Link in Tukwila: An impressive way to build elevated trackway

Last post, I mentioned seeing a huge steel framework perched atop the support columns for what will be Tukwila Station and the associated track headed north. Owned by PCL Construction Services, it hoists about ten trackway segments at a time between sets of support columns so they can be put into place. PCL's web site has images of what the trackway they're contracted to build will eventually look like, but what I'm more impressed by is what it looks like now - with the first trackway section erected this week.

Tukwila will be the southernmost stop in the initial plan, with Airport Link (and its excessively amusing "Kiss and Ride") to follow six months later. As far as I'm concerned, though, this is the most impressive segment - sharing right-of-way with I-5 and SR-518, it's highly visible to many of the people who will use it.

This brings me to some new speculation: What's quite effective as a local service on MLK for South Seattle is not particularly desirable as part of an express service to the airport and further south. Let's look back at that initial plan. Headed south from downtown, Link turns east through Beacon Hill, and meanders along with an eventual return to the Duwamish River valley. I can understand that for a first segment, serving as much local population as possible is key, but as a regional system, eventually we'll want to offer service that doesn't stop everywhere (and isn't limited to streetcar speeds) for people going between major destinations.

So, perhaps, there's an option opened up by the valley. An express link could bypass the Rainier Valley, continuing straight where the trackway turns to go under Beacon Hill, and reconnecting before the Duwamish River crossing - perhaps using 4th Ave and Marginal Way. Local service could extend from Ballard (note that rail link on the long-range plan map) through downtown to MLK, then rejoin the main line in Tukwila. Express service would come in from north of Seattle, bypass MLK (perhaps with one or two stops near Boeing Field) and continue south.

You wouldn't have to call these local and express. They could be "Blue" and "Green", or they could have local unique names like "Duwamish" or "Walla Walla". I do see some problems with this, of course: the expected multimodal station at Boeing Field would only be accessible by one line, confusing some passengers - but someone starting in Seattle wouldn't need to transfer there, and someone at Sea-Tac would simply take the local (MLK) train. By the time this happened, we'd probably have 3 minute headways all day, so it wouldn't be a significant addition to travel time.

But those are the rantings of a mad transit advocate. Japan does this between Narita Airport and Tokyo - there are several train types: some continue beyond Tokyo Station, some serve communities between the airport and downtown. Interestingly, as soon as Airport Link is completed, we will have more frequent service and lower travel time between our international airport and downtown than Tokyo does to Narita - at significantly lower cost.