The 19th Avenue Subway

The Market Street Subway is a bottleneck for the Muni Metro system, since each of its lines eventually merges into it. Early documents show plans for a four-track subway under Market; alas, we didn’t commit to that project and now we are stuck with a two-track subway. Combine this with the fact that the surface segments of each line force Muni to run one- and two-car trains where the stations could handle a lot more and it’s easy to see that we’re leaving tons of capacity on the table.

The Central Subway pulls half a line out of the Market Street Subway, which probably won’t improve the situation since we still have five lines in the subway at all times. In addition, the new Parkmerced developments are going to add thousands of daily riders to the M Ocean View line, which runs in mixed traffic on 19th Ave and is prone to some of the worst gaps and delays in the whole system. Muni decided to look at improving this line next. They did some studies, offered some suggestions that seemed lacking in the long term, and collected a bunch of community feedback.

Last month, something interesting happened: Muni greatly increased the scope of the project. The details can be found here, and I encourage you to go read those before I poison your thoughts with my editorializing.

If completed, Muni will have built its first fully grade-separated metro line, and it would improve the situation throughout the system. The M would be free of just about all gaps and delays, and it would use 4-car trains, greatly expanding the capacity of the Market Street Subway. West Portal will be able to handle many more trains and people. St. Francis Circle will be free of the crazy signaling, the intersection will be less complicated, and pedestrians will be able to make more use of the metro there. 19th Avenue will generally become more pedestrian-friendly and the line will better serve SFSU and Parkmerced. It’s a fantastic proposal, in my opinion. There are a few interesting details I’d like to point out as topics for further discussion or clarification.

J Ocean View

If this project completes as planned, the J will take over service in Ocean View. (We might need to rename some lines, but I digress.) The choice of the J to take over this part of the journey is interesting because it has a number of features limiting its capacity at the moment. One of the more frustrating issues with the J is the inability to run even 2-car trains along the line, because some of the stops would render the second car inaccessible. However, the plan explicitly talks about running 2-car J trains. Muni plans to remove one of the problem stops (Liberty St on the private right-of-way), but I’m not sure that this is the only one (21st St might be too short, and possibly Glen Park). This might boil down to adding a few square feet of concrete here and there, but it’s something that Muni hasn’t mentioned to date in its other Muni Forward plans.

This also means that the J will spend a much higher percentage of its time above ground and in mixed traffic, since it doesn’t look like there are plans to give it a red lane south of 16th St. This might not be an issue for Ocean View commuters trying to get downtown because I assume they will take the J outbound to SFSU Station and transfer over to the M, and it will probably be faster than what they have now. However, we have to be careful that we aren’t getting rid of delays on the M by simply passing them on to the J. The J will need extra reliability improvements so it can remain a useful part of the rapid network.

The Curious Case of St. Francis Circle

If you look at the rail map in the project details, you might notice the very strangely laid out subway station at St. Francis Circle.

st-francis-circle.png

At first, I took this to mean that the M trains coming through would always stop on the west side of the platform no matter which direction they are headed towards, and similarly for the K on the east side.

one-level-platform

This seemed like a strange interpretation because Muni is making this immense capital expenditure to get rid of delays and yet this seems like it might cause a lot of them. This limits the maximum frequency of trains through St. Francis Circle because they must maintain stopping distance while a train from the other direction is passing through. It also means that the M and K have the same maximum frequency in the station, which is not the most efficient way to do things—as extra capacity is needed, it would be more useful to swap out K trains for M trains and have some K trains terminate at St. Francis Circle. Riders could then transfer to the longer M trains for the rest of the journey. The K seems to have the same problem as the J in that it can’t support trains longer than 1 car, so running more frequent M trains through seems like a no-brainer.

I did some digging around in NYC Subway track maps to see if I could find an analog for this sort of station, and the closest thing I found was Queensboro Plaza:

queensboro-plaza

From the map alone it seems like Queensboro Plaza is structured the same way, with one track going through the station for the 7 and <7> and the other track for the N and Q. This doesn’t make sense when you’re running trains every two minutes in both directions. However, Queensboro Plaza is actually a two-level station, where the Manhattan-bound trains from each line stop on one level and the outbound trains stop on the other level. Each train has two tracks going through the station. It’s possible SFMTA is planning a similar structure for St. Francis Circle station!

two-level-platform

The structure is a bit harder to see here, but the western side of the station would have M trains, and the eastern side would have K trains. This would allow them to run trains in both directions without a bottleneck, and would provide a way for the M and K to cross over each other without sharing a single switch. There are some drawbacks—building this station and track layout is probably way more expensive than the one-level layout, and the inbound and outbound tracks for each individual line don’t actually meet anywhere, meaning we couldn’t terminate K trains at this station like we wanted to. In the one-level world, we can pull a train into the station and just back it out when it’s ready to turn around. With the two-level design, we’d probably have to run them to West Portal and turn them around there, which defeats the point. (This might still help since we can pull the K trains back before the L trains merge into the subway towards Forest Hill, but M trains might be stuck waiting for K trains to turn around at West Portal anyway.)

I guess the moral of the story here is that I’m not really sure what they want to do with this station, but the track layout they’ve picked makes me a little worried that we will again run into capacity issues sooner than we’d like.

The Daly City Extension

The plan leaves room for the extension of the subway to Daly City BART. BART and Muni already have plenty of connections at Balboa Park, but this one would be pretty useful because data from the Transit Effectiveness Project/Muni Forward on how people use the 28 and 28R (formerly 28L) show that Daly City BART is a good anchor for the line. Linking SFSU with Daly City by a direct subway connection is probably a really good idea since those are the busiest stops along the corridor.

This would also offer a kind of redundancy with BART in that there would be two discrete grade-separated lines from Daly City to Embarcadero, which would improve the resilience of the whole system in San Francisco. If BART is having problems in the city, the M might be a good substitute for people commuting up from the south. Of course, this might cast the lack of integrated fares into sharp relief, but that’s a much more complicated issue for another post.

Similarities to New Muni Metro

Back at the end of 2014, Nextransit published the first part of their New Muni Metro plan. The principles behind the Ocean View plan and the New Muni Metro plan are similar, though New Muni Metro didn’t expect to launch into multi-billion dollar capital projects for a long time. But they realized that we already have a fully-grade separated line if we end the Market Street Subway lines at West Portal. All of the other lines are streetcars only and people transfer to the Market Street Subway at West Portal (K, L, M), Church (N, J), or Embarcadero (T). The New Muni Metro plan also involves some line fusion, with the J taking over the surface portion of the K, and the L taking over the surface portion of the M. This means we could run all of the surface lines more often without worrying about whether we’re overloading the subway, and the subway will be able to run longer trains all of the time because there won’t be any short stations along its path. Higher surface line frequencies plus long, extremely frequent subway trains will mean way more capacity and generally shorter trips, even if you have to transfer.

I think the most interesting part about the similarity is that it means Muni could probably experiment with this same kind of service, should capacity become an issue. I alluded to this in terms of substituting K trains for M trains in the St. Francis Circle station design, but we could theoretically do this with any type of train. Forcing people to transfer probably wouldn’t make everyone happy, but the trains would be less crowded this way, so it might work out!

However the details fall out, this is incredibly exciting news. Transit agencies often avoid making grand plans like this because the funding for grand plans has dried up, but if we know that we’ll be getting something this useful out of it, the political situation might be workable after all. We shouldn’t be afraid to dream big—even if these projects seem expensive, they’re necessary, and nobody will look back on it in the future and think it was money poorly spent. Let’s see how Muni builds on this in the coming years!

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