At its meeting of July 25, 2013, the Sound Transit Board approved a pair of contracts for engineering studies to design a turn-back track at International District Station (IDS) for East Link trains going in and out of service at the SODO Operations & Maintenance Facility (O&MF).

The background for the engineering study contracts state:

An interdisciplinary Sound Transit team agreed that a turn-back track facility along the Central Link alignment would improve train movements between East Link and the OMF. These improvements include the ability to add or remove light rail vehicles for early morning start up and peak period demand as well as the ability to accommodate a disabled train. Various options were evaluated for cost, construction impacts, service impacts, and operational efficiency. The option of a turn-back track facility at IDS was selected.

Sound Transit staff declined to elaborate on whether a turn-back track at one of the other stations was considered as part of this process.

Since the contracts were merely for engineering studies, and much larger construction contracts have yet to be approved for this work, there is still time to take a look at the alternatives that allow for a center platform at IDS instead, and put the turn-back track(s) in Pioneer Square Station (PSS), University Street Station (USS), or Westlake Station (WS).

Another group of options would be to have a crossover track from the northbound platform of one or more of these stations to the southbound exit at that station. That is to say, East Link trains going out of service would pull up along the platform, and then turn back along a crossover track at the south end of the station splitting from the northbound track about 20-30 feet north of the south end of the station, merging with the southbound track a few feet north of the south end of the station. In order to avoid tracks crossing over each other, no station could simultaneously have both a center turn-back track and a crossover track.

It bears repeating that the center platform option we’ve been talking about in IDS is to add a center platform, not to remove the outer platforms, which would enable use of all 32 train doors while at IDS, in a variation of the “Spanish Solution” (in which passengers enter the train on one side and exit to a separate platform on the other).

In the comparison and analysis below, I will focus on the following aspects: operational safety, operational cost, construction cost, trip time, and peak operational throughput.

Safety is Job One

Let me start out by saying I am no expert on these issues and have no professional credentials related to the topic. But I do have a degree in Mathematics.

One benefit of having a turn-back track in PSS, USS, or WS compared to IDS is the ability to get the big picture and minimize opportunities for derailments.

In the IDS turn-back track plan, there is a merge switch between East Link trains headed north and South Link trains headed north. There is a split switch for North Link trains to head either south or east. North of the merge, there is a split switch for northbound trains to shift onto the turnback track.  There is a similar switch for trains turning back to merge with the southbound trains north of the southbound split.  There is also a switch right in the middle where the northbound trains turning back merge, change direction, and then split to the track that gets them going southbound. The turn-back increases the number of switches station supervisors have to pay close attention to from two to five. On top of that, consider where the northbound split switch is proposed to be located: a mere several yards north of the northbound merge switch. Then, before the train turns back, two or three switches have to be flipped (depending on whether the train will then proceed east or south), all within close proximity. This should give some railroad safety experts at least a tinge of angst.

IDS turn-back track proposed by ST staff. Note that the turn-back track is right between the platforms in IDS, is barely long enough for four-car trains, and would have a similar design if built at Pioneer Square Station, with a few additional feet to spare. (Click to Enlarge)

Moreover, the person in charge of the switches is responsible for the orientation of all five switches. If, instead, a center platform were built in IDS, there would only be two switches in the area south of the station, and they would not need to be coordinated with each other.

A turn-back track in PSS, USS, or WS would involve three switches, all coordinated with each other. A crossover track in one of these locations would involve only two switches.

So, you must be wondering which station has the longest distance to allow the greatest stopping distance for a train turning back. That would actually be University Street Station. The other stations, including IDS, are nearly identical in length, but about 20 feet shorter than USS. PSS has a few more feet than IDS in the crucial central area between the platforms.  But then, you must be wondering why the area south of IDS isn’t being used to lengthen the turn-back track. Maybe it could be, but the diagram shown (above) to the ST Board shows that the switches will be at the entrance to the station.

In short, staff has made no clear case that the turn-back track is safer at IDS, and there are reasons to believe it is actually the most dangerous option.

Operational Cost – Much Ado About Almost Nothing

One of the reasons for placing the turn-back track in IDS is to minimize deadhead time for East Link trains going into and out of service at the SODO O&MF. So, let’s calculate the rough daily operational savings of having it there compared to having it in the middle of Pioneer Square Station.

Just to have an apples-to-apples model, lets assume each line (Everett-to-Redmond and Everett-to-Tacoma) is a 4-hour round trip for a given train, including layover time. (If it is longer or shorter, that won’t alter how the two options compare.) Let’s assume ten-minute off-peak headway and six-minute peak headway on East Link and South Link. Let’s also assume half of the trains stay at the SODO O&MF, and the other half are split among south, east, and north O&MFs.

To maintain 10-minute headway on the Everett/Redmond line, 24 trains would be required. Add a similar 24 trains on the Everett/Tacoma line, for a total of 48 off-peak trains. Decreasing headway to 6 minutes would increase the fleet requirement to 40 trains on each line, or a total of 80 trains. After morning peak, 32 trains would be brought out of service and later returned to service. This makes a total of 224 goings into service and comings out of service in a typical weekday. Approximately 112 would be to/from the SODO OM&F. Let’s further assume those trains at SODO are being distributed equally, with one half headed north or coming from the north, a quarter headed or coming from the south, and a quarter headed or coming from the east. That leaves approximately 33 times a day the turn-back track would be used. Ideally, it should be even less, as it makes more sense to add and subtract trains at the end of a line in order to control headway, but let’s go with 33. Having to go an extra station to PSS, and come back that same extra length, would add approximately four minutes under the current joint-operations speed limit, but will be less when joint operations cease, but let’s go with four minutes to be sporting.

Do the math, and we get two hours and twelve minutes that might be saved each day by putting the turn-back track in IDS instead of PSS.

But wait. We still have to calculate the cost of longer dwell times at IDS due to not implementing our proposed variant on the Spanish Solution. It should be plainly obvious that using 32 doors on every train instead of 16 will reduce dwell time. The question is by how much would that dwell time need to be reduced, on average, to overtake the deadhead savings. To get that number, we need a count on the number of in-service trains passing through IDS on a typical day. I’ll skip the details and tell you that, based on current peak, off-peak, and 15-minute headway periods, it would come out to 544 daily stops in IDS, or so. At 7 seconds of extra dwell time per stop in IDS, the deadhead savings gets erased.

On top of that, if the extra dwell time pushes operations to have one more train in service during either peak or off-peak in order to maintain headway, the additional platform hours for that train overwhelms the paltry savings on deadhead.

Construction cost

The cost of building the turn-back track should be virtually identical regardless of where it is built. The only additional cost to build it further north would be more money for engineering, similar in amount to the $955,000 in contracts the ST Board approved for engineering the turn-back at IDS.

The cost of building a center platform at IDS should be the cost of pouring concrete and installing the textured strips, plus adding an emergency elevator at either end (to comply with ADA). Design and engineering would be involved, of course.

Passenger Convenience & Trip Time

Passengers transferring between the east and south routes will spend a couple extra minutes getting up to street level and descending again, instead of stepping off the train, walking a few steps westward, and stepping onto the next train going the direction they want.

As the system grows, this transfer nuisance will impact close to one-sixth of all destination pairings in the system. Another third will be impacted by longer dwell times at IDS. The remaining half will be indirectly impacted during peak by increased minimum headway…

Peak Train Throughput Capacity

This is where the decision to place the turn-back track in the middle of IDS turns from safety cheap-out, minor daily operational waste, and down-prioritization of passenger convenience, into a major design flaw. IDS will probably be the busiest station in the system, due to east/south transfers. If it is, it will be the bottleneck that will dictate minimum headway. Any increase in peak dwell time at IDS will increase minimum peak headway on North Link by the same amount, and will increase minimum peak headway on East Link and South Link by twice that amount. This will affect the number of trains that can get through the tunnel during peak of peak. Add to that the time trains will spend sitting and waiting for the go-ahead signal to merge coming into the station, and the dream of 3-minute peak headway on North Link, 6-minute headway on East Link, and 6-minute headway on South Link may have just gone up in smoke.

If ST Staff has more reasons not to build a center platform at IDS, I hope they will offer them to the public. If there aren’t more reasons than already publicly presented, then the lack of a center platform at IDS may be the biggest design blunder in the history of the Link system.

It should be pointed out that this design flaw is not in how the stations were built in the first place. Indeed, the extra space in the middle of each station is what is enabling the options for where to build a center platform. One of the ST Board members tried to blame the Board’s decision to move forward with building a turn-back track instead of a platform in the middle of IDS on elected officials lacking foresight 20 years ago. No, the design flaw is how the stations are being rebuilt, and so totally on the shoulders of the current ST Board, if the Board opts to proceed with construction of the flawed design.

This blunder can be fixed now, at minimal cost, and in plenty of time for the 2019 tunnel closure and conversion to rail-only operation.

50 Replies to “The Costs of Not Building the Turn-Back Track in a Tunnel Station Further North”

  1. Brilliant Analysis.
    Unfortunately, I think the ship has sailed away on this improvement too, like so many other ‘cuts by a 1,000 deaths’ my hero alludes to.
    My fear has always centered on Seattle spending more than anyone else on a rapid transit system ($$/mi or $$/pax), but ends up with one segment that works really well from Northgate to Sodo, and a bunch of other marginal crap that is barely better than the buses it replaced.
    All this cost is at the expense of our backbone bus systems that whither on the vine, as the tax fairies are getting weary of trying to plaster pigs with lipstick.

    1. Geeze I love an edit feature so I don’t look so stupid some days – ‘death by a 1,000 cuts’ – yeesh

      1. Actually, I kind of like “cuts by a thousand deaths”. I’ll have to remember that.

        As to the substance of your argument, I completely agree.

    2. We should probably turn that tunneling machine south after finishing Northgate and redo Seattle to SeaTac as a subway.

      While we’re at it, I still get the willies about running LINK on a floating bridge.

      Can we tunnel Lake Washington while we’re at it. Expensive as they are, we do tunnels well. And better something expensive and worth it, then something expensive and bad.

      1. Like a tunnel between Magnuson Park and Kirkland under Lake Washington on a Ballard/Kirkland line?

  2. Excellent article… I really hope that a center platform can be realized at IDS. One question- if they did this planned turnback at IDS, where would the final stop be for deadheading East Link trains? Seems that it’d make a lot of sense from a rider perspective to have the final stop at the main transfer point.

    1. That’s another good reason for a PSS or USS turnback (if there is room for one)… the final stop would be at Rainier, requiring riders to wait for the next full-route train.

      1. “That’s another good reason for a PSS or USS turnback (if there is room for one)… the final stop would be at Rainier, requiring riders to wait for the next full-route train.”

        I doubt that would be the operational plan if the turn-back is at IDS. Rather, they’ll just have about 16-17 trains deadheading from Redmond at the end of the day.

        There is no guarantee, either, that those trains would be in service if they could drop off at IDS, but at least it would become an option. What would likely happen, though, is that the trains going into service would pick up at IDS, instead of starting in service at Rainier/I-90 Station.

      2. There are both deadhead trains and in-service trains leaving/returning to the OMF in the current Central Link operation. The in-service trains start and stop at Beacon Hill. Especially at the very start and end of the day, I’d expect some of the trains to be in service.

    2. This was my thought exactly. With the center turnback track located at PSS, East Link trains heading out of service could serve IDS instead of Rainier as their final in-service stop, which is vastly more useful. If operationally the last possible in-service stop was Rainier, I could understand ST deciding to deadhead these trains from Redmond. Making it possible to stop at IDS makes revenue service for these trains plausible, and very positive for riders.

  3. The other stations, including IDS, are nearly identical in length, but about 20 feet shorter than USS. PSS has a few more feet than IDS in the crucial central area between the platforms.

    Are you sure about this? IDS has an “empty” area between the north end of the platforms and the actual entrance to the tunnel, which is typically used for equipment storage these days, but which would have room for an extended center track. There is no similar “empty” area in PSS or USS. If you’re basing your conclusion strictly on the length of the platform itself, I think you may be shortchanging the length available for a center track at IDS.

    Does anyone have links to detailed diagrams of PSS or USS?

    1. I haven’t been able to find actual measurements, but PSS, USS, and WS have extended areas in the middle south of the platform areas.

      Take a closer look at the diagram, and it appears that the plan is to demolish some of the space between the tubes under Jackson St. If demolition of space between tubes is required, doing so under Jackson St seems like a more difficult proposition than north of the other three stations.

      1. Thanks.

        My impression based on that plan is that there is no need to clear additional station space (which would indeed be very expensive and difficult), because the existing tubes don’t start until north of Jackson. That seems right to me based on my own time in the tunnel. There is a lot of room north of the platform in IDS before the tubes start, enough to have a couple of buses waiting in line southbound. I don’t think the extra space in either PSS or USS is nearly so generous, although the longer platforms in USS would help to some extent.

        If there is room to turn around a four-car train in PSS or USS, then I’m 100% for moving the turnback there. I’m not in favor of building any turnback that’s limited to a three-car train.

  4. East Link will cause a redesign of the NB central link approach track to IDS which would make it impossible to put the turn back track in the current IDS bus layover space.

    As for an alternative location for a turn back track (other than IDS) how about using Convention Place Station for that? Since it won’t be a station anymore (most likely it’ll be used as a hidden bus layover spot) maybe there’d be room for a turn back track as well

    1. Using Convention Place, or the approach to it, would require having a track cross over the southbound track from Capitol Hill Station, which would be a highly unusual, and possibly unacceptably dangerous, situation for railroad tracks. If not, it might be possible to just use the space leading to Convention Place, and still allow the old station area to be redeveloped. I’m also not sure whether the stub tunnel could be modified to make room for a turn-back track between the tracks to CHS.

      1. “Using Convention Place, or the approach to it, would require having a track cross over the southbound track from Capitol Hill Station, which would be a highly unusual, and possibly unacceptably dangerous, situation for railroad tracks”

        That’s not uncommon or dangerous.

      2. Some of the “safety” arguments being pushed are bizarre in the extreme. They might make sense if we were planning on running without a modern signaling system, and I use the term modern loosely: most of these issues were adequately addressed over 100 years ago.

      3. I disagree. With modern signaling this would be perfectly safe … and we already know that there is space for a 4 car train as the station was designed for rail (albeit incorrectly).

        CPS would make an ideal location for the turnaround track as well as storage for extra trains for events, etc …

    2. This is the best idea yet: it addresses the fact that inbound East Link riders will most likely be headed for downtown stations. If the trains go out of service south of downtown rather than north, it will force almost all riders to transfer unnecessarily. If the trains go out of service at Westlake before turning around at CPS, these riders’ needs will be better served.

      1. The logical place to terminate the E-Link trains is in Ballard. Think about the options:
        1. Bellevue to UDist and beyond is better via current bus routes across SR520. Link is no improvement for all those riders, the vast majority of time.
        2. If Elink went to Ballard, via CPS junction (all grade seperated), then all those stops (SLU, LQA, Interbay, Ballard) are a continuation of the E to W trip. (If you look at O/D pairs, it’s far more functional than going to Lynnwood)
        3. The only drawback is for Elink riders going to CapHill, which is only a handful of riders, and they could easily transfer at Westlake or Udist stations.
        Why ST and STB completely ignore the obvious is beyond me.

      2. That decision was made years ago, and was solidified when ST2 passed saying that East Link would go to Northgate/Lynnwood. ST has been counting on East Link to supplement the frequency on the north line, and you can be sure that north side residents who had been expecting East Link (and voted for ST2) would have loud opposition to it. You can lament the past but it does no good to keep getting outraged over it again and again. It’s more productive to put energy into influencing decisions that haven’t been made yet.

    3. Would we even need to build anything at Convention Place to facilitate a turnback? If the trains are going to block the southbound track anyway they might as well just use the existing crossover switches to slot right onto the SB mainline.

      Of course then the operator would have to hop out and run to the other end of the train, which I guess would probably take far too long. Maybe a turnback/pocket track at Westlake makes the most sense.

      1. Of course then the operator would have to hop out and run to the other end of the train, which I guess would probably take far too long.

        Yeah, that’s the issue. You don’t want to be blocking an in-service line while you wait for the operator to move to the other end.

        But, if it’s at Convention Place, then there’s no issue. You won’t be blocking ANY trains there.

  5. Here’s the letter I just sent to all the ST Board members (

    Good day, Boardmembers:

    I’m writing as a constituent who is concerned about the decision to construct a turnback track in the center of International DIstrict/Chinatown Station (IDS), as approved by the Board in motions M2013-48 and M2013-49.

    This would be a terrible waste of a fantastic opportunity to provide a seamless transfer between northbound East Link trains and southbound Central Link trains, as well as a sacrifice of station capacity that would be extremely handy on CenturyLink Field game days.

    Our underground stations, and in particular the Transit Tunnel stations with their large mezzanines and end-of-platform staircases, are constructed in such a way as to introduce a significant penalty for transferring between platforms. This normally isn’t an issue unless one has missed their stop, but the East Link/Central Link transfer presents a unique case within our system. An across-the-platform transfer would be a significant improvement to the passenger experience, particularly for those who are carrying luggage to SeaTac. Its absence might not be _the_ deciding factor in one’s choice not to take the train to the airport, but it could add sufficient unnecessary friction to the experience that some passengers opt to continue taking private transport from the Eastside to SeaTac.

    Furthermore, IDS is clearly the station of choice for riders attending Seahawks and Sounders games. A center platform would make it possible to segregate Eastside passengers from South Seattle passengers. Under normal circumstances, the center platform would not be accessible from the mezzanine, but only for cross-platform transfers; during game events the platform could be opened for Eastside-bound passengers, and East Link-bound trains would only open their left-side doors.

    Please consider amending your contracts to construct the turnback track farther north along the line. We need to do all we can to save Link from death by a thousand cuts.

    Kyle S.

    1. I appreciate you contacting the board!

      A couple thoughts on the post-game segregation idea:

      1) Previous off-the-cuff remarks from an ST spokesperson cited the dangers of having too many fans on the center platform after events. But if some of the eastbound passengers are getting on at Stadium Station, and then transfering to East Link across the IDS center platform, while others who walk to IDS are getting on East Link via the west platform, that would actually reduce dwell time over only using the 16 doors facing the center platform.

      2) Getting eastbound passengers to use the normally emergency-only elevators to access the center platform would take a lot of educational effort, both to get post-event eastbound passengers to take that path, and then to get them to not take that path when boarding at other times. I think the approach of not opening the doors to the outer platform would be excessively confusing and troublesome.

      3) Perhaps, if the elevators were always in use, more people could be encouraged to enter the trains from the center platform, to even out the passenger boardings and alightings on each side of the train. A downside is that ST might then feel the need for elevators, stairs, and more ORCA readers to be added. Plus, it would mean passengers pushing past each other on the center platform to go in opposite directions, which gets back to the ST spokesperson’s fears of too many passengers on the center platform leading to someone being pushed onto the tracks.

      1. Great responses, Brent, and a good letter, Kyle–this is an important issue for all the reasons mentioned above.

        I am going to put on my d.p. hat for a moment to respond to the anonymous “ST spokesperson” who mentions the “fear of having too many fans on the central platform.” WTF? Seriously? Have these people EVER ridden public transport following an event anywhere in the world? Save the potential issue of people darting across the tracks if there is more perceived room on the other side (which can be mitigated by security and STEEP fines), why would there be any sort of capacity problem on one platform and not the other? The platform, whether it be one or two, will get as full as the number of people who desire to ride the train. Sometimes this might mean people waiting on the mezzanine, although that would take a great deal more ridership post-game than currently exists; having two platforms instead of one would add at least 50%–basically–platform standing capacity. (Note the space between the tracks in the photo of PSS above; it’s at least as wide as the side platforms.) If they are so afraid of actual passengers using the system to the point where they are afraid there might be too many, what have they done to mitigate that issue at Husky Stadium, where the capacity is larger than the cLink and a huge percentage of ticket holders have been used to taking public transit by way of the bus shuttles for years? There will be a LOT of game day use of that station!

        If only an elevator exists on each end without stairs or escalators, the people using that platform other than as a transfer is self-limiting because the elevator takes considerably longer for most people and so most people will take the stairs to the side platform rather than wait in line for the elevator to the center.

        I just don’t know what these people are thinking at times. This will be a crucial stop for transfers and making the bulk of people needing to transfer go up, across and back down again is ludicrous save for some overwhelming reason not refuted by Brent’s excellent post and some of the comments. “Death by a thousand cuts” is right.

      2. In order for a proper “Spanish Solution” to work at IDS (as I understand it, a proper “Spanish Solution” would mean all passengers would board and exit all trains to the west) you’d need full access between ground level and the center platform so that people exiting northbound trains could exit the station, and people boarding southbound trains could enter the station.

        So the center platform is the waiting platform for everyone going south or east, but the center platform is poorly suited to handle large crowds of people because there’s less room than the side platforms (less than in most center-platform subway stations, maybe as much as some of the older stations on the Chicago L that aren’t very well suited to large crowds) and both directions lead to the danger of the tracks (so that if the crowd draws back from an approaching train on one side it may push people into the tracks on the other).

        Pre-game crowds tend to arrive more dispersed than post-game crowds and they don’t wait at the station, so standard “Spanish” operation should work fine. Post-game crowds tend to arrive all at once, and wait at the station. It would be nice if people waiting for Central Link went to Stadium Station, but they probably won’t because they’re more likely to be able to board at IDS. So… post-game let people wait on either the center or west platform for trains going south/east (and the east platform for trains going north). Maybe assign someone to monitor crowds and direct people toward whichever platform has room. There’s no need to separate the eastside crowd from the south end crowd — keeping them mixed together gives you the flexibility to direct people away from the center platform if it’s too full for safety.

      3. (Also, if normal operation doesn’t work pregame because the huge number of people exiting trains coming from the north overwhelms center platform capacity, it’s easy as pie to let them exit onto the east platform as well. None of these adjustments are a big deal — in normal “Spanish” operation all the doors are open, and the only thing forcing people to exit west is convention and announcements, sort of like “exit to the rear” on buses today. A few confused people can be expected to go the wrong way without causing great harm, and on game days a crowd of people will do it and that will be fine.)

      4. Al, the flexibility you cite is precisely why I’d love to see the central platform built with full-service access (including mezzanine access), even if its use is only restricted to game days. But if all we can get is an emergency staircase, I’ll take it.

      5. For a variation on how the “Spanish Solution” might work in other stations, consider what Westlake Station would look like with a center platform, with elevators, escalators, and stairs to the suddenly useful mezzanine. The center platform could be set up as “exit only”. Westlake Station would no longer be the dwell-time bottleneck of the Link system. (Although, I’m afraid UW Station and U-District Station will become bottlenecks, and installing a center platform for a Spanish Solution might be a lot more difficult.)

  6. Speaking to the operations, the number of switches on the overall system remains the same, only the position of a couple components on dispatcher’s computer display screen changes.

    It’s also worth noting the space required to construct such a track. There needs to be some distance between the bumping post and train, distance between the bumping post and end of track, distance from the switch points to the train (for the signal equipment to work), a certain amount of space between the mainline switch and any sort of curve, and there’s the physical length of the switchwork. That alone can add 100-200 feet in addition to the space needed for 380’ of train. The key question here is “what is portal-to-portal distance in each of the other DSTT stations?” The big 4-car Link trains are already as long as the platforms.

    And, of course, there are added risks with running more trains farther north in the DSTT.

    One other turnback option could be sending a track or two up to Convention Place Station just before the crossover at the Pine Street Stub Tunnel.

    1. The Convention Place proposal would keep the number of switches at five, but add a riskier at-grade crossover.

      We haven’t discussed much what will become of the stub tunnel switches that currently exist. Might those still be usable after Capitol Hill Station opens? Is one of the tracks to CHS a continuation of the current turn-back track? If not, are those tracks being built around the turn-back track? Thanks for any and all additional information. (That goes for everybody.)

      1. A CP turnback would require a diamond crossing, not a crossover. I’m thinking something along these lines,-122.654641&spn=0.000339,0.000537&dg=optperm&t=h&z=21

        The switches will still be usable as the configuration is a scissor crossover with 400′ of tail track on the end. ULink simply connects to those 400′ track segments and continues on. There are several scissor crossovers already dispersed among the Link system (including one at UW Station) and they provide flexibility in the event single-track operations needs to occur.

    2. One thing to add to the operations discussion: Brent’s original post seems to have been written under the assumption that all the turnouts at IDS would be hand-thrown by an on-the-ground switchman:

      “The turn-back increases the number of switches station supervisors have to pay close attention to from two to five. On top of that, consider where the northbound split switch is proposed to be located: a mere several yards north of the northbound merge switch. Then, before the train turns back, two or three switches have to be flipped (depending on whether the train will then proceed east or south), all within close proximity. This should give some railroad safety experts at least a tinge of angst. … Moreover, the person in charge of the switches is responsible for the orientation of all five switches.”

      I design railroad and transit infrastructure for a living and ST’s proposed solution gives me no angst whatsoever. All of these turnouts will be controlled with electric motors remotely operated by the dispatcher, as Mike B. indicated, and with movement authority granted through trackside signal indications. Railroad signal systems are designed to be “vital,” which an electrical engineer friend of mine defines as: “where ‘vital’ means that failure can lead to loss of life (‘vita’ = ‘life’).” All turnouts would be interlocked as required, and the selection of a route would automatically line the turnouts correctly. Further, the vital signal system prevents inappropriate routings from occurring; for example, the DS could not line a southbound train away from the IDS platform if the turnback track switch was NOT lined for the straight route, or a southbound train moving from the turnback track could not be lined onto the northbound main track if that route has already been set up for a northbound train. Thus, the dispatcher would not be able to line a route which could lead to two trains colliding or a train crossing a turnout not lined for its direction of movement.

  7. Optimizing turnbacks is critical, and not putting in turnbacks both at IDS and above Westlake (as in Convention Place station site) would prove to be a very costly mistake that will plague operations with both tens of millions of lost dollars in productivity as well as service reliability problems as the system ages. This can plague Sound Transit for decades to come if it isn’t done right Just ask rail transit managers in many American cities about their operational disasters. No matter what the cost, do it right ASAP before it gets harder and much more expensive! Please lobby for a DSTT operations analysis and capital program as part of ST3. It’s the best thing that transit advocates can do right now for the region!

    1. I certainly hope such an analysis is done, if it hasn’t been done already, but 2016 will be a little late, when the ship has already sailed on some large construction contracts. We don’t even know for sure that an ST3 bond package will be put before voters in 2016. And, what if it fails? Do we then not do the safety analysis? I have a hunch a full analysis can be done within the current budget. I’m certainly with you, especially if the analysis looks at all possible ways to enable a center platform to be inserted at IDS.

      Having more, rather than fewer, turn-back tracks seems obviously better for operations when, not if, a train has to go out of service unexpectedly. But if that train has to stay where it is, on a particular track, until police clear it to move, we may wish we had more crossover tracks to get around every possible location for a train to break down or be ordered to stay put. The extra crossovers may also make maintenance easier, and affect possible span of service. If U-Link could run 24-hour service without getting in the way of the maintenance schedule at all, that would be just dreamy. Crossovers in the middle of each DSTT station that doesn’t have a turn-back track or center platform seem very feasible, and the 2019 conversion period might be the smoothest time to install them.

      Still the operational costs of not having the IDS center platform are much larger than the operational costs of making “disabled” trains continue up to CPS to get out of the way. Maybe I’m not getting what staff’s definition of “disabled” is.

  8. I agree that a central platform at the IDS station would be nice to have. It will certainly facilitate East-South transfers. That said, I find most of your other arguments somewhat dubious.

    Obviously, any additional complexity incurs additional chances for failure, so some of what you say about safety is probably at least partially true. Nevertheless, railways worldwide use turn back sidings like the one proposed daily without disaster. Interlocking systems eliminate essentially all of the human factors risk upon which you harp. In addition, any miniscule increase in the risk of a disaster needs to be weighed against the substantially easier emergency access at the IDS station as compared with the other much deeper tunnel stations. I strongly suspect that a thorough safety analysis would weigh in favor of an IDS turn facility for precisely these reasons.

    Operationally, a central turn back siding is far more convenient than would be a mere trailing crossover, since it allows reversals while fouling only one through route at a time.

    The suggestion that 3 minute headways are going to be impossible without a second platform is ludicrous. Far busier subway systems worldwide manage 2 and a half minute (or better) headways, often with rolling stock that is substantially less efficiently loaded than ours. They manage just fine without needing platforms on both sides. I’m not saying that two sided operations don’t improve dwell times, just that they only really become necessary when you’re trying for better headways far more ambitious than anything we seem likely ever to need.

    If stadium day crowding really became an issue, I suspect a better solution would simply be to non-stop South Link trains through the IDS station and force the use of the Stadium station. If the central platform ends up as narrow as I think it will, there’s a non-trivial chance it would have to be closed on such game days.

    So really, it comes down to the value of East to South connections versus the operational cost of placing turn back facility somewhere else. Unfortunately, without knowing how ST intends to use the facility this is difficult to gauge. If the second maintenance facility ends up on the Eastside, I suspect that it’s barely needed. If on the other hand, ST puts it on North Link, it’s going to see a lot of use, and it’s entirely believable that even one additional station will add substantial operating costs.

    1. “So really, it comes down to the value of East to South connections”
      High value.

      ” versus the operational cost of placing turn back facility somewhere else. ”
      Nil. Putting the turnback further north converts half-empty runs into *useful* runs, by making them stop at IDS. The added revenue more than covers any operational costs.

    2. The 3-minute minimum headway limitation is not fantasy. It is an actual limit Sound Transit has repeatedly stuck to every time someone has suggested capacity in the DSTT could go beyond that. If the 3-minute minimum headway assumes bottlenecks at IDS and Westlake, then lack of research and creative thinking among ST staff who had never contemplated the Spanish Solution and its variants may be robbing us of even more capacity.

  9. This is one of those areas where Link should just spend the money to do the job right. No center platform on the biggest transfer in the system? That is crazy. I really don’t care if they didn’t consider this sooner. That shouldn’t stop them from doing the right thing now.

    When they built the transit tunnel, they laid down rail, but it was the wrong gauge. They didn’t just throw up their hands and say “Oh well, it is too expensive to replace — I guess we better put the trains on the surface”. Of course not. They spent the extra money to do it right. In this case, it might not be that much money. But that misses the point. Even if it means we cut or delay other work, then so be it. For example, I would much rather have a center station then the station at 130th (in Bellevue). Most of the folks living or working on the Eastside would agree with me. Fortunately, there is enough money saved in other parts of the project so that we don’t have to make this kind of sacrifice. A center platform is not a nicety. It is a necessity. Without it, you are throwing away much of the benefit of having the trains run on the same track.

    I sometimes wonder if Link leadership really understands commute patterns in this city and who can benefit from Link. It’s not about going downtown. People can get downtown really well on the bus. They have for the last forty years. That is why the Tukwila station is primarily used by folks who work in Tukwila, not folks who ride the train from the suburb to downtown.

    Even getting to downtown Bellevue isn’t too bad. The bad part is transferring. Ask anyone who complains about their transit commute and they will inevitably mention the transfer. With East Link complete, a lot of people will do three transfers a day (bus to train, train to train, train to bus). For Link to work properly, we have to make sure the transfers are really fast.

    1. When they built the transit tunnel, they laid down rail, but it was the wrong gauge.

      It wasn’t the wrong gauge, they were the correct rails and the trains could have run on them just fine. The issue was that the rails weren’t well electrically insulated and couldn’t be safely used for our electric trains without endangering various nearby utility conduits.

      The rails were supposed to be installed fully insulated, but budget cutbacks in ’88 removed the insulation to save 1.5 million.

  10. In the case of this, a center platform should be built at Westlake AND IDS and East Link trains terminating between Westlake and the Pine Street Stub tunnel. It makes perfect sense and gives the operation much more flexibility. This also allows CPS to be reused for whatever development. If I recall, there is room for a 4-car trainset between the stations.

    Several LR lines feature such a maneuver, Portland (They have 3 unique areas that does this), Denver, Salt Lake, etc.

    While I can understand why the decision to do IDS but it is NOT the right decision to make.

    1. Thanks for the list of some other places that do turn-backs involving at-grade crossovers. Might you have links to the diagrams of these turn-backs, so we know we’re talking about the same configuration?

  11. Is there ANY way to get those trains going faster? The slowness of those trains is really costing them. That’s why they need so many trains going in and out of service. If they can get the trains going at 70 miles per hour on the straight sections of track, then that will save them a whole lot of hassle later. Oh, and the riders also get a faster ride :-)

    Maybe they could have some sort of magnetic solution to keep them on track? It just seems like there should be a way to make it work.

    1. The trains are rated for 55 mph.

      The capital costs for surface segments should include a component for the externalized costs of slowing down passengers, making the line less competitive with driving, and the delays and life loss due to collisions, but they don’t.

      1. Those costs should certainly enter into the cost/benefit calculation, but they should not be included in capital costs because they aren’t actually paid out in real money.

      2. Wouldn’t the capital be worth it if it means not having to take around 250 trains in and out of service each week day? Then, it would look less and less like “light” rail, but it is already the heaviest “light” rail I have seen.

      3. Each design decision that requires an additional train due to lengthening the total trip time should clearly be counted as a $16 million capital cost. That goes as well for every station that might be a dwell-time bottleneck and doesn’t take advantage of all 32 doors.

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