In 2015, I argued that New York Penn Station should be replaced with a hole in the ground, and such a station would have sufficient capacity. I will defend those posts: in the 21st century, elaborate stations are not required for high-quality rail service, and it’s more important to have good passenger egress and intermodal connections than a signature station. The topic of this post is more niche: which rail lines should connect to Penn Station?
The three-line system
In all writing I’ve done on the subject since around 2010, I’ve assumed that Penn Station should be a three-line stations. In blog posts about regional rail for New York I’ve consistently called them Lines 1, 2, and 3; one map can be found in this post, with slightly less expansive version on Google Maps, and, consistently, Line 1 (red) is the existing Northeast Corridor, Line 2 (green) runs along the same route but uses the Gateway tunnel across the Hudson and then goes via Grand Central, and Line 3 (orange) connects the Empire Connection to the LIRR via a slightly realigned approach, otherwise using existing tracks.
At the station, their order from south to north is 2, 1, 3; the numbers are chronological (1 preexists, 2 is a higher priority to build than 3). Gateway is to enter Penn Station south of the existing tunnel and the room for a Grand Central connection is to the south (31st Street), forcing that line to be the southernmost. The East River Tunnels go under 32nd and 33rd, each as a track pair going in opposite directions rather than 32nd running eastbound and 33rd westbound, and the track pair under 33rd has a better connection to the LIRR while that under 32nd has a better connection across the Hudson; the Empire Connection loops under the Hudson tunnel to connect to southern tracks, but that’s a single-track link and needs to be doubled anyway, so it might as well be realigned.
With three lines and six approach tracks, Penn Station should have 12 platform tracks: each approach track should split into two and the two tracks should serve the same platform, a solution used for the expensive but operationally sound Stuttgart 21 project. There should not be any flexibility, save perhaps some emergency crossovers at the station, not to be used in service: the required throughput is so extensive that such flexibility is fake, reducing capacity by almost as much as the full closure of a track.
The footprint of the station looks around 155 meters wide gross, or around 145 net, corresponding to 24 per platform. The total width of the tracks is 1.7 (track center to platform) plus 4.5 (distance between track centers; Shinkansen regulations say 4.3) plus around 2 if a safety zone between each track pair is desired, which is a total of about 8 meters. The platform width is then 24 – 8 = 16. If a heavy column between two tracks adjacent to different platforms is required, this adds about another meter to maintain the safety zones, for a total of 9, resulting in 15-meter platforms.
15-meter platforms are extremely wide. Châtelet-Les Halles’s RER A and B platforms are 17 meters, and are wider than necessary; they in contrast have insufficient vertical circulation at rush hour. At 15 meters, there’s room for six escalators per access point and possibly also a staircase; at 16, there’s definitely room for the staircase. Six escalators can run without any rush hour variation, always three up and three down, and would still clear a full train with many standees in a minute. I do not foresee any capacity problems at the station if it is built this way.
But this leads to the question: since the platforms are so oversize, perhaps it is useful to have more of them at lower width?
The four-line system
Penn Station could potentially serve not three lines but four. Right now it only has infrastructure for a line and a half, and with Gateway it would have one and two halves; even three looks like a generational project. But there’s good cause to think even farther ahead and make room for a fourth line: a dedicated intercity railway. The four-line system would maintain Lines 1, 2, and 3 as above, but then add an unnumbered line with no regional trains, only intercity train.
This comes out of my ridership model for high-speed rail for the United States: at full buildout, the system would be difficult to fit into an approach track with regional trains, and regional trains would only be able to run every 5 minutes or even worse, rather than every 2 or 2.5. Moreover, once high-speed rail exists on the Northeast Corridor, the return on investment on extensions is so great that it is likely that such extensions will happen. Politics make such extensions even more favorable: high-profile investment in the Northeast’s intercity rail and in New York is likely to lead to demand for such investment in other regions, regardless of the business case, and it is fortunate that the business case for such extensions is strong independently of the politics.
I presume that, from south to north, the platform order should be Line 2 eastbound, Line 2 westbound, intercity eastbound, Line 1 eastbound, Line 1 westbound, intercity westbound, Line 3 eastbound, Line 3 westbound. The problem here is that Penn Station’s footprint is only adjacent to three east-west streets, not four, and so the intercity tunnels have to duck under private property, and the best place for them going east is to act as 31.5th and 32.5th Streets. Using the existing tunnels and then displacing regional rail to new tunnels is also possible, but less desirable: the existing tunnels have small diameter, and so it’s easier to keep them lower-speed while the new tunnels get to be bigger and support 200 km/h while maintaining enough free air to avoid creating pressure problems in passengers’ ears.
Under this system, the existing footprint of Penn Station is wide enough for 18 meters gross per each of the eight platforms, or 10 meters net. This is not out of the question, and would ordinarily be completely fine: it’s enough for four escalators per access point, or three and a staircase. At Penn Station I am slightly squeamish purely because on Lines 1 and 3 it’s the only city center station, and thus more crowded than the usual for a regional train station.
But it’s possible to slightly widen the footprint. Under no circumstances should there be any digging past the footprint of 31st and 33rd Streets: the cost of construction under existing buildings is too high. Plans for demolishing the block between 30th and 31st Streets (Block 780) are in an advanced stage, related to both a real estate deal with Vornado and plans for Penn Station South expansion, but they are extraordinarily expensive (around $10 billion at this point), and redevelopment of the block is easier on firma than over rail tracks. For all intents and purposes, the maximum usable footprint is between the lot lines of 31st and 33rd, which is 175 meters gross, perhaps 160 net with some distance between the dig and the lot line.
With 160 net meters, there are 20 meters per platform with tracks, or 12 per platform alone. This is wide enough for anything: four escalators and a staircase fit, which has enough capacity (albeit with some compromises) with permanent escalator directionality and more than enough if escalators run three-and-one at rush hour.
The benefits of creating about two extra meters per platform should be weighed against the cost of adding to the footprint of Penn Station, which is not $10 billion but also not zero, and I don’t want to make pronouncements without seeing a reliable estimate. This also depends on the difficulty of building intercity rail tunnels under private property.
A coordinated Penn Station rebuild plan should be considered together with some plan for how to use those tracks. Infrastructure investment must always come with a precise service plan, with sample timetables to the minute shared with the public for democratic review.
The upshot is that Penn Station rebuild must come with a good idea of how much service the region expects to run. A high-speed rail plan argues in favor of the four-line system, provided the cost of the extra tunnels is reasonable (low-to-mid single-digit billions; $10 billion is far too high). Otherwise, the three-line system is better.