Both the Tacoma Dome Link Extension (TDLE) and Ballard/West Seattle Link Extension projects are moving forward with preferred alternatives for environmental review. The Tacoma Dome extension is the latest with the Sound Transit Board of Directors poised to recommend approval of similar segment options of the selected preferred corridor alternatives by the Elected Leadership Group.

Officials hope that limiting the options for environmental study will keep light rail expansion plans on schedule–if not ahead of it–since studying a plethora of options is more time-consuming. Link service to West Seattle and Tacoma Dome is slated to start in 2030, while Ballard Link is tabbed for 2035.

Chosen Tacoma Dome Link Extension Alternatives

TDLE involves four segments stretching from Federal Way Transit Center to Tacoma Dome Station. During the early scoping process, various alternatives had been developed for each of the segments: nine for South Federal Way, five for Fife, six for East Tacoma, and five for Tacoma Dome. Policymakers further whittled down to no more than four alternatives by segment for additional evaluation, all of which would be grade-separated.

For South Federal Way, policymakers have identified the SF 2 West option as the preferred alternative. The South Federal Way station would be centrally located along the commercial node of Enchanted Pkwy S. The general alignment of the segment would otherwise run along I-5. The SF 2 East and SF 8/9 options will also be studied.

Alternatives for the South Federal Way segment. (Sound Transit)

For Fife, the Fife 3B option has been identified as the preferred alternative. The Fife station would similarly be centrally located just north of 15th St E. The general alignment of the segment would otherwise run along SR-99 west of the station. The Fife 3A option will also be studied to tie into South Federal Way segment.



Alternatives for the Fife segment. (Sound Transit)

For East Tacoma, the ET 3A option has been identified as the preferred alternative. The station would be located near E 26th St and Portland Ave E. Two other options, ET 3B and ET 6, will also be studied. For Tacoma Dome, the TD 2 option has been identified as the preferred alternative. The station would be located on E 25th St near E D St. Three other options, TD 2 (cut-an-cover), TD 3, and TD 4 East (in-street), will also be studied. Other cut-and-cover alternatives might be studied if the Federal Transit Administration allows them.

Alternatives for the East Tacoma and Tacoma Dome segments. (Sound Transit)

The Sound Transit Board of Directors will approve alternatives for further study at the end of month. The environmental review process is expected to run through 2022 with the a Draft Environmental Impact Statement due out in early 2021.

Chosen Ballard and West Seattle Link Extension Alternatives

Alternatives for the Ballard and West Seattle light rail extensions. (Sound Transit)

In May, the Sound Transit Board of Directors followed the advice of the Elected Leadership Group and System Expansion Committee Board in selecting several Ballard and West Seattle segment alternatives for further study in the environmental review process. The preferred alternative comes in two flavors for the corridor tails in Ballard and West Seattle while the segments closer to Downtown Seattle, Uptown, Chinatown-International District, SoDo, and Smith Cove are the same. By segment, the preferred alternative shakes out as follows:

From Alaska Junction to Avalon , two options would include elevated alignments with differing station locations in Alaska Junction (somewhere between 42nd Ave SW and Fauntleroy Way SW). As an alternative, two options for underground alignments would also be considered. Third party funding would be required to bankroll the extra estimated $700 million cost to realize tunneling.

, two options would include elevated alignments with differing station locations in Alaska Junction (somewhere between 42nd Ave SW and Fauntleroy Way SW). As an alternative, two options for underground alignments would also be considered. Third party funding would be required to bankroll the extra estimated $700 million cost to realize tunneling. From Avalon to Delridge , the preferred alternative alignment would be largely elevated and follow along SW Genesee St before turning onto Delridge Way SW with a diagonal station between 26th Ave SW and Delridge Way SW. An alternative to this would be an elevated station south of SW Andover St.

, the preferred alternative alignment would be largely elevated and follow along SW Genesee St before turning onto Delridge Way SW with a diagonal station between 26th Ave SW and Delridge Way SW. An alternative to this would be an elevated station south of SW Andover St. From Delridge to SoDo , the preferred alternative alignment would create an elevated crossing of the Duwamish River south of the West Seattle Bridge and turn north to E3 busway. Once reaching S Lander St, the alignment would go at-grade to connect in with the existing system (future Red and Blue Lines) and SoDo Station. An alternative to this would be similar, but put an elevated alignment north of the West Seattle Bridge for a much higher cost.

, the preferred alternative alignment would create an elevated crossing of the Duwamish River south of the West Seattle Bridge and turn north to E3 busway. Once reaching S Lander St, the alignment would go at-grade to connect in with the existing system (future Red and Blue Lines) and SoDo Station. An alternative to this would be similar, but put an elevated alignment north of the West Seattle Bridge for a much higher cost. From Ballard to Interbay , the preferred alternative would be an elevated alignment largely along 14th Ave NW to cross Salmon Bay and reach Interbay. A station would be located at NW Market St and 14th Ave NW. With third party funding, two other preferred alternatives would involve underground tunnels to reach Interbay from Ballard. Stations would be located on or near NW Market St at either 15th Ave NW or 14th Ave NW. An alternative to these options would be an elevated alignment beginning near NW Market St and 15th Ave NW and following closely the the path of the Ballard Bridge to W Dravus St.

, the preferred alternative would be an elevated alignment largely along 14th Ave NW to cross Salmon Bay and reach Interbay. A station would be located at NW Market St and 14th Ave NW. With third party funding, two other preferred alternatives would involve underground tunnels to reach Interbay from Ballard. Stations would be located on or near NW Market St at either 15th Ave NW or 14th Ave NW. An alternative to these options would be an elevated alignment beginning near NW Market St and 15th Ave NW and following closely the the path of the Ballard Bridge to W Dravus St. From Interbay to Smith Cove , the preferred alternative includes an elevated station just north of W Dravus St and transitioning to an at-grade alignment along the BNSF right-of-way with an at-grade Smith Cove station south of the Magnolia Bridge. Several alternatives will be studied for mixed at-grade and elevated alignments and stations.

, the preferred alternative includes an elevated station just north of W Dravus St and transitioning to an at-grade alignment along the BNSF right-of-way with an at-grade Smith Cove station south of the Magnolia Bridge. Several alternatives will be studied for mixed at-grade and elevated alignments and stations. From Smith Cove to Seattle Center , the preferred alternative would transition the alignment underground with a station at 1st Ave N and Republican Street. Several alternatives would involve a mix of elevated and underground alignments and even a station further north in Uptown.

, the preferred alternative would transition the alignment underground with a station at 1st Ave N and Republican Street. Several alternatives would involve a mix of elevated and underground alignments and even a station further north in Uptown. From Seattle Center to Midtown , the preferred alternative would continue as an underground alignment along Harrison Street, Westlake Avenue, and Fifth Avenue. Four stations would be located along the segment in a brand new downtown tunnel, though passengers could make easy connections to the other downtown tunnel station at Westlake. An alternative to this that will be evaluated would put the tunnel and stations further north and east.

, the preferred alternative would continue as an underground alignment along Harrison Street, Westlake Avenue, and Fifth Avenue. Four stations would be located along the segment in a brand new downtown tunnel, though passengers could make easy connections to the other downtown tunnel station at Westlake. An alternative to this that will be evaluated would put the tunnel and stations further north and east. From Midtown to Chinatown-International District, no preferred alternative has been identified. A station could be located shallow or deep on 5th Ave S or 4th Ave S, with extensive tradeoffs for either location and depth. However, whatever option is chosen, a tunnel alignment will be needed to reach the station, after which the alignment could transition to at-grade or remain underground to tie into the East Link corridor (Green Line).

The environmental review process is expected to run through 2022 with the Draft Environmental Impact Statement due out in late 2020.

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Stephen Fesler Stephen is an urban planner with a passion for promoting sustainable, livable, and diverse cities. He advocates for smart policies, regulations, and implementation programs that enhance urban environments by committing to quality design, accommodating growth, providing a diversity of housing choices, and adequately providing public services. Stephen primarily writes about land use and transportation issues.