To build high-speed rail on the Northeast Corridor cheaply, intercity trains will have to share tracks with regional trains at several locations, which between them comprise a majority of the corridor. At most of these, commuter traffic is heavy enough that it must be accommodated in some way; only in a minority is it so insignificant that Amtrak can feasibly kick trains out if need be. So far I’ve only explained how track-sharing can be done between Boston and Providence and between New York and New Rochelle, both far from the busiest segments of the corridor.
I’d like to start tackling the more difficult segments, New York-Trenton and New Rochelle-Stamford. Thankfully, they are almost fully four-tracked; the one exception is the North River Tunnels and the immediate approaches, where there is little speed difference between intercity and regional trains. Unfortunately, even four tracks are not enough to provide full separation between services that do not run at the same speed, because those corridors are busy enough to warrant both local and express commuter service. This requires some scheduling creativity. In both cases, what is required is having express commuter trains weave between the local tracks and the intercity tracks.
As before, my explicit assumptions are that the rolling stock is optimized, and that speed limits except those coming from right-of-way geometry have already been eliminated. However, since unlike the MBTA, Metro-North runs good rolling stock, and New Jersey Transit runs passable rolling stock, we can’t realistically expect either to buy the most powerful regional trains on the market; that said, New Jersey Transit is looking into new trains, and we will assume those trains will be in line with the high-performance but heavy Silverliner Vs. What we can expect is better on-time performance and less schedule padding. The amount of commuter traffic is assumed to be similar to or slightly higher than today; the outer ends of both lines can be expected to lose traffic from commuter to intercity trains, but the rest will not.
Complicating all this is the requirement of making all the trains cohere into one line. In other words, unlike the situation for Boston-Providence, Newark-Trenton can’t stand on its own; the trains need to depart Newark with suitable gaps to allow trains to come in from the Kearny Connection. Likewise, New Rochelle-New Haven needs to feed into New Rochelle-New York in such a way that trains can share tracks on that segment. The most difficult portion is then combining the two commuter halves of the Northeast Corridor together to allow through-running, without holding commuter trains for too long at Penn Station. One possibility is to expand the entire route between the tunnels and Newark to a long overtake segment, and have all commuter trains stop at Secaucus to further slow them down and permit intercity trains that arrived at New York second to arrive at Newark first.
Current peak traffic on New Jersey Transit’s Northeast Corridor and North Jersey Coast lines is 13 trains per hour. Of those, only 2 make local stops from Rahway north, and both are North Jersey Coast trains. An additional 2 trains are express North Jersey Coast trains, leaving us with 9 trains at Metropark (3 stopping from New Brunswick, 3 more stopping from Jersey Avenue, 3 super-express from Trenton).
The introduction of high-speed trains would change the distribution of demand dramatically. From Trenton, HSR would be far faster. Even from Princeton Junction, it would be substantially faster to take a commuter train south to Trenton and connect to HSR to New York. For passengers desiring a one-seat ride, trains could continue to run, but make more stops along the way. We may suppose that no commuter train will skip any stop from Metropark south, and that an additional 2 trains that currently run express to New Brunswick or Jersey Avenue will run local, providing the Rahway-Newark segment with a peak local traffic of 4 tph.
The desired ideal is that all commuter trains will stay away from the inner two tracks, with brief forays when absolutely necessary. The above rule regarding local runs ensures no overtakes among the commuter trains take place south of Rahway. We are then left with the task of ensuring all overtakes north of Rahway make use of the two existing six-track segments, around Newark Airport, and from just south of the Elizabeth curve to Union Interlocking between the mainline and the North Jersey Coast Line, the latter segment including Linden and Rahway.
Because the southern six-track segment persists through the interlocking, it provides a fully separated route between local coast trains and express mainline trains, and also between local mainline trains and express coast trains southbound. Slightly modifying the interlocking to allow a separated northbound path between local mainline and express coast trains that does not use the inner two tracks may be required.
Now, a Silverliner V running at 160 km/h appears to lose about 90 seconds to a high-platform stop. For the record, a FLIRT would lose 75 seconds. Since there are five local stops north of the interlocking, we have to deal with 7.5 minutes. With 2-minute headways, this means local trains can depart Newark 9.5 technical minutes ahead of express trains on the same branch (mainline or coast), and 6.5 ahead of express trains on the opposite branch. Since 11/9.5 = 1.16 and a 16% pad is excessive, 11 scheduled minutes of separation are enough, and we obtain the following option for departure times out of Newark:
Each local must serve a different branch from the express immediately following, since 9 < 9.5. The express afterward – for example the :17 express after the :06 local – is separated by 11 minutes, and so can run on any branch. This allows 16 tph, of which 4 are local, and at least 4 have to run on the New Jersey Coast Line. Of course not every slot has to have a train scheduled in it.
Adding local frequency at the expense of express frequency is possible, but requires tightening the gap between a local train and the express that follows it, unless we allow inconveniences such as serving the local stations at highly irregular intervals. For example, 10-minute local headways allow trains to depart Newark at,
The 8-minute difference means each express must serve a different destination from the preceding local, and this underserves the mainline at only 6 tph. We can add stops to the express trains (or saddle them with inferior, locomotive-hauled rolling stock), but two stops are required, unless New Jersey Transit makes sure to get cutting-edge trains, which is unlikely; with FLIRTs, the time difference shrinks from 7.5 minutes to 6.25 and only one stop is required. In either case, we might as well squeeze an :x8 express, also serving a different destination from the local ahead of it.
Another option is to use the Linden-Rahway segment for overtakes. Trains lose 3 minutes there. If we add an infill stop, they lose 4.5, which is very close to the 4 minutes required to switch the order of two trains. This means express trains need to approach Linden 2-2.5 minutes behind the locals, and thus leave Newark 7 minutes behind. We obtain,
Express :09 (different destination from the :00 local)
(12-minute clockface pattern)
Since 12-minute schedules are generally awkward and my New York-New Rochelle proposal uses 10- (below) or 15-minute schedules (in the original link), we should add a Newark Airport or Elizabeth stop to the express trains, and then they leave Newark about 5-5.5 minutes behind the locals, and we can have a 7.5-minute pattern, which divides 15 evenly. Alternatively, we can add the stop and then have a 10-minute pattern again. We either get 6 local and 12 express slots with each express serving a different destination from the local behind it, or 8 local and 8 express slots, and there is no restriction on destination:
Note that nowhere here does HSR share tracks with anything except maybe in the Newark Penn Station throat, under any of the options. Thus, any discussion of HSR speed zones is irrelevant, except perhaps at the final stage when some tweaks to the basic schedule are under consideration.
Like Newark-Trenton, this is a four-track segment. However, commuter traffic here is heavier, and there are no six-track segments. Instead, overtakes between express commuter trains and intercity trains must be done on bypass segments. The one that we will consider is, as I outlined before, a route from just south of Rye to between Greenwich and Cos Cob, following the I-95 right-of-way.
No HSR on the New Haven Line should be considered with New Rochelle as it is. The flat junction and S-curve together severely constrain train speed and capacity. Since the junction has to be grade-separated, and some takings are required, we might as well assume the separation allows trains to proceed without crossing opposing traffic no matter where they go. Furthermore, the station should be six-tracked if necessary.
We will also assume the curve has been partially eased, to a radius of 700 meters with appropriate superelevation spirals, permitting our example 375-mm-equivalent-cant trains 150 km/h. We will also assume that Harrison has been partially eased to 1,500 meters, permitting 220; that the curve toward the bypass around Rye is 1,500 meters, which may be slightly too optimistic but not by more than a few seconds of travel time; and that the curves farther north until the Stamford approach are 2,000, permitting 250. The approach to Stamford consists of two curves forming a wide S, the western one at 1,000 (180 km/h) and the eastern one at 800 (160). Note that these upgrades allow express commuter trains to travel at 160 on the shared segments – indeed, they require it to avoid or at least limit cant excess. Local trains have more limited cant because of the needs of freight.
We will assume the number of trains is about the same, with capacity boosted with longer trains; where New Jersey Transit runs 12-car trains because of limited capacity across the Hudson, Metro-North tends to run 8-car trains. Unlike in New Jersey’s case, there’s little point then in programming more slots for trains.
Let us now consider Easy Mode, with all Metro-North trains using the existing route to Grand Central. We have two track-sharing segments, one between New Rochelle and Rye, and one between Greenwich and Stamford. The first segment is 12 km long and has 3 stations with 2 more at the ends; the second is 8 km long and has 3 stations as well, with just 1 more at one end.
On the first segment, there are 18 Metro-North tph peak today: 12 not stopping at all, 2 stopping only at Harrison, and 4 local. Now if the express trains share tracks with HSR rather than the locals, we will want to schedule trains HSR-express-express repeating every 10 minutes, or HSR-express-express-express repeating every 15; the former allows more versatile HSR slots (local and express), and the 15-minute assumption of New York-New Rochelle has no relevance in Easy Mode.
Current scheduled time between Rye and New Rochelle is 17 minutes for local trains; judging by both rolling stock capability and the local-express schedule difference, nonstop trains take about 10 minutes, and trains stopping at Rye but not New Rochelle take 12. Sped up to 160 km/h, with 7% schedule padding, nonstop trains would take about 6 minutes. HSR would take 3:35, again padded 7%. This means that, with 2-minute headways in both directions (fast-ahead-of-slow, and slow-ahead-of-fast), and 6-minute express commuter trains, we can have (northbound times from New Rochelle, HSR passing and commuter trains passing or stopping):
This is because by Rye, the :10 HSR is still 3.5 minutes behind the :04 express Metro-North train.
Alternatively, it’s possible but very tight to have an express-express-local schedule, assuming commuter trains are not sped up but the stop penalty is reduced to 80 seconds (so, 4 minutes for 3 stops), which is feasible at the speeds of the line:
This requires express trains to weave effortlessly to tracks 2 and 5 of a 6-track New Rochelle station, or to stop at New Rochelle.
A mixed schedule, with half the express trains sharing track with HSR and half with the local trains, is also feasible, but is essentially like drinking half coffee and half tea: while the 8-minute local-express gap on the local tracks is fine as it is, the gap on the HSR tracks requires speeding up the express trains anyway.
Note that if the all express trains share tracks with HSR, it is trivial to add local service, or to replace express trains with locals.
The other segment is easier, because it is shorter and lower-traffic, with only 13 tph (3 local, the rest express). HSR would take 2:24 with pad; express commuter trains take 7 today and could take 3:24 with a speed-up. The speed-up would be very significant here as this is a slow segment today, with the movable Cos Cob Bridge restricting speeds. The present speed difference is already almost small enough to allow HSR-express-express, as above; we need to cut another 36 seconds from the express travel time, which we can do with improved reliability reducing padding (the pad I’ve observed between Stamford and Grand Central is 10 minutes). Local-express-express would be 7 vs. 12 minutes, and if locals could consistently take just 11 minutes, as some already do, or if expresses could easily weave to the express tracks just north of Greenwich after HSR trains diverge to the bypass, then it would be feasible.
To finish Easy Mode, let us reconcile the two segments, which after all are populated by the same trains. If we have HSR-express-express on both segments and use the bypass as an overtake, we need to ensure that a commuter train that was 2 minutes ahead of HSR before is now 4 minutes behind after: 4, and not 2, because each HSR train overtakes 2 express trains. Losing 6 minutes is difficult, as the current local travel time between Greenwich and Rye is just 7 minutes. But with approaches this is a bit more than 8 minutes, and HSR would do the segment in 2:08, padded. This has the only drawback of awkwardly making express trains make stops at Greenwich (understandable given traffic), Port Chester, and Rye.
As an alternative, we can also do local-express-express on one segment and HSR-express-express on the other. Since the HSR-express-express schedule is tighter on the southern segment, the southern segment should have local-express-express. This only requires us to avoid having trains run a mixture of local and express too much: as two of the Greenwich-Stamford locals run express south of Greenwich and three of the Harrison-New Rochelle locals only run as far north as Harrison, we can simply combine those to create more locals going all the way from Stamford to Grand Central.
Now, let us move on to Hard Mode, which includes New Rochelle-New York. A consistent 15-minute schedule does not look possible to me on New Rochelle-Stamford without reducing peak commuter traffic to 16 tph, for example by lengthening trains and platforms. If that were done, 8 tph local on the local tracks with 4 turning at or south of Greenwich, and 8 tph express in HSR-express-express pattern on the southern shared segment, would be feasible.
So let us consider 10-minute schedules. HSR and express trains run at almost the same speed, since there are few areas south of New Rochelle on which even 200 km/h is at all feasible. The difference between HSR and express 145 km/h M8s (stopping at New Rochelle and Sunnyside), as already investigated in my original post on the subject, is 3:15 without pad, and 3:29 with. This means the express needs to leave New Rochelle up to 4.5 minutes after the HSR train, so that it will arrive at Sunnyside 8 minutes after, and 2 ahead of the next HSR. With a 9-minute time difference between HSR and the express trains from Greenwich to New Rochelle, this requires the express to be at least 4.5 minutes ahead of HSR at Greenwich, which with very minor speed-up is possible. What this means is that with mixed HSR-express-express and local-express-express as in Easy Mode, the first express after each HSR will go to Penn Station and the second one will go to Grand Central.
The question then is what to do with local trains. If they only go as far north as Co-op City, then it’s easy; with the exception of Hell Gate Bridge, the tracks in the Bronx would have to be four-tracked anyway to allow some overtake, and since there’s room, there’s not much traffic now, and this represents an expansion of Metro-North service, we can safely assume four-tracking. In that case local trains, making no stops in Queens except Sunnyside, would run at the same speed as the express trains on the two-track segment south of Hunts Point, and could be scheduled anywhere. An Astoria stop would require them to be scheduled immediately after the HSR and express trains southbound, which is feasible as near Sunnyside those would be close together already, with the express just ahead of HSR.
Of course, as this is Hard Mode, we cannot assume the local trains turn at Co-op City. Instead, we will make them turn at New Rochelle, or ideally run through farther north as locals. Now, southbound HSR trains, we have established, pass New Rochelle at :00, express trains leave at :04:30 and :06:30, and local trains leave at :02:30. This means we should extend four-tracking at Co-op City such that the local goes at the exact same speed as the express, which does stop at New Rochelle, until after it diverges to the local tracks at Co-op City; alternatively, if there is room in the schedule, we can have the local trains leave at :02 and then there is enough room.
Rearrangement of trains heading toward Hell Gate should be considered a trivial problem: if locals are too far ahead, or too far behind, the number of stops could be adjusted, or they could be held at the Bronx stations longer. Because the time difference between a local and an HSR in the Bronx and Queens combined is just under 10 minutes, the first option would require an extra stop or two or longer dwell times, making the local lose a full 10-minute headway and thus come immediately after the next HSR. By then the express has shifted back to about :07-:08 and so it’s not a threat even if the local does make an Astoria stop.
None of this is elegant. The schedules don’t necessarily match. Local HSR trains would add extra complications, though at least they’d reduce the speed difference with commuter trains in Metro-North territory. All agencies involved need to be on the same page. Through-running would involve a multi-overtake schedule, in which the most local trains get overtaken several times, by different classes of trains (HSR and express). Punctuality doesn’t have to be Japanese, but it needs to be Swiss, or else the entire edifice collapses.
And it’s still far cheaper than trying to overbuild everything to prevent this mess. The only commuter trains sharing track with HSR in this region are Metro-North, and those are fairly punctual, though this involves heavy padding. The rolling stock assumed is already in operation or in the procurement stage. The track repairs required are straightforward, and the curve modifications required, while annoying, are not the end of the world; the one greenfield bypass follows an existing Interstate, and the takings required, while nonzero, are low.
The travel time implied for this is a little more than 17 minutes from Newark to Trenton, for an intercity train stopping only at Newark (though this requires a top speed of 360 km/h causing severe noise impact in New Brunswick and Trenton), a little more than 8 between New Rochelle and Stamford, and just less than 10 between Sunnyside and New Rochelle. Depending on how much speed can be squeezed out of narrow tunnels and a new Portal Bridge, about 11 minutes Sunnyside-Newark, including New York and Newark dwell times, could be done; this is about 46 minutes Stamford-Trenton, a segment that Amtrak currently does in 1:45 excluding the long New York dwell time. And the amount of concrete pouring required is quite small for an hour’s worth of travel time reduction. Even a top speed that’s less noisy and ambitious, and lower speeds through the existing tunnels, do not raise this travel time far above 50 minutes.