Intercity Trains and Long Island
Amtrak wants to extend three daily Northeast Corridor trains to Long Island. It’s a bad idea – for one, if the timetable can accommodate three daily trains, it can accommodate an hourly train – but beyond the frequency point, this is for fairly deep reasons, and it took me years of studying timetabling on the corridor to understand why. In short, the timetabling introduces too many points of failure, and meanwhile, the alternative of sending all trains that arrive in New York from Philadelphia and Washington onward to New Haven is appealing. To be clear, there are benefits to the Long Island routing, they’re just smaller than the operational costs; there’s a reason this post is notably not tagged “incompetence.”
How to connect the Northeast Corridor with Long Island

The Northeast Corridor has asymmetric demand on its two halves. North of New York, it connects the city with Boston. But south of New York, it connects to both Philadelphia and Washington. As a result, the line can always expect to have more traffic south of New York than north of it; today, this difference is magnified by the lower average speed of the northern half, due to the slowness of the line in Connecticut. Today, many trains terminate in New York and don’t run farther north; in the last 20 years, Amtrak has also gone back and forth on whether some trains should divert north at New Haven and run to Springfield or whether such service should only be provided with shuttle trains with a timed connection. Extending service to Long Island is one way to resolve the asymmetry of demand.
Such an extension would stop at the major stattions on the LIRR Main Line. The most important is Jamaica, with a connection to JFK; then, in the suburbs, it would be interesting to stop at least at Mineola and Hicksville and probably also go as far as Ronkonkoma, the end of the line depicted on the map. Amtrak’s proposed service makes exactly these stops plus one, Deer Park between Hicksville and Ronkonkoma.
The entire Main Line is electrified, but with third rail, not catenary. The trains for it therefore would need to be dual-voltage. This requires a dedicated fleet, but it’s not too hard to procure – it’s easier to go from AC to DC than in the opposite direction, and Amtrak and the LIRR already have dual-mode diesel locomotives with third rail shoes, so they could ask for shoes on catenary electric locomotives (or on EMUs).
The main benefit of doing this, as opposed to short-turning surplus Northeast Corridor trains in New York, is that it provides direct service to Long Island. In theory, this provides access to the 2.9 million people living on Long Island. In practice, the shed is somewhat smaller, because people living near LIRR branches that are not the Main Line would be connecting by train anyway and then the difference between connecting at Jamaica and connecting at Penn Station is not material; that said, Ronkonkoma has a large parking lot accessible from all of Suffolk County, and between it and significant parts of Nassau County near the Main Line, this is still 2 million people. There aren’t many destinations on Long Island, which has atypically little job sprawl for an American suburb, but 2 million originating passengers plus people boarding at Jamaica plus people going to Jamaica for JFK is a significant benefit. (How significant I can’t tell you – the tools I have for ridership estimation aren’t granular enough to detect the LIRR-Amtrak transfer penalty at Penn Station.)
My early Northeast Corridor ideas did include such service, for the above reasons. However, there are two serious drawbacks, detailed below.
Timetabling considerations
Under current plans, there is little interaction between the LIRR and the Northeast Corridor. There are two separate routes into Penn Station from the east, one via 32nd Street (“southern tunnels”) and one via 33rd (“northern tunnels”), each a two-track line with one track in each direction. The North River Tunnels, connecting Penn Station with New Jersey and the rest of the United States, face the southern tunnels; the Gateway tunnels under construction to double trans-Hudson capacity are not planned to pair with the northern tunnels, but rather to connect to stub-end tracks facing 31st Street. For this reason, Amtrak always or almost always enters Penn Station from the east using the southern tunnels; the northern tunnels do have some station tracks that connect to them and still allow through-service to the west, but the moves through the station interlocking are more complex and more constrained.
As seen on the map, east of Penn Station, the Northeast Corridor is to the north of the LIRR. Thus, Amtrak has to transition from being south of the LIRR to being north of it. This used to be done at-grade, with conflict with same-direction trains (but not opposite-direction ones); it has since been grade-separated, at excessive cost. With much LIRR service diverted to Grand Central via the East Side Access tunnel, current traffic can be divided so that LIRR Main Line service exclusively uses the northern tunnels and Northeast Corridor (Amtrak or commuter rail under the soon to open Penn Station Access project) service exclusively uses the southern tunnels; the one LIRR branch not going through Jamaica, the Port Washington Branch, can use the southern tunnels as if it is a Penn Station Access branch. This is not too far from how current service is organized anyway, with the LIRR preferring the northern (high-numbered) tracks at Penn Station, Amtrak the middle ones, and New Jersey Transit the southern ones with the stub end:

The status quo, including any modification thereto that keeps the LIRR (except the Port Washington Branch) separate from the Northeast Corridor, means that all timetabling complexity on the LIRR is localized to the LIRR. LIRR timetabling has to deal with all of the following issues today:
- There are many different branches, all of which want to go to Manhattan rather than to Brooklyn, and to a large extent they also want to go on the express tracks between Jamaica and Manhattan rather than the local tracks.
- There are two Manhattan terminals and no place to transfer between trains to different ones except Jamaica; an infill station at Sunnyside Yards, permitting trains from the LIRR going to Grand Central to exchange passengers with Penn Station Access trains, would be helpful, but does not currently exist.
- The outer Port Jefferson Branch is unelectrified and single-track and yet has fairly high ridership, so that isolating it with shuttle trains is infeasible except in the extreme short run pending electrification.
- All junctions east of Jamaica are flat.
- The Main Line has three tracks east of Floral Park, the third recently opened at very high cost, purely for peak-direction express trains, but cannot easily schedule express trains in both directions.
There are solutions to all of these problems, involving timetable simplification, reduction of express patterns with time saved through much reduced schedule padding, and targeted infrastructure interventions such as electrifying and double-tracking the entire Port Jefferson Branch.
However, Amtrak service throws multiple wrenches in this system. First, it requires a vigorous all-day express service between New York and Hicksville if not Ronkonkoma. Between Floral Park and Hicksville, there are three tracks. Right now the local demand is weak, but this is only because there is little local service, and instead the schedule encourages passengers to drive to Hicksville or Mineola and park there. Any stable timetable has to provide much stronger local service, and this means express trains have to awkwardly use the middle track as a single track. This isn’t impossible – it’s about 15 km of fast tracks with only one intermediate station, Mineola – but it’s constraining. Then the constraint propagates east of Hicksville, where there are only two tracks, and so those express trains have to share tracks with the locals and be timetabled not to conflict.
And second, all these additional conflict points would be transmitted to the entire Northeast Corridor. A delay in Deer Park would propagate to Philadelphia and Washington. Even without delays, the timetabling of the trains in New Jersey would be affected by constraints on Long Island; then the New Jersey timetabling constraints would be transmitted east to Connecticut and Massachusetts. All of this is doable, but at the price of worse schedule padding. I suspect that this is why the proposed Amtrak trip time for New York-Ronkonkoma is 1:25, where off-peak LIRR trains do it in 1:18 making all eight local stops between Ronkonkoma and Hicksville, Mineola, Jamaica, and Woodside. With low padding, which can only be done with more separated out timetables, they could do it in 1:08, making four more net stops.
Trains to New Haven
The other reason I’ve come to believe Northeast Corridor trains shouldn’t go to Jamaica and Long Island is that more trains need to go to Stamford and New Haven. This is for a number of different reasons.
The impact of higher average speed
The higher the average speed of the train, the more significant Boston-Philadelphia and Boston-Washington ridership is. This, in turn, reduces the difference in ridership north and south of New York somewhat, to the point that closer to one train in three doesn’t need to go to Boston than one train in two.
Springfield
Hartford and Springfield can expect significant ridership to New York if there is better service. Right now the line is unelectrified and runs haphazard schedules, but it could be electrified and trains could run through; moreover, any improvement to the New York-Boston line automatically also means New York-Springfield trains get faster, producing more ridership.
New Haven-New York trips
If we break my gravity model of ridership not into larger combined statistical areas but into smaller metropolitan statistical areas, separating out New Haven and Stamford from New York, then we see significant trips between Connecticut and New York. The model, which is purely intercity, at this point projects only 15% less traffic density in the Stamford-New York section than in the New York-Trenton section, counting the impact of Springfield and higher average speed as well.
Commutes from north of New York
There is some reason to believe that there will be much more ridership into New York from the nearby points – New Haven, Stamford, Newark, Trenton (if it has a stop), and Philadelphia – than the model predicts. The model doesn’t take commute trips into account; thus, it projects about 7.78 million annual trips between New York and either Stamford or New Haven, where in fact the New Haven Line was getting 125,000 weekday passengers and 39 million annual passengers in the 2010s, mostly from Connecticut and not Westchester County suburbs. Commute trips, in turn, accrete fairly symmetrically around the main city, reducing the difference in ridership between New York-Philadelphia and New York-New Haven, even though Philadelphia is the much larger city.
Combining everything
With largely symmetric ridership around New York in the core, it’s best to schedule the Northeast Corridor with the same number of trains immediately north and immediately south of it. At New Haven, trains should branch. The gravity model projects a 3:1 ratio between the ridership to Boston and to Springfield. Thus, if there are eight trains per hour between New Haven and Washington, then six should go to Boston and two to Springfield; this is not even that aggressive of an assumption, it’s just hard to timetable without additional bypasses. If there are six trains per hour south of New Haven, which is more delicate to timetable but can be done with much less concrete, then two should still go to Springfield, and they’ll be less full but over this short a section it’s probably worth it, given how important frequency is (hourly vs. half-hourly) for trips that are on the order of an hour and a half to New York.

