Accelerated Federal Way Opening

In a surprising turn of events, Sound Transit CEO Dow Constantine announced Thursday that he now wants the agency to open the Federal Way Link Extension on the 1 Line as soon as possible, and move its opening ahead of the 2 Line's long-delayed Cross-Lake Connection.

Link Light Rail train testing near Star Lake Station, April 2025 (photo by author)

The Federal Way Link Extension (FWLE), after having setbacks of its own, previously settled into a March 2026 opening date. Ever since this target was set, it was believed that the openings of the FWLE and the Cross Lake Connection would not affect each other, because the Cross Lake Connection was expected sometime" in 2025.

However, with the delivery of Cross-Lake service slipping again to early 2026, this could have a knock-on effect on the opening date of Federal Way. After the Apple Cup incident in 2021, Sound Transit instituted a policy of spacing openings at least 6 months apart*. Following this policy would mean a January 2026 opening for the Cross Lake Connection would push Federal Way into July, and a July 2026 opening would push Federal Way Link into 2027. This left open the question of whether Federal Way would really be postponed that long or if Sound Transit would show some flexibility on its 6 month policy. As it turns out, the answer is a third option: accelerate Federal Way. Since the Federal Way extension has made good progress and testing activities have been underway for months at this point, it may be possible to open it as early as this fall.

*Update - Mike Orr and Brent White have pointed out reporting that Constantine has since said that the policy is no longer necessary because the testing that used to take 4-6 months can now be condensed significantly," and that the timing of one opening should not affect the other. This is welcome news, and also means that the opening of Federal Way won't necessitate a 6-month delay of the CLC, which is welcome news.

A map on a Link train shows a Federal Way Downtown Coming Soon" sticker on the 1 Line, without being connected to the 2 Line across Lake WashingtonOpening Federal Way first presents operational challenges

While Federal Way Link being accelerated might be music to the ears of South King County residents, it's not all good news. The lack of a connection to the operation and maintenance facility in Bellevue presented issues for Lynnwood Link, requiring the agency to get creative in order to keep the frequency of trains at 8 minutes during peak times. Operational capacity being stretched thin already, it will likely not be possible to extend the current level of service to Federal Way with existing train storage capacity. Per reporting from The Urbanist, 8.5-mile Lynnwood Link required an additional 53 trains to operate at current service levels. With the Federal Way Link Extension measuring in at 7.8 miles, we should expect it to require almost as many (roughly 48 trains if only comparing by distance). While new southend stations provide potential parking spaces for trains overnight, it would be highly optimistic that this alone would cover the gap needed for full operation**. Thus, opening Federal Way Link early would was thought to require some of the following:

• Reduce peak frequency to 10 minutes, same as off-peak service
• Convert some 4-car trains to 3-car trains to fit more in storage
• Run Federal Way link at reduced frequency

** Update:A Sound Transit spokesperson has clarified to us that there will be no operational impact to headways on the 1 Line from opening to Federal Way", and that they have the storage and maintenance capacity for 4-car trains at 8 minute peak headways once FWLE opens. He also clarified that this is not dependent on access to the OMFE, as they will be able to store, operate, and maintain trains out of [the SODO base] and along the 1 Line while we complete the Crosslake Connection."

Reducing peak frequency to 10 minutes

If peak frequency was reduced from 8 minutes between trains to 10 minutes like it is off-peak, this would require 20% less train capacity to operate a line of the same length. But if the line were 25% longer, the train capacity required to run that line at 10 minutes in theory should be the same as running the shorter line at 8 minutes. If we apply this 25% extension to the 33.15-mile 1 Line, this results in 8.3 miles in additional length, comfortably fitting the 7.8 mile extension.

One downside of this approach is, of course, reduced convenience. No one likes waiting longer for a high capacity transit line that they expect to be very frequent, especially at the busiest times of the day. The other downside is that it reduces capacity of the rest of the line by 20%, meaning trains would be fuller at peak. Some existing mitigations like routes 510 and 515 running into downtown Seattle help with this by giving passengers from Lynnwood City Center and Mountlake Terrace stations an alternative to the train, which frees up some space for the northern section, but it isn't a complete solution.

Reducing train lengths

Given that the line currently runs mostly 4-car trains, Sound Transit could run more trains if they were all 3-car trains. This would allow Sound Transit to make one third more trains with the same number of cars. Considering that (per The Urbanist) Link currently runs 145 trains at peak, one third more would equal about 48 trains, which is equal to the rough estimate of additional trains needed to preserve 8 minute headways! Sounds great, but there are some caveats. First, some trains are already 3 cars. Second, keeping in mind that the main issue is train storage, we don't know exactly how these extra trains are stored. It is prudent to assume that some storage spaces won't be as efficient with 3 car trains as they are with 4 car trains. There might need to be space between trains, which adding more trains would increase and eat into the number of cars a space could hold.

On the positive side, there may be additional space for parking trains overnight on the FWLE, so this could maybe counteract these caveats. So the answer here is a resounding maybe." Were this to be done, it would keep 8 minute frequency at peak, but it would still reduce the capacity of the system about as much as reducing headways because shorter trains have less capacity.

Run Link at reduced frequencies from Angle Lake to Federal Way

The idea here is to run fewer trains per hour on the Federal Way extension, so the rest of the line can keep its capacity and frequency at peak. Sounds unfair, but considering that bus changes for this extension likely can't happen until 2026 still, and considering that this extension is likely to open earlier than planned, I think reduced frequency could be considered an acceptable solution. This could be done by either running a short shuttle line from Angle Lake to Federal Way, or by extending some existing trips to Federal Way while ending most at Angle Lake. Either way, they should require similar new resources.

The FWLE adds about 13 minutes of travel in each direction. Considering that trains currently have layovers factored into the schedule, this means an additional train could add enough capacity to traverse the extension every half hour. Or, if instead assuming the additional train is a shuttle from Federal Way to Angle Lake, it gets trickier since we would only have four minutes of buffer time round trip if we want to keep 30 minute frequency, and we would need space at Angle Lake for the shuttle train. But assuming this, if the FWLE can store one additional train, we could run the extension at 30 minute frequency without affecting capacity or frequency on the main line. If we can store two extra trains, the extension could run every 15 minutes.

Conclusion

While ultimately it seems like these interventions won't be necessary after all as Sound Transit clarified that they will be able to run full service all the way to Federal Way without access to OMFE in Bellevue, this exercise goes to show the scale of our growing system even in its current state. It also shows what kinds of tradeoffs sometimes have to be made when the execution of multiple concurrent projects doesn't go to plan, and the importance of adapting to changes effectively.