University Link Extension is part of the voter-approved Sound Move transit package. For more information about the planning that lead up to Sound Move, visit History: what voters approved.

University Link was included as part of the original Sound Move plan approved by the voters in 1996. 

The Final Environmental Impact Statement for the Sound Move plan (which included University Link) was published in 1999.
In 2000 Sound Transit announced that it would delay the construction of light rail north of downtown Seattle pending further study of the route, schedule and funding options. 

In 2001, Sound Transit completed the North Corridor Alternatives Analysis which evaluated routes between downtown Seattle and the University of Washington. Options evaluated in the study included routes through Capitol Hill and South Lake Union, bridge and tunnel crossings of the Ship Canal and multiple station locations in the U-District.

Sound Transit prepared a Supplemental FEIS for the North Link project (which included University Link) to reflect changes in the route and station locations in 2006.

In 2006, Sound Transit received authorization from the Federal Transit Administration to begin final design on University Link. Final design was completed in 2008. 

Construction began in 2009 and the extension is expected to open for service in 2016. Some of the highlights of the tunnel construction:

Preparing I-5 for the tunneling 

In order for the tunnel boring machine (TBM) to pass safely under Interstate-5, construction crews had to first modify the structures beneath the freeway. This work began in June 2009 and took about a year to complete. During that time the I-5 northbound Olive Way off-ramp was closed to traffic and the express lane Pike/Pine reversible ramp was restricted to southbound transit only. 

Demolition and utility relocation 

Before digging the tunnels, construction crews removed existing buildings from the construction site, had to dispose of any hazardous material in the ground and moved utilities out of the way.

Excavation and tunnel boring 

The first step in building tunnels is to dig a hole where the station will eventually go. The tunneling crews use this hole as a starting point to launch the tunnel boring machines. 

The tunnels for University Link were built by three tunnel boring machines. For detailed information about University Link tunneling:

Tunneling for University Link

Station construction

Each of the underground light rail station is essentially a 30 story building built almost entirely underground. 

For more details on the construction and demolition:

Capitol Hill Station

University of Washington Station

Before Sound Transit can open the line for service, we must ensure that the entire system - including all tracks, stations, communications systems and power and traction systems