-off/pickup area will help address the demand for parking. The facility offers covered waiting areas and a nearby transfer area for local and RapidRide bus connections.

Four charging stations for electric vehicles are in the garage, and storage for 52 bicycles is available on site.

The rail line from Angle Lake connects to the existing 18.8-mile link system operating between Sea-Tac Airport and the University of Washington. It will serve 5,400 boardings each weekday by 2018, Sound Transit said. Riders will have a four-minute trip to the airport, a 41-minute trip the Westlake Station downtown and a 48-minute ride to the UW.

Angle Lake represents the third of Sound Transit’s light rail stations to open in the last six months. It was ST’s first completed design-build project.

ST3 looms for voters

To stretch farther, Sound Transit faces it biggest test.

ST3 proposes to complete a 116-mile regional system — five times larger than it is today — that reaches Everett, Tacoma, the Seattle neighborhoods of Ballard and West Seattle, and new Eastside destinations of Redmond, south Kirkland, Bellevue and central Issaquah.

According to Sound Transit, the estimated cost to implement ST3 is $53.8 billion in year-of-expenditure dollars, of which $27.7 billion is to be financed with new local taxes.

Opponents contend ST3 – or Proposition 1 – is too expensive, takes too long to build and doesn’t little to ease congestion.

Proponents of the proposition support the plan as an investment in infrastructure for the future, saying it creates a system that provides commuters options to help them avoid already-congested freeways and prepares the region with high-capacity transit for the million more people moving here in the next 25 years.

In the South King County service area, $8.4 billion of the proposed total $53.8 billion in improvements would be used for:

• Light rail between Angle Lake and Federal Way by 2024

• I-405 and State Route 518 bus rapid transit between Lynnwood and Burien by 2024

• An infill light rail Station at Boeing Access Road by 2031

• Sounder South improvements, including parking/access, 10 car platforms, and additional track and signals between 2024 and 2036

• Bus on Shoulder program implementation between 2019 and 2024

• Ongoing system-wide improvements using innovation, system access and transit-oriented development funds; expansion of express bus service; and studies of West Seattle to Burien, connecting to Renton via Tukwila.

To learn more, visit soundtransit.org.

– Reporter Robert Whale contributed to this story.