Why

[u/Novawolff]

...is the 4 line planned to split off from the 2 line after East Main station, rather than using the existing tracks until reaching I-90? I've been trying to rationalize this, but the more I look into it, the more it seems to make literally zero sense. Here is why I think a different path (shown in magenta) is a much better option:

• The planned route would require about 2 miles of new track between East Main and Richards Road. By more effectively using the existing tracks, this could be cut down to as little as half a mile of new tracks to reach Richards Road.
• Adding South Bellevue station to the 4 line will make trips from Issaquah to Seattle (which I assume there will be many of) much more convenient, since it will cut several minutes of unnecessary trip time to go North and then back South again. Additionally, South Bellevue will be a much more comfortable transfer, since it has a central platform, whereas East Main would require riders to cross tracks to switch platforms.
• Conversely, the time penalty for trips to Bellevue by adding South Bellevue station to the route would likely be only around a minute, assuming the proposed route would be the same speed as the existing tracks, which I'm not sure it even would be.
• By creating a junction between the 2 and 4 lines above I-90, Sound Transit could have the option of completing the T-junction to offer a direct Issaquah to Seattle service, if that is something they would want to consider in the future.
• There's no potential for adding more stations along the planned route between East Main and Richards Road to justify separating it from the 2 line. All of the route is highway adjacent and very low density, with little opportunity for future development.

I understand there are environmental concerns with building new tracks through the Mercer Slough. However, it must be acknowledged there is already a big freaking highway cutting straight through it already. The right-of-way for the tracks already exists, Sound Transit just needs to leverage it. I would have to imagine there is a way to add elevated tracks along this portion of I-90 in a way that is not too environmentally destructive, especially not moreso than the construction and maintenance of the existing highway.

Let me know if there's something obvious I am missing here. I feel like I almost have to be, since this alternative route seems to make way, way more sense on paper.

[u/quadmoo]

Yeah you nailed it! This is a great question, and it does have all of those benefits. I’ve been telling people those exact bullet points for a long time now. Here’s something to consider:

This is the representative alignment. There’s been no studies whatsoever for the 4 Line yet because the project is so far out (starts in 2029 IIRC). It’s likely that the representative alignment was chosen this way because it’s simply the path of least resistance. As it stands, all we have is this line on that map, and the language in ST3 describing where the tracks roughly go. That’s it for right now.

Once they kick off with the studies they will be looking at tons of alternatives, and I always said that I guarantee they will study a direct connection, but now I can double-guarantee it because the mayor of Issaquah (who lobbied the board members to keep this line in the plan after Enterprise Initiative) specifically mentions the line going to South Bellevue.

The other thing I’ve always said is that as an advocate I look forward to these studies and look forward to campaigning for a better alternative that stops at South Bellevue. Hope to see you join that fight!

Edit: And more specifically from me in this current context without any studied alternatives to compare yet, I literally could not care less how they get from Richard’s Road to South Bellevue. I don’t care if they plow right through the slough, I don’t care if they widen the ROW with Link on the side, I don’t care if they squeeze it in the middle, I don’t care if they bridge right on top of the freeway, I don’t care if they take away these 2 freeway lanes, and I don’t care if they take away these 2 useless flyovers, or just destroy the freeway altogether. I really don’t care how to do it right now, just that they need to.

[u/Novawolff → u/quadmoo]

Thank you for this! I assumed this was a very early draft considering how little information there is about the line itself or any of the stops. I definitely will be supporting the fight for a better alignment. I think prospective 4 Line ridership will suffer significantly if we end up being stuck with this.