Light Rail in Seattle

At a Glance

  • Client(s)
  • Sound Transit (ST)
  • Work Performed By
  • LTK Seattle
  • Project Contact
  • Lloyd Mack, Vice President, Northwest
  • Project Description
  • An all new light rail, commuter rail and streetcar transit system
  • Project Duration
  • Since 1997
  • Project Cost
  • $2.4 billion to date

The Challenge

Hills, and tunnels, and trolleys pose challenges for a new light rail system. 

After decades of planning, Sound Transit (ST) adopted an ambitious regional light rail transit (LRT) network plan in 1996. Since then, voters have approved three funding initiatives to build a 55-mile network of LRT lines extending from downtown Seattle to the north, south and east. The extent and complexity of the regional program required establishing a team of rail transit experts to implement the plan.

Our Continued Commitment

In 1998, LTK was chosen to serve as ST’s engineering firm for the first portion of the plan, Central Link, responsible for light rail vehicles (LRVs) and all supporting systems, including traction power and electrification, signals and communications, system-wide electrical, central control and SCADA (supervisory control and data acquisition), and fare collection.  LTK’s role grew to include conceptual design of operations and maintenance as well as operations planning and capacity analysis. LTK has performed this suite of tasks for all subsequent light rail projects.

The Solutions

LTK assembled a team of engineers and other technical experts to work side-by-side with ST’s staff in Seattle. Our Seattle team applies lessons learned on other LRT projects such as Portland and Denver, where LTK has previously completed significant LRV and systems assignments. LRT development in the Seattle area has unique challenges such as designing the traction power system to control costs in long tunnel sections, adapting overhead contact system designs to accommodate structural conditions on the I-90 floating bridge across Lake Washington, and coordinating LRV designs to achieve level boarding while sharing the Downtown Seattle Transit Tunnel (DSTT) station platforms with buses.  LTK staff from across the country supported the project’s demands, working with ST staff to produce optimized solutions for vehicles and systems.

The Results

Since the initial Central Link line opened in 2009, Seattle light rail has operated reliably and efficiently, providing assurance to ST that it’s LRV and rail systems design decisions are cost-effective and will stand the test of time. By selecting 1,500 volts dc for its traction power system, instead of the more typical 750 volts, ST avoided having to build an expensive subterranean substation at the midpoint of the DSTT.

In 2016, the Link LRT extended service to the University of Washington main campus and from SeaTac airport to South 200th Street. Future openings for lines already under construction are 2021 (UW to Northgate) and 2023 (Northgate-Lynnwood, South 200th-Federal Way and East Link to Bellevue and Redmond). In parallel with the Link light rail projects, LTK also assisted ST in procuring streetcars; designing and building an O&M facility; and managing start-up testing and operations readiness activities for Tacoma Link.

Did You Know?

  • Built on hills and hemmed in by water, locations for transportation facilities in Seattle are severely limited. ST Link’s extensive tunnel sections help overcome inevitable surface congestion.
  • Vehicle engineers, station designers, and operations planners carefully coordinated to ensure that LRV car/platform level boarding would be achieved while continuing to accommodate bus loading in DSTT stations.
  • As ridership grows, ST can lengthen two-car trains to four cars, doubling capacity at a fraction of the cost of building a parallel line.