As I apparently haven’t posted about the Viaduct since May 12th, I guess it’s time for an update!

Some have suggested that the tunnel could be used later for a new transit corridor. I want to explain why that’s so unlikely – and it’s a simple explanation.

The viaduct deep bore tunnel would run from 60 to 200 feet underground. The points where it’s deepest are also where we need transit – under the center of downtown, where the endpoints of all the potential transit trips in such a tunnel would be. Unfortunately, these would also be where station platforms and entrances would be most expensive to construct.

More after the jump…

Given the cost of similar deep stations, such as Beacon Hill, Washington Park in Portland, and the projected costs for First Hill, building five or six stations to connect to the deep bore tunnel would probably cost more than building an entirely new shallow tunnel instead.

For Capitol Hill, for instance, the route has quite an s-curve before downtown. This is in part because it’s cheaper to make the tunnel longer, giving the trains more distance to climb, than to build a deeper station.

There’s also an issue of grade. Stations need to be relatively flat, but much of the tunnel is not, severely restricting where stations could be. Mitigating this would, again, cost a lot of money.

Finally, capacity. Westlake, University Street, International District, these all need high capacity entrances and exits. With a deep station, most (if not all) users would be entering the station by elevator. The four elevators at Beacon Hill probably wouldn’t have the capacity to handle the long-term needs of the downtown core. Again, more money for a larger excavation – and a lot more real estate cost.

Suffice it to say, a viaduct tunnel will never be usable for transit.

94 Replies to “The Deep Bore Couldn’t Be Rail Later”

  1. I guess could be used for public transit *through* downtown, but i’m not sure how that would be in any way useful.

    1. I dunno, West Seattle to the UDistrict and/or Northgate perhaps?

      There is NO reason or excuse to build the proposed Deep Bore tunnel.

      1. Good tangent. Small point, but how close is the south portal to King Street Station? Transit hubs at both south and north downtown, connecting to I-90 and 520, would be an idea worth keeping as a permanent conceptual balloon.

        Especially if you are a bus rapid transit proponent!


      1. I think the grades are too steep – and there’s no place to put a centrally located station, which is still necessary for HSR.

      2. Although the statement about a centrally located station is completely true, HSR actually climbs and descends steeper grades than standard, because the train has a large amount of momentum to help it continue up a slope, due to it’s higher velocity. The thing one would need to worry about would be the turn radius.

      3. Far between stations, yes. In this case, I suspect because you’d have to have your stations at one end or the other, the chance a train would have to wait for a platform at a grade would put the kibosh on it.

      4. I don’t know about the grades, but it seems like it would work out to have a station at the south end of downtown, near King Street.

      5. A station within walking distance of King Street would have to be on the grade down, where the train probably can’t stop.

    2. Isn’t the deep bore tunnel for rushing cars and trucks *PAST* downtown?

      As such, the rail replacement would be a freight rail, and possibly express passenger train, line designed to rush containers and people *PAST* downtown.

      Perhaps if that were done the Great Northern Tunnel could be converted to local transit….

  2. Fixated.

    That’s what STB is.


    Tilting at windmills doesn’t make for good journalism. Promoting transit doesn’t mean spending most of your waking hours throwing rocks at through roads.

    Greg Nickels, one of the admitted biggest transit advocates we had, knew the importance of maintaining direct through roads. But from you we get, “it promotes the automobile – plus it won’t get used!!” You can’t have it both ways.

    Just get off it and join with us who want to build an awesome transit system.

    1. It’s much more than that. I don’t care if the state builds a tunnel. However, if they do I want the transit and surface improvements that were promised, and if not those I don’t want Seattle to pay for what is clearly the state’s responsibility. I also don’t want Seattle’s limited taxing authority wasted on a state project when they can through money at other parts of the state’s road infrastructure (405, Tacoma HOV, points east, etc.) without batting an eye. But build something in seattle and people from districts that like our money want to shove the cost onto us? Please.

      The people at STB have pointed out problems that need to be addressed before we move forward. The state needs to be honest about the tolling revenues because they’ll be backing bonds. The state needs to be upfront about the cost overruns and the actual costs. The tunnel will most likely cost more than stated and the legislators down south need to come up with the money to pay for it now or jettison the cost overrun provisions.

      Further, we sure can’t bet on the state helping us build quality transit so I’m not so inclined to help the state build its limited access highway under our city.

    2. Why can’t we have it both ways? If tolls significantly limit its use for a while, and then once tolls go away the infrastructure induces demand just like all other transportation infrastructure, don’t we get it both ways? Funnily enough, Ben’s post had it neither way.

      1. Are tolls ever going to go away? I would doubt that the tolls would ever go away. It’s not as if the state will be like “ok, we’ve raised the money we promised now everyone can juts use the tunnel for free.” They will probably just continue to toll the tunnel to raise money for maintenance and so forth.

      2. Actually, that’s covered in state law. Tolling can only exist until the structure’s bonds are paid off.

    3. Michael:

      We can’t build transit to compete with a highway like this. It’s not possible. This tunnel would hamstring future north-south Amtrak planning, future Sounder service, and future HSR, because it would make far fewer people interested in riding the services we have.

      1. Hunh? This makes absolutely no sense. I don’t see how the deep bore tunnel would make fewer people interested in Amtrak, Sounder or HSR.

      2. It offers a cheap, fast way of driving instead. Building this tunnel will lower the apparent cost of driving trips, making it harder for transit to compete – specifically in the corridor where we want to build more transit next.

      3. Give me a break. The DBT doesn’t do anything but replace existing capacity — it doesn’t change the equation between transit and the automobile one bit. Transit is doing fine right now and the DBT won’t change that one bit.

        Now gas prices might, and the move towards more urban living and less commuting certainly will.

      4. Actually, the DBT doubles through capacity. Right now, the through drivers have to contend with people driving only into and out of the city. The DBT would be specifically subsidizing the through trips, which currently make up less than half of its capacity.

        The in/out trips are already pretty easy to serve with transit. The through trips are not – and this makes that much harder.

      5. Correct, which is why the DBT might INCREASE transit demand. The tunnel will not provide easy access to the city center, as there will be no downtown exits or entrances. That makes transit from the neighborhoods into downtown relatively MORE attractive than it is now, because the viaduct currently allows drivers to exit into downtown.

      6. That’s fuzzy math. Commute patterns will change if the DBT is built. This is well understood in regards to road infrastructure. Some people who currently use an intermediate exit will elect to travel through the tunnel and access their destination from there. It’s not as simple as “50% now so 50% then.”

        But the implications of what you wrote in your last paragraph are actually GOOD for transit. Because the DBT doesn’t support commute trips in and out of the downtown core this actually represents an opportunity for transit to pick up additional riders — this is good. And the remaining through trips will have an incentive to change since now they will be required to pay a toll – again good for transit.

      7. lazarus, you’re right that it’s well understood – and we understand that most of the endpoint-downtown trips won’t traverse the tunnel, especially with a toll that already causes 40% diversion.

        It’s hardly good for transit to create a new highway to subsidize trips that are the trips *hardest* to serve with transit already.

      8. Ben,

        It’s not a “new highway.” It’s a replacement to an existing highway. It’s a completely different thing.

        The overall functionality of the highway as a DBT hardly changes — except that trips terminating in DT are less well served and pass-through trips will now be paying a toll. Both of these are good for transit.

      9. Yes, Ben… you are a thoughtful guy and have a wealth of facts to draw on. Please stop the shotgun replies to every post that threatens your views and concentrate via Posts or comments with a little more substance. I’ve read this several times (the news read real slow) and it keeps coming across as “the tunnel’s so good it will destroy the chances of forcing people onto transit.” I know that’s not what you meant and maybe I’m missing the (sarcasm) (/sarcasm) tags?

      10. It’s not “good”. The tunnel’s such a subsidy to driving that it will destroy future chances to build transit.

      11. This is absolutely not true.

        Stop the war on the car — transit will do just fine even with the DBT.

      12. It may not destroy our chances in building more transit in the way Ben is describing but it will certainly harm Seattle’s chances of financing more transit.

      13. Seattle isn’t paying for the tunnel — the State is. Nor will Seattle be covering cost overruns.

        And the surface and seawall improvements will cost the same no matter what happens to the viaduct. McGinn is just plain wrong when he talks about tunnel financing (and I think he knows this but intentionally refuses to acknowledge it).

      14. Nor will Seattle be covering cost overruns.

        That’s an interesting faith-based statement. You may be right, state law says otherwise.

        The surface street improvements could be paid for with State gas tax money if it wasn’t all being consumed by the tunnel.

      15. It’s not a faith based statement, it’s just not going to happen. Even most state lawmakers acknowledge this. And a lot of that language isn’t signed by the city anyhow.

      16. This isn’t about money, as I’ve explained in several places now. It’s about demand. Transit projects have to meet much more strict guidelines for demand and potential ridership than road projects do (obviously, as nobody’s batted an eyelash at a 40% drop in projections due to tolling).

        The issue is that a future rail line’s potential ridership is going to look much lower after this is built – so that future rail line will be less competitive for FTA funds, less cost effective, and easier for the opposition to fight.

        Transit proponents *must* understand that the *only* reason we don’t have good transit in the US is because we keep building roads.

      17. So you have no one committed to picking up the tab for overruns. That sounds like a recipe for success.

      18. Tunnel supporters can’t have it both ways.

        They can’t argue that the tunnel is a “done deal” because everyone has voted on it and appropriate money… but then turn around and say that Seattle is not on the hook for cost overruns, which are a part of that legislative deal.

        And, lazarus, legislators have been very clear that they will not provide more money to Seattle, period. Illegal or not, they will find a way to leave us stuck with the bill. And, at least for the moment, our Senators have absolutely no interest in bringing federal monies into the equation on this.

      19. I don’t like the tunnel, but I completely disagree with you. The tunnel will not negatively affect the ability to expand Link, Sounder, Amtrak, or anything else, partially because it doesn’t link places that people want to go to so hardly anyone will use it.
        I don’t get your reasoning about how it would affect future Amtrak, Sounder, and HSR planning, the only driving trips that it will make faster and easier is if you’re going from like Wallingford to West Seattle. Most people who would ride the future Westside line would be going to Downtown from Ballard or West Seattle, and this will not affect that market; in fact, with the increased surface traffic from the viaduct being taken down, even more people would probably want that light rail line.

      20. These are all “mosts” or “partiallys”. All these trips are mosts or partiallys.

        The tunnel will specifically subsidize through trips – say, from Fremont to the airport, or from Ballard to Shoreline. These trips are the hardest ones to replace with transit already, and with the existence of a fast car option, future transit options won’t appear to compete well and will be much more likely to die in the planning stage.

      21. Ben, that comment is ridiculous on its face.

        First, people have been saying over and over right here that the Tunnel would reduce the number of cars traveling 99. That doesn’t jibe at all with “making it more attractive.” As I said before, you can’t have it both ways.

        Second, I think Seattle has had ample opportunity to prove that pain doesn’t drive transit ridership – convenience does. We’ve made it very painful indeed to get from here to there by car, unless traveling at night. Parking costs more than a meal at some restaurants, and on-street parking is slowly disappearing altogether. An event in Seattle can mean traffic jams backing up to Redmond on 520, to Factoria on 99, to Lake Forest Park and Tukwila on I-5.

        What we need is decent transit. Lay the shame on our parents, who checked “No” on plan after plan, for leaving us this mess. But don’t put the cart before the horse in the name of “saving ourselves” for some magical transit that might show up in 30 years.

        You’re right in one respect – you can’t build a bus service that competes with a road, because as much as you or I might like them (and I do), to most people buses are an awful alternative. Agreed that the only way to force people onto buses is to take away their cars (or roads) completely.

        But that’s not going to happen, because citizens won’t let it happen.

        So let’s get on with building fast transit with a dedicated right-of-way, so the citizens can get from neighborhood to neighborhood with something vaguely resembling speed and comfort, THEN start talking about removing through highways.

      22. If you really think pain doesn’t drive transit ridership, I have a bridge in Kansas to sell you.

        Remember the I-5 construction work that spiked Sounder ridership?

  3. Even if you wanted to build stations there, I don’t think you could, because you couldn’t dig that deep of a station just in the street, you’d have to demolish a few skyscrapers.

    1. The Hong Kong MTR subway system integrates deep-bore station entrances into existing buildings, then uses high speed escalators to move people between street level and the multiple platform levels.

  4. Simply, just don’t build the tunnel!….it will be saved for transit later…and can always convert waterfront into a nice international style avenue with a long narrow park on the site where viaduct is. They just need to rebuild the seawall and all that improvements to the waterfront area. We just don’t need 2 highways running thru the city! I-5 can always be retrofitted to reduce congestion because it’s poorly designed.

    1. How would you retrofit I-5? Put more lanes on top of it (making a slash through Freeway Park)? Widening it (cutting into the hillside or downtown)?

  5. The biggest problem with your argument is that building transit infrastructure and building car infrastructure are antithetical. I mean, we have a limited, captive audience, yes? (Aside from tourists, who, frankly, are never at the center of any of these discussions anyway.) If you want transit, you need more people that will actually use it. Otherwise, what is the point of building it. If you build more car infrastructure, people will use that *instead* of – not *in addition to* – transit, and so it makes any transit that competes with it a tougher sell. Buses are a bit easier because everyone’s in love with buses (especially those who never ride them). But always remember that high speed, high capacity public transit and high speed, individual transit are like Microsoft and Apple: competing for the same user base and just as fervently (and with the same annoying fanboys on either side).

    1. Zelbinian, I think you’ll find my reply to Ben covers this, but as far as “competition”:

      Seeing roads as “competition” for transit is all backwards – and smart planners understand this. But let’s say it IS a competition. Apple doesn’t get new users by sending people to Microsoft to purposely screw up Windows so you can’t run it. They do by making their product better.

      But what you seem to be saying is that our only choice is to make driving worse, so that the buses people have demonstrated they don’t want to ride are by comparison fast and convenient. I disagree.

  6. I can’t recall where I read this some years ago, but it mentioned there is a second railroad tunnel, running under 5th ave from the UP Station (ST). As the story was told, the project was abandoned after getting to about Madison, or so.
    That would be a better place to start looking for parallel rail routes through the city than converting the deep bore. Did I just dream that, or can someone smarter than me confirm it?

    1. Before the DSTT was built there was a big half block wide hole between Jackson and Main next to Fifth Avenue. The north wall below Main looked to me to be solid earth, not an abandoned tunnel heading. I expect that the hole at one time had a stub track to cut locomotives loose and back them out from around trains that arrived in Union Station at odd hours.

      But that’s just observation and speculation, based on no historical knowledge.

  7. I’m simply fantasizing here (seriously), but if we were to build the original cut-and-cover tunnel on Alaskan way with a train level for freight, imagine the possibilities of what could be done with the existing 100 year old tunnel. A quick path to providing some of the most expensive right of ways to a west side rapid transit line could be provided – upgrade the tunnel and build stations @ king street, in Pioneer Square, @ the library, on the diagonal between the Pike Place Market and Benaroya Hall (with entrances at both)- splice off from the existing tunnel there and continue into Belltown under 1st or 2nd. Obviously, there are a million problems with this, but I do wish that the SR99 study would have veered into being a more multi-modal approach. At the end of the day, I think the tunnel is fine, but we are still faced with future problems of increasing freight capacity and finding an affordable pathway for N-S passage of a “west side” rapid transit line. Its too bad that we don’t occasionally look at Seattle’s hour-glass shape as a benefit rather than an obstacle – given our serious deficit in continuous north-south paths through the core, bundling more than one mode in a once in a lifetime project would be nice.

  8. What is getting ignored in Ben’s analysis is a very simple fact- the tunnel, at both ends, connects with a graded and improved ROW the public already owns and uses for transportation- Highway 99. And, strange to say, over the years a lot of people have ended up living or doing business close to 99.

    So if, for example, Mike McGinn were to suggest converting 99 to transit, we would suddenly learn that this is a great idea! Don’t try this at home! You or I, not being possessed of Mighty McGinnlike powers, would be ridiculed for suggesting such a thing.

    However, if it were done, it would not be necessary to build stations downtown. At the south end passengers could transfer to LINK, a probable streetcar or two, or buses. Passengers coming from the north would not spend too much more time riding to the ID or Stadium station (because the train would not be making “5-6” station stops going through town) and transferring. A station at the north end of the tunnel would serve lower QA and South Lake Union.

    In fact, even if your stations were free, the most you would want in addition is one connecting to Westlake Station. There is no need to make every train a local when the streets above are covered with buses.

    While I have no mighty McGinnlike powers, I’m still tempted to a little back-of-the-envelope guessing about the savings of using 99 for rail, instead of building an entirely new rail line. South of Seattle we have the ROW out past the airport, which might cost, say, a half billion to purchase by condemnation from existing owners. Tunneling through Seattle- let’s call that two billion. The high-level bridge over the Ship Canal and out north on 99- easily a billion.

    So, if the tunnel were built, and it then seemed desirable to add another N-S rail line, the choice would be between a Highway 99 alignment, and a new corridor very conservatively estimated to cost $3.5 billion for the ROW, tunneling, and bridges alone.

    It will be interesting to see what happens in the long run.

    1. Catowner,

      Using 99 for transit would be fine, but Ben’s entire point is that the DBT does nothing to advance that cause.

      All your facts about 99 north and south of downtown are totally irrelevant to that argument.

      1. And my two points were (again) a) you don’t need those downtown stations, but, b) if you wanted downtown stations, you could probably afford them if you saved $3 billion on the other costs of construction.

      2. a) you’d never justify a line without downtown stations.

        b) It’s likely EACH station would be $1b. It would be cheaper to start from scratch. That’s the point.

      3. On reflection, you could build about 20 miles of light-rail for about $1 billion. The third runway at Seatac, supposedly the largest earthmoving project in something-or-other, cost less than a billion.

        But who knows, maybe subway stations are just very complicated things that nobody has ever built very many of. Oh, wait

      4. catowner, you can’t seriously be arguing that a 200′ deep downtown station is somehow cost-comparable to a 50′ deep London Underground station built a hundred years ago.

    2. You do need downtown stations. A lot of people won’t ride if they have to transfer at all, and this would make the one-seat ride impossible for a lot of downtown.
      A 99 rail line would be good far in the future but the Ballard-West Seattle Line would have much higher ridership and is a much more important link.

      1. catowner – you know that’s not what he’s saying. This is starting to look like trolling.

      2. Well, excuse me for living. I never had a job in Manhattan that I didn’t transfer trains to get to, and I never had a job in Seattle that I didn’t transfer buses to get to. But I will admit I obviously am not one of the people who “won’t ride”.

      3. The fact that you’re trying to compare transfers to get into downtown *at all* (where we have this whole post about how southbound transfers at Montlake would cause crush loads already) to transfers in Manhattan just points out how misleading you’re being.

      4. NYC subways make several downtown stops. So does the PATH train, sort of. The suburban railroads make only one downtown stop, but that’s akin to Sounder.

      5. Trying to cater to everyone that demands a one seat ride within a few hundred feet of their destinations isn’t a realistic public transportation goal. This isn’t like an airline where you’re afraid they’re going to lose you luggage. People don’t want to transfer if the transfer is inconvenient and layover times are long. Building a system that blankets high density areas with properly interconnecting routes is a much better approach than trying to anticipate everyone’s origin and destination and creating individual routes. That approach is what makes transfers such a PITA.

      6. I think you’re missing his point. We’d never, ever, ever, ever get a dime of FTA money for a line that skipped our employment core.

    3. Cat Owner,

      The Aurora Bridge was not built to support a fixed guideway. You’d have to replace it and there’s your billion.

      You could turn the middle lanes of 99 into a busway for BRT “trains” (three or four unit articulated ETB’s) if they didn’t have to mix with traffic.

      Not advocating; just sayin’.

      1. Sounds like a definite deal-killer- if true. What exactly are the challenges in supporting fixed guideway? I understand that the bridge may be load-limited to something like 25 tons for trucks, but how that translates into axle-loading for trains is a little beyond me.

  9. If I were king I would tear it down and if after transit improvements and a few years we find that we really need a bypass tunnel (and the economy turns around) then we can build a tunnel.

  10. I’ll have to step in and say that the Deep Bore Tunnel will never restrict usage of Sounder, Amtrak, or BNSF, or any future HSR for that matter. The only way that will happen is if the tunnel were to collapse.

    Would HSR take a new route completely? No, it would not, not until it reaches more of a rural location, most likely South of Tacoma. It is cheaper and smarter to use an existing ROW (as Cal HSR is finding out)

    Can one build a Higher Speed Corridor in the existing ROW? Certainly. Is the DBT going to affect it? No, it won’t.

    People will drive when it works out best for them and people will take transit (bus, rail, etc) when it works for them. As some one who does drive and needs a car, I am definitely one of those whom drives when needed and bus/rail when I need to.

    One final note, while I don’t like the idea of the DBT and tolling because it will result in more traffic on the Alaskan Way Viaduct, it should be kept in mind that there is a new on/off ramp that will be built at Atlantic Street. While this is not “central” Downtown, this is an alternative to 4th and Spokane Street.

    And actually.. one last thing…

    Who would ever want to have transit, in any form besides a through route in the DBT? I for one would most certainly not, nor would it be safe to have it. Its designed to be a bypass of Downtown Seattle, without the interruption of traffic merging at different points.

    With all of that said, do I support the tunnel? No, not at all. I rather see that money go towards improving schools and improving I-5 through Downtown Seattle to ease the consistent congestion in that area. I’d also like to see the funding go towards improving rail for the Cascades and light-rail to West Seattle and Ballard. It is a done deal and there isn’t anything anyone can do about it because try to delay the project. (Sounds like a McGinn speech doesn’t it?) but if I was the DOT, I have my priorities in other parts of the state as well but that, is for a different post.

    1. I’m not saying it would have any physical impact. I’m saying that future rail planning wouldn’t project as good of ridership because of the new bypass.

      1. Future rail would actually project a better ridership precisely because the bypass doesn’t serve DT Seattle (which is the largest concentration of jobs in the state).

        For pass-through demand there is no change.

      2. You’re making that up, and it’s wrong.

        A surface option would make downtown trips slower than the tunnel option. Rail projections would be higher with a surface option than with the tunnel option.

        Furthermore, you’re completely ignoring the examples I’m pointing out. Fremont to Airport? West Seattle to Shoreline? Both of these are tunnel trips, but with a surface option, it’s likely that a good rail to rail transfer would be competitive. With the tunnel, they would not be. How are you missing this?

      3. And there will probably never be transit that goes through downtown without stopping. I can’t think of any other place that does this, just like I can’t think of any place that has metro stops on the edge of downtown but not inside. The number of people going to downtown or going elsewhere dwarfs the number of people going from the north end to the south end or vice-versa. 99 has always been the best bypass for them (if they’re local — long distance drivers would have to go on Northgate Way or such to get to 99). While I’m not in favor of the tunnel, the odds of getting an express transit route through downtown are slim with or without the tunnel. All the other travelers — the ones going to downtown or going other places — are really a separate market. The tunnel won’t help them, and it won’t decrease their demand for transit. But granted that the tunnel would put a squeeze on other funding sources.

      4. Oh, we don’t want express. Adding four minutes to the trip stopping downtown isn’t really the issue. The issue is whether that’s more reliable than driving – and with the tunnel, driving reliability will go up too much.

        And yeah, that’s a bad thing.

      5. Trying to make transit look good by deliberately sabotaging roads is a bad thing. Trains are never going to get people everywhere and surface transit is going to be hurt worse than the evil automobile and truck freight you’d like to stick it to. Individual drivers can vary there route and time to avoid the worse backups. Surface transit can’t and it will be further impacted whenever it has to merge back into traffic.

        Soon the congestion will reach a point where people don’t want to shop or go to shows downtown. Businesses will move to places with better mobility and Seattle will lose both tax revenue and see reduced demand (potential ridership).

      6. Not providing a multi-billion-dollar roadway when state law says we have to reduce our VMT is hardly sabotage.

  11. Does the Deep Bore Tunnel make it harder to eventually build a subway under Second Ave or First Ave to provide the capacity for a West Seattle – Downtown – Belltown – Seattle Center – Ballard LRT route? Will the be room to fit that subway above the new road tunnel?

    1. Hard to say for sure, but the more tunnels there are, the more you have to get creative to make sure they avoid each other.

    2. This is a good question. The proposed route apparently tracks First Avenue in order to stay west of the DSTT. It passes under a sewer line and the BNSF tunnel around University or Union. That would certainly seem to rule a First Avenue subway out, but then one probably wouldn’t want to put a subway under First anyway. It’s too far from the centroid of destinations around Third and Fourth.

      Things would probably be pretty crowded around Pine or Stewart where it deviates to the east and would cross the future path of a Second Avenue subway tunnel.

    3. Except for near the portals there shouldn’t be a real problem with conflicts between the Deep Bore Tunnel and any transit tunnels. The Deep Bore Tunnel is, well, deep. Any transit tunnel will be closer to the surface.

  12. Whoa!! Seems like everyone is getting lathered up over nothing.
    The DSTT is a long way from being ‘maxed out’ for LRT only operations.
    Calcary projects 2 min minimum headways. The FTA’s latest analysis of shows minumum headways of 102 seconds (w/ moving blocks and VSD), for 45 sec station dwell times.
    Not that DSTT would ever see 2 min. headways, IN THEORY, multiply 4 car trains, with 200 per car for 16 hr./day gives about 3/4 Mil. daily riders.
    Link currently carries about 2% of that, so there’s a huge reserve of capacity in the current tunnel, and why not keep transfers to the same tubes.
    Trains from W. Seattle could merge along E3, and Ballard trains could split off to CPS, turning Northwest through Seattle Center.

    1. The problem is the Northgate to Downtown segment. The plan is to have 4 car trains every 2.5 minutes during peak hours. There isn’t a lot of additional capacity left to put another North of downtown line in the DSTT.

      1. Chris and Ben. This thread is about done, so I won’t belabor the point I was making, except to say this would be an interesting thread by itself sometime in the future.
        Link to Northgate is approved and will be built. Extensions north will happen. That said, ridership will be the determining factor when deciding frequency of trains and size of consists. The DSTT has an enormous capacity for riders when the buses leave it. That capacity should be fully utilized to the best advantage in moving riders through the system.
        I look forward to more interesting discussions… someday.

    2. The DSTT will eventually run 2 minute headways – that’s in the Sound Transit long range plan. You really can’t wedge more service in there reliably.

  13. You have to provide emergency egress from then DBT at a few points through Downtown. You also need ventilation.

    So, it’s not like there will be no access built between the tunnel and Downtown.

    The question really is what would it cost to incorporate transit stops inside the tunnel, and to add high-capacity elevators at those points.

    If we are going to build the DBT, what would it cost to make this tunnel usable for transit (probably bus) connections to Downtown. In particular, would it increase transit use by maintaing Downtown transit connections while eliminating vehicle connections?

    1. Emergency egress will most likely be a parallel escape tunnel. 200′ flights of stairs certainly wouldn’t cut it. Elevators aren’t practical because of cost and the likelyhood that in an emergency the power might be out. I would except the same arrangement as if this were going under a body of water. Ventilation can be provided by a pressure differential from one end to the other.

    2. Michael, there are no emergency access or ventilation points that I’m aware of planned for downtown. If you can show me where these are on a plan, please do, but I have not seen any plan for them. You can meet both requirements with chambers in the tunnel itself.

    3. It may be easy enough to leave space for future elevators and stations. I don’t know how much that would enlarge the tunnel cavity or add to the expense, but it might be doable.

      But even if it’s possible to convert the tunnel to transit later, it’s another question whether it’ll be feasable. You’d have to move all cars out of the tunnel, unless the trains were only going to take one lane each direction. In the brave new future, car usage may dwindle to one lane’s worth, but it won’t dwindle to zero. There would still be some remaining cars the government would have to forcibly eject from the tunnel — and that would be a big political fight. Unless, maybe 30 years out, I-5 traffic has shrunk so much that all cars could be moved to it without slowing anybody down.

      One nice thing about a 2nd Avenue transit tunnel is there’d be a perfect transfer point at University Street where there’s already a 2nd Avenue entrance.

  14. I want to address the claim that those of us who oppose the deep bore tunnel are “sabotaging” roads and car-based transit.

    You want to talk sabotage?

    The sabotage already took place, and it was subsidized freeways and cars that did it. I’d like to undo the decades of car-culture sabotage that has wrecked the environment, cities, the countryside, and our health.

    We simply should not dedicate our limited resources to massive new projects that continue a failed policy.

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