On Monday, the Sound Transit West Seattle and Ballard Link stakeholder advisory group, which includes transit advocates, prominent community members, and business and labor leaders, moved further along the process of selecting alignments and station locations for the West Seattle and Ballard light rail lines.
In Monday’s meeting in Union Station’s Sound Transit boardroom, agency staff briefed the group on siting and alignments in Sodo and Chinatown. They also briefed the group on water crossings at Salmon Bay and the mouth of the Duwamish river.
The advisory group will eventually pass recommendations to a subcommittee of the Sound Transit board, which in turn will recommend the ultimate preferred alternative to the board as a whole.
In breakout sessions conducted over pad thai, the advisory group discussed the alignment and station locations of the new West Seattle line’s Sodo station. The advisory group also discussed the location of the new Chinatown/ID station, which will have far-reaching impacts on the future of the light rail system.
The Chinatown station, and the segment of the new line closest to it, was the subject of intense discussion, with good reason. It’s the centerpiece of the project, and it could have the most disruptive construction impacts of any Link project so far.
Tough choices for Chinatown/ID station and alignment
The future Chinatown station is one of the most critical elements of the new Link line. It will be the southern terminus of the new downtown tunnel, the site of hundreds of thousands of intra-Link transfers every day, and the light rail network’s busiest multimodal hub, with connections to Sounder, Amtrak, public and private buses, and the Seattle streetcar.
The station and alignment’s siting and design will have permanent impact on Link’s capacity, headways, and expansion potential. Sound Transit is committed to making the Chinatown station a central transfer hub, so it has to be built adjacent to the existing Chinatown/International District Link stop next to Union Station.
Construction in Chinatown and Pioneer Square is complicated. Much of the area is infilled tideland, which would liquefy during an earthquake. Liquefaction aside, the loose soil requires deep foundations for newer construction, and would force Sound Transit to make a deep bore tunnel even deeper than in most areas of the city.
Plus, many of the buildings in the area are built on pilings, since the neighborhoods are the city’s oldest. Those pilings could be obstacles for any alignment, and might not be replaceable with a new foundation. Demolition isn’t a way out of that problem: a large slice of the area—and King Street and Union Station themselves—are historic landmarks, or in historic districts.
4th Avenue vs. 5th Avenue
Sound Transit’s “representative alignment” is under 5th Avenue, with a station perpendicular to King and Jackson streets and parallel to the current Chinatown/ID station. During the first round of outreach with the Chinatown and Pioneer Square neighborhoods, there was strong demand for siting the line and station on 4th Avenue, or under Union Station.
From a rider’s perspective, that alignment is probably the ideal option: it will allow for easy underground connections to the heavy rail platform at King Street Station to the west, and existing bus and Link service to the east. Pedestrians wouldn’t have to deal with the current long, dangerous scrabble across busy intersections to move from Link to Sounder.
Building the 4th Avenue alignment would also prevent 5th’s negative construction impacts on the surrounding neighborhoods, whose residents are poorer, more diverse, and in the case of Chinatown, older than the rest of the city. The construction would also take place in the middle of one of the Puget Sound region’s largest groupings of businesses owned by people of color.
The 4th Avenue cut and cover tunnel would have impacts on underserved communities as well: the staging area for the alignment would be sited at the current location of an affordable housing development and a halfway house at 4th and Jefferson.
4th Avenue traffic chaos
However, the 4th Avenue alignment would also create significant challenges. For one, 4th Avenue is the busiest surface corridor on the south end of downtown. According to Sound Transit, approximately 33,000 vehicles traverse the Chinatown section of 4th Avenue South every day. It’s a major freight corridor, and the primary route for Metro buses to enter downtown and exit Ryerson Base.
Closing the street, even partially, for construction would be enormously disruptive. To build a 4th Avenue alignment using cut and cover, Sound Transit estimates two separate segments of the street would have to be closed for a minimum 18 months each.
The 4th Avenue viaduct
Even a deep bore tunnel under 4th Avenue South would require Sound Transit to close the 4th Avenue corridor south of Jackson. That’s because the 4th Avenue Viaduct, which carries the street over the BNSF main line and rail yard, would have to be replaced as part of any 4th Avenue construction process.
Its lifespan ends sometime in the 21st century, though the SDOT representative on hand, Colin Drake, the agency’s ST3 manager, didn’t have the exact date available. Therefore, 4th Avenue presents something of an opportunity. Rather than closing major sections of the grid at various times, agencies could minimize pain by completing two major projects at once.
Sound Transit staff said that, if the 4th Avenue alignments were chosen, they would hope to partner with SDOT to complete the project. Drake implied that he supported that idea, though he couldn’t commit to it. Nor could Drake make a firm statement about the state of the bridge or the need to replace it, other than to say that it hadn’t been identified as one of the bridges in dire need of immediate repair.
“So does the bridge need to be replaced?” said Maiko Winkler-Chin, the executive director of the Chinatown-International District Public Development Authority, while her breakout group was discussing the 4th Avenue alignments.
“That’s the right question,” joked Drake, to general laughter.
The advisory group asked Sound Transit staff to continue studying all 4th and 5th Avenue options, though the staff present seemed to favor 5th Avenue, or at least a shorter list of projects. The group did eliminate a mined station directly underneath Union Station, which would have been extremely expensive and risked damage to the historic landmark.
Sodo station & alignment
The new Sodo alignment, for the line to West Seattle, presents fewer difficult choices. But it will still play an outsize role in capacity, travel times, and headways.
Sound Transit staff presented several alignments—on Occidental Avenue, the E3 Busway, 6th Avenue South, and in a tunnel—and the group recommended that Occidental, the tunnel, and the Busway go forward in the engineering process. 6th Avenue offered some ridership gains and a slightly enlarged walkshed, but the alignment presented some costly engineering challenges, and would have increased travel times to West Seattle.
An elevated route down Occidental Avenue, with a stop around Lander Street, would add the most ridership of any Sodo alignment. The stop would be close to Starbucks headquarters, the Port, industrial employers, and a growing row of bars, restaurants, and retail on 1st Avenue South.
However, group members from industrial and business backgrounds were concerned about negative impacts on freight mobility. Occidental is home to plenty of loading docks for businesses and manufacturers. Similar concerns contributed to the death of Chris Hansen’s Sodo Arena proposal.
Busway and track interlining
Staff presented two options that would reduce overall transit capacity from the corridor’s maximum potential. One, constructing a surface-level track on the full length of the current E3 Busway, would displace dozens of southbound buses.
The other, interlining West Seattle service with the existing Link track, would severely limit capacity. Since Central Link’s right of way isn’t completely separated from traffic, and will be at full capacity at when the West Seattle route comes online, the new trains would have to run at lower speeds and longer headways.
The busway was carried forward, but track interlining was not.
According to Sound Transit spokesperson Kimberly Reason, all of the alignments that the group approved for further analysis—the tunnel, Occidental, or the representative project—would require some use of the E3 Busway right of way. The Occidental alignment would be elevated for its section of E3, while the tunnel’s portal at Massachusetts would be at grade on the busway.
Water crossings at Salmon Bay and the Duwamish River
Sound Transit staff didn’t tip their preference for the new crossing, but they did discuss some constraints.
Any crossing will have to win approval from a battalion of permitting agencies at the federal, state, and local level. The crossings also have to respect the treaty fishing rights of area tribes, which actively fish both waterways.
Either end of a crossing has to be chosen carefully: the ideal site for a preferred alignment might lie under private property, which would be costly to purchase, or could lead to an ugly (and risky) eminent domain fight.
Also, as mentioned above, Native American nations have fished and lived on both waterways for centuries. That means that any site could have archaeological and historical artifacts buried in the soil.
Sound Transit staff haven’t eliminated any crossing type (tunnel, high bridge, drawbridge) from consideration.
Corrections: This post has been updated to reflect the location of the proposed 4th Avenue cut and cover tunnel staging site, and the relationship of the Sodo tunnel and Occidental Avenue alternatives to the E3 busway, and to clarify that the 4th Avenue viaduct partnership with SDOT is provisional.