An Introductory Scenario
It’s 2037! You’re coming in from getting on Link at SeaTac (or Tacoma or along MLK) and are headed to Capitol Hill, UW, North Seattle, Shoreline or Snohomish County. You have luggage. How will Link get you there? Unlike today, you will have to change Link trains. ST proposes having the Green line be the line for SeaTac (as well as SE Seattle, South King County and Tacoma), while the Red line will connect West Seattle with UW and Snohomish County.
Then the next obvious decision you have is this: Where will you change trains? Will you have to go up and down escalators (or worse yet, elevators)?
You’ll have some choices to make. As current plans show, you will be able to transfer at three or four stations – Westlake, International District-Chinatown, Stadium and SODO. Which station is best?
The Initial SODO Station Transfer Design
Early ST documents shown here (https://www.scribd.com/document/352039517/ST3-WS-Representational-Alignment) suggest that the SODO Red line (West Seattle Link) station will be separate from the original Link station. Sound Transit proposes a center platform for the Red line, but the only place that a rider can go from the new platform is to return in the opposite direction on the Red line.
Designing the station this way will mean that anyone transferring between the two lines much change elevation to get to the other line’s platform. No level, cross-platform transfers will be available.
SODO Station as the Best Transfer Station Location
With multiple Link lines, how ST designs the tens of thousands of daily transfers is fundamental to its user friendliness. As noted in the above scenario, there will be three or four stations to transfer between train lines. Of these four stations, two (Westlake and International District-Chinatown) will be completely underground or below the street, so that designing for transfers is extremely costly and difficult because it involves tunneling. At the possible Stadium Station transfer point, the two lines will be close to overpasses and the elevated East Link tracks, so that designing tracks for cross-platform transfers here is also potentially complicated and costly; in fact, current concepts appear to have one of the lines skipping this station altogether! That leaves SODO as clearly the easiest and least expensive station in which to design for this transfer between these two lines.
Prioritizing Transfers at SODO Station
The current plans propose that any transfer between the two lines would always require exiting a platform and going up or down to a new platform level. Having lived in places with cross-platform transfers, I can tell you from personal experience that simply walking across a center platform in a few seconds from one train to the other (no elevation change) is by far the best way to transfer – especially with luggage or a stroller or a bicycle or a wheelchair! It’s also much easier and attractive than even having two train lines on the same track, because you have to get off one train and wait for the other one to pull in.
In fact, many systems take it one step further, scheduling timed train-train transfers (especially at off-peak hours) so that the time penalty for changing trains is fairly minimal. MacArthur Station works in this way for BART, for example.
Two Alternative Configuration Options
To do this, Sound Transit would need to reconfigure how the planned platforms are built. There are a few different options to accomplish this.
- The new center, elevated platform could be designed to serve one direction (such as southbound) of both train lines. The current surface platforms could then serve both lines headed in the other direction. (Perhaps the current surface line could be redesigned to have a center platform by shifting one of the tracks in a later phase — noting that having multiple tracks available would make construction phasing easier). That would mean that only people transferring between West Seattle and the southern portions of the Green Line would have to change a level, and everyone else could have a train at the same level.
- The entire station could be elevated above the street with two center platforms serving four tracks – inside tracks for one branch (like the Green line) and outside tracks for the other (like the Red Line). With that arrangement, transfers between the two lines would also be quite easy. Of course, transferring between West Seattle to the southern portions of the Green line would require two level changes in this configuration.
A comment on East Link trains: Obviously this station doesn’t allow for transfers to East Link; those riders would have to change trains in Downtown Seattle. However, having a lower frequency of trains to West Seattle at SODO Station (compared to the combination of Red and Blue line trains further north) would actually make it more operationally feasible to have a timed-transfer at this station. It also would allow for the station design at International District-Chinatown to prioritize connecting east and south direction train transfers in that design. For example, the new southbound Green line platform at International District/Chinatown could be built just east of the current northbound Red/Blue line platform at this station so that riders heading to SeaTac from Bellevue would have a same-level transfer.
A final point is that ST will need to turn around trains to and from West Seattle in SODO for several years until the Downtown tunnel opens. During that interim period, a cross-platform transfer could significantly reduce the transfer hassle for riders. Imagine if every West Seattle shuttle train rider had a longer-distance Link train to board waiting at the same platform for them (and vice versa)!
Why We Must Act Now
Sound Transit is now initiating studies on how operations will work after the opening of the West Seattle segment (2030 in ST3 materials), and in the new configuration (2035 in ST3 materials). ST hasn’t yet presented about on how many people will transfer between the two lines. I think it’s worthy to transit advocates to get Sound Transit to rethink the initial station track plan at SODO, and instead prioritize a Red/Green line cross-platform design objective into the design. If the current SODO station plans get built and this is ignored, we will be dooming thousands of riders each day for decades to changing levels to continue their light rail trips. Let’s get Sound Transit to design an easy transfer now to prevent this hassle or an expensive fix later!