DSC, as Part of the NTP JV, Selected to Provide the SEM Design for University Link in Seattle, WA

DSC's Role

The North Link Transit Partners Joint Venture (NTP JV) was selected to provide final design services for the Sound Transit's University Link project in Seattle, WA.  The JV is comprised of Jacobs Associates, HNTB Corporation, and Earth Tech, Inc.  

DSC will act as a specialty subconsultant on their behalf and will be responsible for designing the following:

• Excavation sequence and support elements for the SEM tunneling works.
• Tunnel waterproofing system.  

Project Overview

The North Link is an extension of the Link Light Rail system in Seattle, WA that extends from downtown Seattle to Northgate. Five new stations will be constructed. The first phase of construction is the University Link, which is the initial segment of the rail system and is comprised of Downtown Seattle, Capitol Hill, and the University of Washington District, the three largest urban centers in the state. The University Link is approximately 3.15 miles, comprising twin tunnels with 17 connecting safety-egress cross-passages, 2 cut-and-cover stations, and an in-line tunnel ventilation shaft at Montlake.

SEM Tunneling

The running tunnels will be constructed using an EPBM. The following sections of the University Link will be constructed using SEM techniques: 

• A 290 ft section of tunnel at the existing Pine Street tunnel,
• part of the Montlake Vent Shaft, which is approximately 135 ft deep and has an inside diameter of 22 ft,
• adits for the Vent Shaft.  The shaft will be constructed in the middle of the two running tunnels and a cross-adit will connect the tunnels,
• 17 cross-passages.  Their locations will be determined during the tunnel construction when the ground conditions can be confirmed.

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