There’s an article in the New York Times by its architecture critic Michael Kimmelman, making a forceful case for the Gateway Project’s necessity. Like nearly all transit activists in New York, I think new Hudson tunnels are the top infrastructure priority for regional rail; like nearly all transit activists, I groan at Amtrak’s proposed budget, now up to $16 billion (but unlike most, I think that it should not be built unless costs can be brought down – I’d peg their worth at $5 billion normally, or somewhat more in a crunch). I would like to explain one specific piece of scope in Amtrak’s plan that can be eliminated, and that in fact provides very little transportation value: Penn Station South.
Like all proposals for new Hudson tunnels, Gateway is not just a simple two-track tunnel between New Jersey and Penn Station. No: the feuding users of Penn Station all think it needs more tracks. The rejected ARC proposal had a six-track multilevel cavern, and Gateway has Penn Station South, a proposal to demolish an entire block south of Penn Station and build seven additional platform tracks. The cost of just the real estate acquisition for Penn South: $769 million to $1.3 billion, at today’s prices. Trains using the preexisting tunnels would have to go to the preexisting Penn Station tracks, which I will call Penn Classic; trains using the new tunnels could go to either Penn Classic or Penn South, but the junction is planned to be flat. For illustration, see PDF-p. 12 of a press release of the late Senator Lautenberg, and a clearer unofficial picture on Railroad.net.
As a result of this proposed track arrangement, train services would initially suffer from the capacity limitations of flat junctions. Like Penn Station’s tracks 1-4, Penn South would be terminal tracks. This means that the only service possibilities are as follows:
1. Schedule all through-trains, such as Amtrak trains, through the preexisting tunnels.
2. Do not schedule any westbound trains from Penn South or any eastbound trains entering the preexisting Penn Station tracks: for example, no westbound trains from Penn South in the morning peak, and no eastbound trains entering Penn Classic in the afternoon peak.
3. Schedule around at-grade conflicts between opposing traffic.
Option #2 is impossible: Penn South has 7 tracks. If trains can enter but not leave in the morning, there will be room for 7 trains entering in the morning, a far cry from the several dozens expected. Option #1 is the better remaining option, but is ruled out, since Amtrak wants to use the new tunnels for its own trains. This leaves option #3, which restricts capacity, and complicates operations. Thanks to Amtrak’s imperialism, taking over regional rail projects for its own ends, Penn South has negative transportation value relative to just building new tunnels to Penn Classic’s tracks 1-4 (the transportation value relative to doing nothing is of course positive).
I emphasize that the negative transportation value of Penn South comes entirely from Amtrak’s involvement. The same infrastructure, used by passenger rail agencies that were more interested in providing high-quality public transportation than in turf wars, would have positive transportation value. However, as I explained to Kimmelman, this positive transportation value is low, and does not justify even the cost of real estate acquisition, let alone that of digging the station.
Briefly, as can be seen in the diagrams, the interlocking between the two new tunnel tracks and Penn’s eleven terminal tracks – tracks 1-4 of Penn Classic, and all of Penn South – is exceedingly complicated, which would limit approach speed, and not provide much flexibility relative to the number of tracks provided. This is to a large extent unavoidable when two approach tracks become eleven station tracks, but it does lead to diminishing returns from extra tracks. This is one of the reasons it’s easier if trains branch: it’s easier to turn 12 trains per hour on two tracks than to turn 24 on four (although both are done in Tokyo – indeed, the Chuo Line still turns 27 tph on two tracks).
Avoiding large crunches like this at urban terminals a benefit of through-running. This is hard to realize initially unless the new tunnel is what I call ARC-North. It’s still possible to through-run trains, pairing the new tunnels with the southern pair of East River Tunnels and the old tunnels with the northern pair, but it requires a lot of diverging moves at interlockings, limiting speed. Penn Station plans should be built with a long-term goal of simple moves at interlockings, to (slightly) increase speed and capacity and reduce maintenance needs.
However, it’s still possible to square the circle by requiring trains to turn fast on tracks 1-5 of Penn Station (track 5 splits to a terminating end and an end that runs through east of New York). Tokyo would be able to turn a full complement of 24 trains per hour on these tracks. Most other cities would not. However, as somewhat of a limiting European case, the RER A turns a peak train every 10 minutes on single track at Le Vésinet-Le Pecq, the next-to-last station on the Saint-Germain-en-Laye branch; Le Pecq has two through-tracks (also hosting a train every 10 minutes) and one terminal track. See map and schedule. This does not scale to 24 tph on four tracks; somewhat tellingly, those trains do not continue to the terminus, which is a three-track station, implying turning 12 tph on three tracks is problematic. The RER E turns 16 tph at the peak at Haussmann-Saint Lazare, a four-track city terminus, pending under-construction extension of the line to the west, which would make it a through-station.
If we accept 16 tph as the capacity of new Hudson tunnels without new Penn Station tracks, then the question should be what the most cost-effective way to raise future capacity is. An extra 9 tph, the equivalent of the difference between 16 tph and the 25 tph that the current tunnel runs and that Amtrak projects for Gateway, is within the capabilities of signaling improvements and better schedule discipline. Again looking to Paris for limiting cases, the combined RER B+D tunnel between Gare du Nord and Châtelet-Les Halles runs 32 tph, without any stations in the tunnel (the RER B and D use separate platforms), while the moving block signaling-equipped RER A runs 30 tph on its central segment, with stations (as do the S-Bahn systems of Berlin and Munich). The RER E was planned around a capacity of 18 tph, but only 16 tph are run today. 18+32 = 50 = 25+25. France is not Japan, with its famous punctuality: French trains are routinely late, and as far as I remember, the RER B has on-time performance of about 90% based on a 5-minute standard, worse than that of Metro-North in its better months.
More importantly, dropping Penn South from the Gateway plan saves so much money that it could all go to through-running, via a new tunnel from tracks 1-5 to Grand Central. This is about 2 km of tunnel, without any stations; in a normal city this would cost $500 million, the difficulty of building in Midtown canceling out with the lack of stations, and even at New York construction costs, keeping the tab to $2 billion should be doable. The 7 extension is $2.1 billion, but includes a station; an additional proposed infill station at 10th Avenue, dropped from the plan, would’ve $450 million, giving us $1.6 billion for about 1.6 revenue route-km, rising to 2.3 km including tail tracks – less than a billion dollars per kilometer.
At $2 billion, the premium over $1 billion of impossible-to-cut real estate acquisition costs is down to $1 billion. It’s unlikely the construction cost of Penn South could be just $1 billion, without general reductions in city construction costs, which would enable the Penn-Grand Central link to be cheaper as well. Each Second Avenue Subway station is about a billion dollars, and those stations, while somewhat deeper than Penn Station, are both much shorter and narrower than a full city block. The result is that building a Penn-Grand Central link is bound to be cheaper than building Penn South, while also providing equivalent capacity and service to a wider variety of destinations via through-running.
One difficulty is staging the tunnel-boring machines for such a connection: building a launch box involves large fixed costs, especially in such a crowded place as Midtown. One of the reasons Second Avenue Subway and the 7 extension are the world’s most expensive subway project per kilometer is that they’re so short, so those fixed costs are spread across less route length. The best way to mitigate this problem is to build the link simultaneously with the new Hudson tunnels. The staging would be done on Penn’s tracks 1-4, whose platforms would be temporarily stripped; the construction disruption involved in the tunnels is likely to require shutting those tracks down anyway. Depending on the geology, it may even be possible to use the same tunnel-boring machine from New Jersey all the way to Grand Central.
This doesn’t save as much money – the Penn-Grand Central link is extra scope, with its own costs and risks. However, unlike Penn South, it is useful to train riders. Penn South allows terminating trains at Penn Station more comfortably, without having to hit the limit of large-city terminal capacity; the Penn-Grand Central link creates this capacity, but also lets riders from New Jersey go to Grand Central and points north (such as Harlem, but also such more distant commercial centers as Stamford), and riders from Metro-North territory go to Penn Station and points west (such as Downtown Newark).
Normally, I advocate unbundling infrastructure projects, because of the tendency to lump too many things together into a single signature plan, which then turns into political football, a sure recipe for cost overruns. However, when projects logically lead to one another, then bundling is the correct choice. For example, building an entire subway line, with a single tunnel-boring machine and a single launchbox, usually costs less than building it in small stages, as is the case with Second Avenue Subway. New Hudson tunnels naturally lead into a new tunnel east of Penn Station, regardless of where this tunnel goes; and once a tunnel is built, its natural terminus is Grand Central.