The West Seattle and Ballard light rail extensions are proceeding through an early planning effort to determine a preferred alternative to be further analyzed under environmental review. In October, the Elected Leadership Group (ELG) winnowed down several segment alternatives by corridor extension to be further analyzed before a final preferred alternative is chosen.

West Seattle and Duwamish

Recommendations by the ELG for the West Seattle / Duwamish segment. (Sound Transit)

In making recommendations for the West Seattle and Duwamish segment, the ELG decided that all of the non-ST3 Representative Project alternatives, with the exception of the Golf Course / Alaska Junction / Tunnel alternative, should be eliminated from further consideration.

The decision is curious given that the Golf Course / Alaska Junction / Tunnel alternative is a full $700 million more expensive than ST3 Representative Project alternative but is estimated to net 500 fewer daily passengers (10,700 versus 11,200). The ELG recommended, however, that Sound Transit staff proceed with further refinements in the Golf Course / Alaska Junction / Tunnel alternative by exploring a more northern crossing of the Duwamish River and possible station locations in the Junction at 41st Ave SW and 42nd Ave SW.

The cost and ridership differentials from the remaining studied options is as follows:

ST3 Representative Project . 11,200 daily passengers.

. 11,200 daily passengers. Golf Course / Alaska Junction / Tunnel. 10,700 daily passengers and $700 million over the ST3 Representative Project.

SoDo

Recommendations by the ELG for the SoDo segment. (Sound Transit)

The ELG decided to carry forward the Surface E-3 and Massachusetts Tunnel Portal alternatives for further review. The Occidental Ave S alternative, which would have allowed for a potential station to serve the commercial corridor along 1st Ave S and nearby industrial areas, was eliminated. This is presumably due to opposition from the Port of Seattle wanting to preserve port activities at all costs, even if the risks are negligible and far outweighed by accessibility benefits to port workers and local businesses. In the Level 3 analysis, Sound Transit will consider shifting existing and new SODO stations closer to S Lander St.

The cost and ridership differentials from the remaining studied options is as follows:

ST3 Representative Project . 35,900 daily passengers.

. 35,900 daily passengers. Surface E-3 . 35,900 daily passengers and $400 million under the ST3 Representative Project.

. 35,900 daily passengers and $400 million under the ST3 Representative Project. Massachusetts Tunnel Portal. 35,900 daily passengers and $200 million under the ST3 Representative Project.

Chinatown-International District

Recommendations by the ELG for the Chinatown-International District segment. (Sound Transit)

For Chinatown-International District, the ELG pushed four of the five alternatives to ST3 Representative Project alternative forward for further review. Making the cut were: 5th Ave S Bored Tunnel (Massachusetts Tunnel Portal), 5th Ave S Mined Tunnel, 4th Ave S Mined Tunnel, and 4th Ave S Cut-and-Cover Tunnel. The alternative for the Surface E-3 cut-and-cover tunnel on 5th Ave S was eliminated from further analysis.

The segment in Chinatown-International District is deeply difficult because any construction will likely heavily impact the local community and existing transit connections, such as electrified bus routes and the streetcar. This is something that Sound Transit will need to be sensitive to, regardless of the final alignment. There is also significant interest in reactivating Union Station, building connections to King Street Station and light rail platforms, and impacts to the Ryerson bus base. Cut-and-cover and tunneled options all present different problems and impacts that will need to be mitigated.

The ridership and cost differentials (inclusive of corresponding SoDo segment) from the remaining studied options is as follows:

ST3 Representative Project . 35,900 daily passengers.

. 35,900 daily passengers. 5th Ave S Bored Tunnel (Massachusetts Tunnel Portal) . 35,900 daily passengers and $200 million under the ST3 Representative Project.

. 35,900 daily passengers and $200 million under the ST3 Representative Project. 5th Ave S Mined Tunnel . 39,500 daily passengers and about the same cost as the ST3 Representative Project.

. 39,500 daily passengers and about the same cost as the ST3 Representative Project. 4th Ave S Mined Tunnel . 35,300 daily passengers and $500 million over the ST3 Representative Project.

. 35,300 daily passengers and $500 million over the ST3 Representative Project. 4th Ave S Cut-and-Cover Tunnel. 35,300 daily passengers and $600 million over the ST3 Representative Project.

Downtown / South Lake Union / Uptown

Recommendations by the ELG for the Downtown, South Lake Union, and Uptown segment. (Sound Transit)

Two alternatives to the ST3 Representative Project were carried forward for the Downtown segment: 5th / Harrison and 5th / Terry / Roy / Mercer. The ELG suggested some refinements to the alternatives with a Seattle Center station near Republican Street for the the 5th / Harrison alternative and a 6th Avenue route through Downtown Seattle for part of the 5th / Terry / Roy / Mercer option.

The cost and ridership differentials from the remaining studied options is as follows:

ST3 Representative Project . 167,800 daily passengers.

. 167,800 daily passengers. 5th / Harrison . 163,300 daily passengers and $200 million over the ST3 Representative Project.

. 163,300 daily passengers and $200 million over the ST3 Representative Project. 5th / Terry / Roy / Mercer. 176,700 daily passengers and $200 million over the ST3 Representative Project.

If the latter alternative is chosen, Sound Transit could still maximize total ridership for minimal cost differential to the 5th / Harrison alternative.

Interbay and Ballard

Recommendations by the ELG for the Interbay and Ballard segment. (Sound Transit)

In Interbay and Ballard, the ELG tossed out five alternatives leaving only the Central Interbay / Fixed Bridge / 14th and Armory Way / Tunnel / 14th alternatives and the ST Representative Project alternative. For the tunnel alternative, the ELG directed Sound Transit staff to consider how that alternative might better support 15th Ave NW and the heart of the neighborhood.

The cost and ridership differentials from the remaining studied options is as follows:

ST3 Representative Project . 17,200 daily passengers.

. 17,200 daily passengers. Central Interbay / Fixed Bridge / 14th . 15,400 daily passengers and $200 million over the ST3 Representative Project.

. 15,400 daily passengers and $200 million over the ST3 Representative Project. Armory Way / Tunnel / 14th. 16,400 daily passengers and $300 million over the ST3 Representative Project.

The two alternatives are considered higher performing than the alignments not carried forward, but their primary drawback is that they are further from Old Ballard. Nevertheless, this could be rectified through further refinement or present an opportunity to consider future land use changes east of 15th Ave NW to complement a station.

Next Steps

Sound Transit will further refine the alternatives to provide further discussion as the transit agency seeks to select a preferred option. Three full corridor options have been released based upon the ELG feedback, which will be the subject of an upcoming article. Sound Transit will also soon provide an update on the remaining options.

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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.