Getting light rail from the airport to Federal Way just got $460 million more expensive

Sound Transit said Thursday that an extra $460 million will be needed to bring light rail from SeaTac to Federal Way by 2024.

The regional transportation agency was to announce the cost increase during its monthly board meeting.

In 2014, the estimated cost of the 7.8 mile extension was $2.088 billion. As of Thursday, that had risen to $2.549 billion.

Driving the cost increase are both property acquisitions and the rising prices of building materials, said spokesman Scott Thompson. For example, the estimated cost of the necessary right of way for the project has gone from $235 million to $341 million, according to agency records.

The Federal Way line increase comes a year after the Northgate to Lynnwood route added $500 million to its price tag. Its opening has been delayed six months and is now expected to be completed in mid-2024.

Agency director Peter Rogoff said at Thursday’s board meeting that the market forces leading to the increased projects costs “could come to bear” on other Sound Transit projects over the next two decades.

The agency has the wherewithal to handle the added costs as long as federal funding remains viable and there is no dramatic slowdown in the economy, Rogoff said.

A drop in federal funding combined with conditions leading to decreased local tax revenue could lead to “long-term challenges” in delivering projects on time or at all, he said. Sound Transit projects are paid with a combination of federal money and local sales, property and motor vehicle excise taxes.

Currently, the Link light rail system reaches as far south as Angle Lake at South 200th Street in SeaTac. The Federal Way extension will bring it to that city’s transit center.

Funding for the increase hasn’t been nailed down yet.

“The board will have to figure that out,” Thompson said.

The board voted Thursday to move ahead with seeking proposals for the Federal Way extension.

“You don’t get to Pierce County without getting to Federal Way,” said board member Dave Upthegrove, who also is a King County Councilman.

Voters first approved money for the Federal Way extension in 2008, but Sound Transit was forced to put the project on hold when the Great Recession hit, draining tax revenue.

The agency recommitted to the project in 2016’s Sound Transit 3 ballot measure, a $54 billion tax package approved by a majority of the taxing district’s voters but rejected in Pierce County.

Sound Transit is in the midst of pursuing additional federal funding. In August, the project will be budgeted and scheduled.

In order to cut costs for the extension, Sound Transit will be using a design-build contractor.

Design-build uses the same contractor to design and built a project. Previously, two different firms would each bid for those contracts. A request for bids will go out in August, Thompson said.

“We’re hoping we can manage the budget better through this design-build method,” Thompson said.

Sound Transit plans on choosing a contractor in the first half of 2019 and breaking ground later that year.

The Sound Transit board selected the route and station locations in 2017. Stations will be built to service Kent/Des Moines, South 272 Street and the transit center just north of South 320th Street.

Sound Transit estimates the trip from Federal Way to the airport will take 15 minutes.

The route will travel south on its current elevated platform at Angle Lake, cross state Route 99 and then run along the west side of Interstate 5 at grade.

It will return to an elevated section as it reaches the Kent/Des Moines station at South 236th Street.

From there, it continues along I-5 to South 272nd Street.

The route turns toward the existing transit center and ends at a station just north of South 320th Street.

A future extension will bring the route to Tacoma in 2030, Sound Transit said.

This story was originally published July 26, 2018 at 1:50 PM.