Map of the Week: Sound Transit’s New System Expansion Map

New ST3 map. (Sound Transit)

Sound Transit upgraded its old ST3 map with a cleaner new map and website. The old map helped sell the package to the regional electorate that voted 54% in favor of the 25-year investment last year. The new map is more elegant and legible. The interactive map also includes slightly updated quick facts on the new lines voters authorized.

Click on the Ballard line, for example, and you’ll quickly see Sound Transit’s expected operational date of 2035 and see the movable bridge crossing of Salmon Bay that the transit agency is heavily leaning toward–despite the obvious advantages of a tunnel crossing: no service disruption for passing ships and no costly, time-consuming, and ultimately perhaps only partially successful environmental mitigation for sensitive salmon runs.

New Systems Expansion map with legend. Visit website for interactive version. (Sound Transit)

ST3 promised light rail to the Tacoma Dome by 2030, with a trip to Sea-Tac taking 35 minutes. (Sound Transit)

On the positive side, the new map continues to reflect the split spine concept Sound Transit unveiled in December 2015. Under the concept, the Ballard line continues to Tacoma (as the green line) and the West Seattle line turns north to Lynnwood as the red line–and will continue on to Everett by 2036. This should increase the operational efficiency of each line by avoiding a marathon 65-mile route from Tacoma to Everett that’d take at least two hours each way. Meanwhile, the new map’s blue line would be a Lynnwood to Redmond via Downtown Seattle line.


Draft Plan expansion concept for the region. (Sound Transit)
Draft Plan expansion concept for the region from last year. (Sound Transit)

Not a lot has changed from the old map, but the new map is easier to read and worth perusing. The new map is also available in a PDF version and the website includes a newly-formatted project list. Here’s how long Sound Transit estimates you’ll have to wait for ST3 light rail projects:

Timelines on ST3 projects reflecting how must faster than the initial proposal. (Sound Transit)

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Doug Trumm is The Urbanist's Executive Director. An Urbanist writer since 2015, he dreams of pedestrianizing streets, blanketing the city in bus lanes, and unleashing a mass timber building spree to end the affordable housing shortage and avert our coming climate catastrophe. He graduated from the Evans School of Public Policy and Governance at the University of Washington. He lives in East Fremont and loves to explore the city on his bike.

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Click on the Ballard line, for example, and you’ll quickly see Sound
Transit’s expected operational date of 2035 and see the movable bridge
crossing of Salmon Bay that the transit agency is heavily leaning
toward–despite the obvious advantages of a tunnel crossing: no service
disruption for passing ships…

What makes you think that the train will ever be delayed by a passing ship? If you can provide evidence that it would, than I would take this fear seriously. But as I see it, this simply won’t happen. Consider the following:

1) No boats are allowed through the cut during rush hour. This is the way the existing Ballard Bridge works. If anything, they are likely to extend the period of restriction (

2) The bridge will be taller than the existing Ballard Bridge, which means that very few boats will require an opening.

3) The bridge operator decides when a boat will go through. A boat can be delayed for several minutes.

4) As you mentioned, the Ballard line will be tied to the Rainier Valley line. This means that the maximum headways on the train are six minutes.

Thus the maximum train headway on this line will be six minutes. However, when the boats are going through (outside of rush hour) it is quite likely it will be longer. But just for the sake of argument, let’s assume that trains run northbound and southbound over the ship canal every six minutes.

If the trains are timed to meet at the bridge, then there would be six minute gaps where the bridge could open. If the trains are timed to the opposite extreme, than there will be a three minute gap. Most likely, there will be something off center, such as a 4 minute gap, followed by a 2 minute gap, followed by a four minute gap, etc.

But again, let’s assume the worst. Let’s assume that the trains are running at the worst possible headways and timed in the worst possible way. That means that there will be three minutes for a ship to get through the bridge opening. No problem! Seriously — three minutes is really no problem. The boat will be gone and the bridge closed before the train leaves the Ballard or Interbay Station. It is far more likely that a stubborn rider will keep the door open (and thus delay the train) than a boat ever will.

There are also advantages to an above ground system:

1) It is likely cheaper. It should be obvious to anyone who looks at Link that there are some very serious flaws, due mostly to funding concerns. Not only are some stations “awful” but some stations are simply missing. There is no First Hill Station, nor is there a station at 520. The latter could be dealt with (via dedicated ramps, a tunnel or an additional bridge) but at this point, there simply is no money for it. As a result, riders spend lots of extra time just trying to get on the train. There are also maintenance issues which have caused outages even with such a young system. In short, spending money building a bridge for a rare, if non-existent situation is crazy given the obvious improvements that could save riders way more time.

2) An elevated line would likely result in a better station. The UW station is deep underground. Very deep. This means that every rider spends a huge amount of time getting to the platform, or getting back from it. A Ballard station (and an Interbay one) would likely suffer the same fate if a tunnel is built. This would mean that every rider would be forced to spend an extra minute or two getting to or from the train. All so that we can avoid delaying by a few seconds one train a month (if that).

3) An above ground ride would be a lot more fun. I’m all for practicality over aesthetics, but I also think that transit riders deserve a premium service. Why should someone in a car get to enjoy one of the prettiest views in the world, while someone taking transit is stuck underground? Fairness aside, better aesthetics mean higher ridership, and higher ridership means better fare recovery. If painting the trains purple would increase ridership 10%, then by all means, buy some purple paint. In this case, you don’t have to pay extra — you actually save money by providing a nicer service.

Trade-offs with a system like ours are inevitable. We only have so much money, and tunnels are expensive. Let’s build them where they are really needed — where they would actually make trips faster, not slower.


I think the biggest question about a bridge is whether it will make it harder or easier to extend the Ballard line. I think it’s pretty likely we will someday want to extend the Ballard line north and possibly east.

With a tunnel, we have the expensive, but non-disruptive option of simply digging more tunnel. With an elevated line there is the question of whether we will be able to get the necessary right of way.

The biggest drawback of a tunnel is that it would probably take much longer to build and set the project back even further.


I think it is pretty much a given that this will be extended north. The cheapest way to do that would be to build above ground. Therefore, building a bridge (along with an above ground station at Market) increases the chance that this will be extended farther north. It might even be extended as part of ST3, if construction comes in under budget (or we raise more tax money in the city, or we get more grant money). All of that seems quite plausible if we build a (cheap) bridge, but not at all likely if we build a tunnel.

You also have the politics of this and the West Seattle project. If they put this underground, then West Seattle will want the same. If anything, West Seattle has a much stronger argument for underground. The train is slated to run through the charming cultural heart of West Seattle, while it will run above the ugly, existing car sewer that is 15th NW. Demanding that another tunnel under the ship canal be built would likely cause both projects to be delayed for years, while further extensions (or other improvements to the system) would wait.

Making the east-west connection is a different matter. That is probably the only argument for making a tunnel. An east-west line would involve a tunnel through Phinney Ridge. At that point, there are a couple choices. It could run on the surface through Market, but with all the traffic there, it probably wouldn’t. It would probably run underground. This seems like a great place for cut and cover, as it is fairly flat all the way to 24th (the likely terminus). A transfer from a shallow underground station to a deep underground station would likely be shorter than the transfer from a shallow underground station and an above ground station. So that is an argument for making this underground.

Still not a strong enough argument to warrant the additional cost (and trade-offs) with a deep bore tunnel. It would make train to train transfers easier, but it would also make getting from the surface to a stop worse. More importantly, it would make an east-west subway (along with lots of other projects) less likely because it would cost a lot more money.


>> With a tunnel, we have the expensive, but non-disruptive option of simply digging more tunnel.

Tunnels are disruptive too. Cut and cover is very disruptive, and a bored tunnel needs a place to actually put the boring machine. Every station is also disruptive (most are built by digging down). My guess is that digging and above ground are about the same in terms of disruption, while surface is the least.

Your point about flexibility is a good one, though. Cut and cover, elevated or surface will all follow the street grid. In this case, though, I think that is fine. Serving Old Ballard would be great, but that makes it harder for some, and easier for others. There is a lot of development (of both housing and office space) close to 15th and Market, making it a solid choice. It really isn’t that far to the cultural center of things, either. North of there, I think you want to stay on 15th, since that is where Ballard High School is. You could curve over to 85th and 24th, which would give you a stop on 24th (which would be really nice) but that puts your north-south line very far to the west (a long ways from Greenwood, for example). In short, I think even if this was underground, it would be on 15th, just as the underground line follows the main corridor from 45th to 65th.

If this does go farther than 85th, then it might end up eventually going underground, but doing so would still likely be cheaper if it did that farther north (e. g. Northgate Way). The longer it stays above ground, the more money we save, which means the more money we have to spend on other (arguably more important) things.

Keep in mind, I am quick to point out the times that ST was too cheap. The line from downtown to the UW is an abomination. There should be at least one more station between there, if not three (First Hill, Madison and 23rd, SR 520). But at the end of the day, running elevated is nothing like that. You end up with very similar stations, and a perfectly good system, as long as you do everything else right.


I agree with catphive – I think the biggest argument in favor of a tunnel isn’t the actual crossing, but the flexibility it provides for extensions, especially if there is a Y-junction for a Ballard-UW line. It also allows for stations to deviate a few blocks from 15th Ave, closer to the natural center of neighborhoods. Going with an elevated alignment all but guarantees a 15th Ave/Holman extension alignment … that’s fine, but it doesn’t have any flexibility.
That said, it won’t be disastrous to build a bridge, and I do think to cost savings will be significant if it allows ST to run effectively “at-grade” in Interbay. I also wholeheartedly agree with Ross on #3 – the elevated lines do make for a much more enjoyable ride.