Project phases: from plans to construction

From idea to operation, it takes a lot of work to bring a complex transit project into service.

Project phases

System expansion project phases: voter approval, planning, design, construction, start of service

Alternatives development: 1 - 1 1/2 years

  • Starting with the representative project from the voter-approved system plan, Sound Transit develops alternatives for study and review, including route and station locations.
  • Community members, stakeholders, commuters, elected officials and partner agency staff provide comments on alternatives, helping to screen for reasonable alternatives to carry forward.
  • Based on input and analysis, the Sound Transit Board identifies a preferred alternative in addition to other alternative(s) to be studied during environmental review.

Environmental review and preliminary design: 3 - 3 1/2 years

As required by state and federal law, Sound Transit then studies potential environmental impacts of the alternatives. This results in the publishing of an Environmental Impact Statement (EIS).

  • Sound Transit obtains data through field work that may include observing and counting traffic, studying natural resources and land use, and monitoring noise.
  • Sound Transit publishes a Draft EIS, followed by a public comment period. The agency responds to those comments in the Final EIS.
  • Sound Transit completes preliminary design work.
  • Based on environmental studies, public input and other data, the Sound Transit Board selects the project to be built, including route and station locations.
  • For projects with federal involvement that require an EIS such as funding or certain approvals, the lead federal agency issues an environmental decision document called a Record of Decision (ROD).

Less complex projects, such as construction of a parking garage, are more streamlined and follow a shortened environmental process that does not require the identification of alternatives.

  • With public input, architects and engineers define what the facilities will look like and how they will operate as well as technical specifications for the stations and tracks.
  • Field work includes testing soil conditions and ground water levels, surveying, and locating utilities.
  • Project teams gather public input at design milestones, typically at 30 percent, 60 percent and 90 percent design completion.
  • Through a public process, Sound Transit selects artists for permanent art installations.
  • Sound Transit obtains private property and easements. This may include relocating businesses and/or residents.
  • Sound Transit acquired permits from local jurisdictions, including land use approvals, noise variances, storm water discharge and wetland impacts. A light rail project requires separate permits from each jurisdiction through which it travels.

Some contracts are issued as "design-build," which means that a single contractor is responsible for both final design and construction. Under these contracts, design and construction often overlaps rather than being sequential.

Construction schedules vary widely from project to project depending on complexity. Some of the factors that can influence schedule and budget:

  • Highly technical project elements, such as tunneling or water crossings.
  • Type of development surrounding project. Noise, time and other constraints to build in dense residential and business settings exceed those for building close to interstate highways.
  • External factors such as labor disputes, material shortages, unforeseen site conditions and weather.
  • Property acquisitions and relocations.

Before the project opens for riders, the testing phase includes a safety certification process including:

  • Simulations to assure that communications, safety, emergency and other systems are operational. The agency checks intersection signals, crossing gates and pedestrian signals.
  • Trains begin running without passengers to help pedestrians, bikers and drivers learn how to travel safely with trains.