When Should Cities Separate Short- and Long-Range Commuter Rail?

There’s a big difference between the various regional rail proposals I’ve made for New York and similar examples in Paris and Berlin: the New York maps go a lot further, and incorporate the entirety of regional rail, whereas the RER and the Berlin S-Bahn both focus on shorter-range, higher-frequency lines, with separate trains for longer-range service, generally without through-running. A number of New York-area rail advocates have asked me why do this, often suggesting shorter-range alternatives. Yonah Freemark made a draft proposal many years ago in which through-running trains went as far as New Brunswick, White Plains, and a few other suburbs at that range, on the model of the RER. But I believe my modification of the system used here and in Paris is correct for New York as well as the other American cities I’ve proposed regional rail in.

The reason boils down to a track shortage making it difficult to properly segregate S-Bahn/RER-type service from RegionalBahn/Transilien-type service. These are two different things in Paris, Berlin, Hamburg, and Munich, and Crossrail in London is likewise planned to run separately from longer-range trains, but in Zurich and on Thameslink in London these blend together. Separate operations require four-track mainlines without any two-track narrows at inconvenient places; otherwise, it’s better to blend. And in New York, there are no usable four-track mainlines. Philadelphia and Chicago have them, but not on any corridor where it’s worth running a separate RegionalBahn, which is fundamentally a short-range intercity train, and not a suburban train.

Scale maps

Here is a map of the Berlin S-Bahn (in black) and U-Bahn (in red) overlaid on the New York metropolitan area.

The reach of the S-Bahn here is about comparable to the size of New York City, not that of the metropolitan area. Even taking into account that Berlin is a smaller city, the scope is different. Service to suburbs that are not directly adjacent to Berlin the way Potsdam is is provided by hourly RegionalBahn trains, which do not form a neat network of a frequent north-south and a frequent east-west line through city center.

Here is the same map with the Paris Métro and RER; a branch of the RER D runs off the map but not much, and the RER E branches going east, still within the map box, go further but only every half hour off-peak.

The Parisian Transilien lines are not shown; they all terminate at the legacy stations, and a few have frequent trunks, generally within the scope of the box, but they don’t form axes like the east-west RER A and north-south RER B.

So what I’m proposing is definitely a difference, since I’ve advocated for through-running everything in New York, including trains going from Trenton to New Haven. Why?

Four-track lines and track segregation

In most of Berlin, the infrastructure exists to keep local and longer-range rail traffic separate. The Stadtbahn has four tracks, two for the S-Bahn and two for all other traffic. The North-South Tunnel has only two tracks, dedicated to S-Bahn service; the construction of Berlin Hauptbahnhof involved building new mainline-only tunnels with four tracks. Generally, when the S-Bahn takes over a longer line going out of Berlin, the line has four tracks, or else it is not needed for intercity service. The most glaring exception is the Berlin-Dresden line – the historic line is two-track and given over to the S-Bahn, requiring intercity trains to go around and waste 20 minutes, hence an ongoing project to four-track the line to allow intercity trains to go directly.

In Paris, there are always track paths available. Among the six main intercity terminals, the least amount of infrastructure is four-track approaches, at Gare de Lyon and Gare d’Austerlitz, with two tracks given over to the RER and two to everything else. Of note, the entirety of the Austerlitz network has been given to the RER, as has nearly all of the Lyon network, which is why the lines go so far to the south. The other terminals have more: Saint-Lazare and Nord each have 10 tracks, making segregation very easy. Only subsidiary regional-only stations have two-track approaches, and those are entirely given over to the RER, forming the eastern part of the RER A, the southern part of the RER B, and the western part of the RER C.

New York has a shortage of approach tracks. The reason for this is that historically the mainlines mostly terminated outside Manhattan, so the four-track approaches only went as far as Newark, Jersey City, etc. The LIRR has a four-track mainline into Penn Station from the east, which is why I’ve advocated for some segregation, but even that should eventually involve the express trains via East Side Access through-running to New Jersey; see the second map in this post.

On the New Jersey side there are plans for four tracks with new tunnels across the Hudson, but two tracks have to be shared with intercity trains, and there’s no easy way to neatly separate service into two S-Bahn tracks and two RegionalBahn tracks. In the short run, two of these tracks would have to include trains diverting west to the Morris and Essex Lines, which have a three-track main and therefore cannot segregate their own locals and expresses. In the long run, with the M&E system given its own tunnel across the Hudson, you could theoretically do two local and two express tracks, but that runs into a different issue, which is that east of Penn Station, there are two paths to New Rochelle, both of which have local stops.

The issue of having two paths between the city center station and an important suburban junction, both with local stations, is also a problem in London. North of the Thames, most mainlines are at least four-track, making segregation easy, hence the plans for Crossrail. The only exception is the Lea Valley lines. But in South London, lines are two-track – historically, railways that needed more capacity did not widen one line to four tracks but instead built a parallel two-track lines with its own local stations, often arranging the local stations in a loop. The result is a morass of merging and diverging lines reducing capacity, and London is only slowly disentangling it. In either case, it makes segregation difficult; Thameslink can’t just take over the slow lines the way Crossrail is, and therefore there are Thameslink trains going as far as Bedford and Brighton.

What does this mean?

It’s somewhat unusual for New York to get a regional rail network in which every train, even ones going to distinct cities like New Haven, is part of a central system of through-running. But it’s not unheard of – Thameslink works like this, so does the Zurich S-Bahn, and so does Israel’s national network with its Tel Aviv through-running – and it’s an artifact of a real limitation of the region’s mainline rail system.

But this should not be viewed as a negative. New York really does have suburban sprawl stretching tens of kilometers out. It should have suburban rail accompanying all these suburbs, and wherever possible, it should run on a schedule that is useful to people who are not just 1950s-style 9-to-5 commuters. Moreover, New York lacks either the vast terminals of Paris or the Ringbahn’s mushroom concept, which means trains from outer suburbs have nowhere to go but Manhattan, so they might as well be turned over into a through-running system.


  1. michaelrjames

    As the old maxim goes: a picture is worth a thousand words. Your two maps with overlays of either Berlin or Paris regional rail says it all. I suppose it is no accident but curious how each network actually fits NYCs suburbs etc including Staten island, Far Rockaway etc. I don’t know, but suspect, that the relevant powers, inasmuch as they prioritise rail transit don’t look to Berlin and Paris. Maybe to London which of course has its own problems from which they may take the wrong lesson: don’t even think about doing it. Like London, historically NYC gets special attention with periodic baling out by the feds but the US is a vast place with many big cities bursting with transport problems and there is a lot less national sentiment to spend federal dollars on a single city like NYC which has had privilege for the better part of two centuries or more.
    Of course London has run out of indulgence from the rest of the UK and the recent settlement to finish CrossRail was to put CR2 on the back burner.

    • Alon Levy

      To be fair, XR2 was a shitshow with way too much tunneling. They wanted a tunnel with stations paralleling the four-track SWML; even if you think two extra tracks on that corridor are needed, a) you can widen the SWML to six tracks without compulsory purchases, and b) if a tunnel is desired, put the express tracks in it so that it won’t have any stations, since it’s the stations that raise the costs so much. At the northern end, the plans for tunneling from KX to the Lea Valley lines were not as dumb but still pretty gratuitous; it boils down to development-oriented transit, i.e. for some reason they think they can’t add housing anywhere in North London except the Lea Valley lines, even in very low-density areas right next to Picc and Vic line stations.

      • Si Hollett

        They don’t think that “they can’t add housing anywhere in North London except the Lea Valley lines”. They just know its much easier to add housing where there’s not much already, where you don’t have to buy up several houses to build a mid-sized brownfield development (you just buy a warehouse), deal with NIMBYS, or rely on transport links that have capacity issues (this is why you cannot do much densification of very-low density areas right next to Picc and Vic line stations – demand is already pushing the limits of capacity as it is, and so creating more is asking for trouble), etc. Yes, OK, there’s issues with transport in the Lea Valley currently. But that’s why they proposed this sledgehammer to crack the nut, turning one of the least-served corridors in Outer London into possibly the most-served in order to unlock it’s potential for development. But that massive increase in capacity is not because Tottenham-Broxbourne (even massively redeveloped) needs such passenger capacity (though it does need the extra track capacity to get even a 4tph local service), but because the Victoria line is going to struggle with crowding in Islington unless something is done in the next 20 years – with or without big development adding an extra million people further up the line – and so adding Tottenham-Central London capacity is something worth doing.

        Crossrail 2 is sold as being driven by big developments (because development money/more people paying taxes is the only way its vast expense could be funded) but it’s actually ‘capacity gap’-orientated transport driven by transport concerns. Any and every capacity (tracks, trains, stations) problem on a rough SW-NE corridor tries to be fixed by the line – which just adds to the expense and undermines the effectiveness. It could certainly do with fresh eyes looking it when (if) they take it back off the shelf.

        So here’s two examples of such gaps, and how CR2 falls short in dealing with them:

        There’s 8 branches on the SW Metro (via Wimbledon) that have to squeeze into two tracks at Raynes Park. Building another set of tracks between Raynes Park and Zone 1, and then having two lines, neither of which have excess branching, is a very good thing. What does CR2 do? It proposes to take the 4 innermost branches (give or take) and put up to 30tph onto these branches having (mostly) segregated them from everything else. Excellent. This, however, fails as the project is trying to do a lot of other things and the new tracks serve a different part of Central London than the current ones and people complain that they their journey becomes much harder with the rerouting. And so the plans end up being that only 20tph making it to the SW Metro network from CR2, and there’s much more reverse branching than desired – only half of the branches will be dedicated to just one line.

        And these extra SWML tracks seem to be tunnelled for much longer than needed. That’s because they go off to try and sort out the Northern Line as something needs to be done, and CR2 is about the only scheme in town (because when one scheme costs so much, there’s not much room for anything else) that can do something. Twisting via Tooting might achieve some small relief, but bulging via Balham is very likely to not extract many people from the tube (via Stockwell or Kennington isn’t much longer and people entering the system there are mostly from the railway which goes to Victoria anyway) while also dumping more on it (as changing onto the Northern at Balham becomes an attractive route between Wimbledon and The City). CR2 is just wrong scheme for solving the problem, and this is the wrong problem for CR2 to try and solve – not least as it adds several billion to the price due to the extra tunnelling.

      • fjod

        As Si says, Crossrail 2 tries to do too many things at once, necessitating silly detours and loops. But you *do* have to tunnel in the south-west, both on the current looped route and on a do-nothing-to-help-the-Northern-line route through Wimbledon and Clapham Junction: https://pedestrianobservations.com/2020/11/13/surplus-extraction/#comment-90304

        And regarding tunnelling I think the northern end is worse! I have no idea why there is a proposed tunnel to New Southgate, which seems like a complete money sink. I also think the choice of route to Tottenham Hale and beyond results in a demand mismatch with the much more in-demand south-western legs.

  2. adirondacker12800

    including trains going from Trenton to New Haven. Why?
    I would like to know why. There already are trains that will take you from New Haven to Trenton. Without the use of ferry boats since 1917.

      • adirondacker12800

        The Vermonter schedule says it’s 129 miles between New Haven and Trenton. There isn’t going to be much demand even if the fare was free. The few dozen people a week who don’t want to make a reservation can change trains in Penn Station New York.

        • SB

          There might be some Princeton-Yale demand?
          The main purpose of through-running isn’t connecting two endpoints but increasing capacity in the core.

          • adirondacker12800

            New Haven is 72 miles from Grand Central and Trenton is 58 from Penn Station. That doesn’t sound very core-y to me. The demand for Princeton to Yale can use the same trains that serve the demand for Princeton to Harvard or MIT or Brown. The trains originating in New Haven can skip all the stops between Stamford and New Rochelle or the ones from Trenton skip all the ones between North Brunswick and Newark. And there be other trains servicing the other stations. It could be Stamford-Rahway. Or Stamford-Croton. Or ….

          • Henry

            But then that begs the question of why you would want to through run that far in the first place.
            At least from the north, there’s a whole lot of platform space at Grand Central at which to terminate trains, and even if you didn’t, you could just through run a Trenton train to somewhere far out but not quite to New Haven (stopping at, say, Fordham Plaza, New Rochelle, or Stamford)

          • Alon Levy

            The main reason to pair local with local and express with express is that if you’re on a local train out of New Rochelle, it’s likely you’re traveling locally, so the non-Manhattan destinations you’re likely to be interested in are local stops on both sides of Manhattan. And then once the train makes local stops to (say) Newark), you should run it as a local on the New Jersey side and not go as an express to Trenton.

            At longer range, if you’re in New Haven, then you’re traveling at longer range, so if you’re going somewhere you’re going to city center. Manhattan looms large, but if you’re not going to Manhattan then you’re likely going to a secondary center like Stamford, New Rochelle, Newark, New Brunswick, Princeton, or Trenton. The principle here is that the longer one travels, the more one’s destination is likely to be a CBD.

          • adirondacker12800

            Because the yokels have trouble with things more complex than blue trains and red trains? And local to Matawan, express to Jersey Avenue and express to Trenton makes their brains meltdown?
            It very unlikely trains will even be able to get from New Jersey to Fordham Road or anyplace else on the Harlem Line. The railroad they can already use is much farther east. It doesn’t have to be Trenton either. They could, if they wanted to, run trains from Summit to Stamford. Or from Montclair.

          • adirondacker12800

            There’s enough demand between New England and the Southeast for there to be Nozomi, Hikari and Kodama on the intercity system. And locals and expresses on the commuter trains. And subway with locals and expresses in New York and Philadelphia. “Fixing” Wilmington Delaware will be very very expensive. Don’t fix it. It gets twice an hour Kodama and the Hikari and Nozomi can be out on a bypass where the freight has been bypassing forever. There can be a train that makes all the stops in New England and then only stops in New York, Philadelphia and Baltimore before terminating in Washington D.C. And a Wilmington-Springfield Kodama that takes forever. It’s too bad it isn’t a blue line, red line and green line. You have a smartphone.

  3. Matthew A da Silva

    I know Barcelona partially mingles it’s inner suburban and regional lines. Several regional services use the Arago tunnel and one even uses the Meridiano tunnel, though none are truly through routed but terminate at Sants, L’Hospitalet, or Franca. Since the regional lines take up suburban capacity anyway, it seems like a lost opportunity to implement through-running and redevelop Franca into prime urban property.

    Click to access mapa_serveis_regionals.pdf

    • Mikel

      Yeah, Barcelona is interesting in that it is similar in size to Berlin but has a much messier system with very little 4-tracking — actually, 3 different systems with 3 different track gauges, which complicates everything.

      In the Pl. Catalunya / Av. Meridiana tunnel, the regionals coming from the north (R12) run local in the suburbs — they are just a few R4 services a day that run all the way to Lleida, so they don’t really waste capacity. On the south side there isn’t that much demand beyond Molins de Rei, where R1 trains terminate: the rest of the suburbs are already served at good frequency by FGC Llobregat, and the Penedès area (served by R4) is sparsely populated relative to the coastal corridor (served by R2).
      In the C. Aragó tunnel, the biggest capacity constraint is the flat junction that connects the branch to Estació de França with the R2 mainline. As you point out, I think it could make sense to join the R11 (regionals going north to Girona and beyond) with the R13/R14/R15/R16/R17 (south to Tarragona and beyond), terminating some of them at Granollers if necessary. I think the reason they don’t do that now, apart from frequency mismatch ans possibly issues with heterogeneous dwell times, is that those lines are not reliable enough due to all the interlining and complex stopping patterns, so by terminating them just after crossing the city prevents delayed trains from messing up the other half of the network. Ironically, killing the França branch and redeveloping the area would make it a much bigger destination than it is today…

      Oh, and there is a place where through-running would be very useful. The FGC Vallès network runs 34 TPH per direction (peak, before corona) on a 2-track tunnel with a 4-track terminal station and is at 100% capacity, so joining it with FGC Llobregat would be helpful. However that would be extremely expensive and disruptive so the 2021-2030 regional plan calls for a second Vallès tunnel (page 29) and for the two networks to meet with a transfer at Gràcia (page 25).

      • Matthew A da Silva

        Maybe I’m thinking in American costs, but this plan to build multiple new tunnels under la Serra de Collserola seems like it would be an insane cost. Likewise, building a line from Placa d’Espanya to Gracia, bypassing the Eixample seems like a considerable expense that would mainly just benefit wealthy Gracia residents without connecting people on the Llobregat network to new job centers

        • Mikel

          Sorry, I should have specified — the plan proposes three different alignments for further study; only one will be chosen in the end. And yes, you have to think in Spanish costs: a similar but different alignment (Pl. Catalunya to UAB) was estimated at 1.6 billion euros in 2016, which is reasonable given there’s a lot of potential for extra ridership and more capacity is urgently needed for expresses to Terrassa, Sabadell and the UAB campus (plus the faster trip times achieved by leaving only the locals on the current curvy line).
          The FGC Llobregat extension to Gràcia gives direct access to the left side of the Eixample, avoiding the forced transfer at Pl. Espanya to L1 (which is pretty crowded at that point) or to L3 with its weird route; it also connects with the future tram along Av. Diagonal. The long-term plan is to extend it to the Poblenou as a sort of inner-circumferential (L9 being the outer one), which would also allow through-running to UAB if they end up choosing the northernmost option for the new Collserola tunnel.

  4. Diego

    As pointed out on Twitter, in Brussels all trains (local, express, high speed) share the same tracks as they run through the Central station. The different service levels can’t really be separated since there are 6 tracks and giving over 4 tracks to IC trains would be too much and 2 tracks too little (the same applies to locals). I wrote about the infrastructure constraints in my blog, and how 100 tph (50 in each direction) might be achievable.

    • fjod

      Thameslink’s reliability is fine in 2020 (even pre-covid), and the inability to get 24tph is because of lack of stabling facilities near Maidstone (it reached 22tph in the peak before coronavirus cuts).

  5. Si Hollett

    The paragraph on London in the article (like so much about London on this site) looks like good analysis at a glance, but is an impression that gets the detail all wrong and looks odd if you look closer. I’ll limit myself to addressing the bit most relevant to the article’s topic of separating short- and long-range commuter rail: “Thameslink can’t just take over the slow lines the way Crossrail is, and therefore there are Thameslink trains going as far as Bedford and Brighton.”

    Thameslink *wanted* to go to Bedford and Brighton (both using the fast tracks of 4-track railways). It ended up running trains to St Albans (stopping service on the slows, segregated from all but freight, unlike the fast tracks service which shares with intercity), because nothing else would, and it sort of fell into providing the Sutton stopping service. 10-30 years after the tunnels reopened and the Thameslink programme (nee Thameslink 2000) has been all about improving and adding to the longer-range services (and trying, unsuccessfully, to ditch the shorter range services, save St Albans) by removing the capacity bottlenecks around London Bridge and allowing more trains to run that way.

    That Thameslink is a mix of distances is because they can’t shake off some of the stopping services, despite trying, rather than them being forced to have some longer-distance ones through track constraints.

    *Sure south of London is full of reverse branching and is a tangle of lines and that would have meant it wouldn’t have been neat and tidy (not that it is today), but Thameslink could have, especially in those early days, been a stopping-service focused system not sharing tracks with intercity trains other than some peak Bedford-Moorgate trains. It went a different direction instead. Furthermore, that issue with south London isn’t the “parallel two-track lines with its own local stations” instead of four-tracking issue as misdiagnosed in the article, but a different issue of having two core central destinations and a termini for each one. Only the Chatham Mainline has that longer-range sharing with shorter-range in South London (vs the West Anglia Mainline/Lea Valley lines, and the Chiltern Mainline in North London – ie 2 lines).

    • rational plan.

      The basic problem with South London rail lines is that most stations have services to separate Central London, terminals, Either the City (London Bridge, Cannon Street and Blackfriars) and the West End (Victoria or Charing Cross). Most People walk from these terminal stations to their jobs.

      To increase capacity the lines need to separated and most stations only serve one terminal. This requires a some new interchange stations and some selected track widening. It would allow many stations to have increased frequency and regular intervals.
      The problem is that many people would lose their one seat ride into town, and if you start out in the suburbs you can currently sit all the way in. This change would mean half the people at each station would now need to change somewhere in the inner suburbs (adding travelling time) and then probably having to stand the rest of the way. Everyone knows the metro-isation of the South and South East Commuter lines is relatively cheap way of increasing capacity. (included in the plan is upgrading to full digital railway and replacing the entire train fleet to the same train so the have higher capacity and more ideally have the same acceleration profiles. Politically though it is toxic, so it will inch it’s way slowly forward.

      • threestationsquare

        It’s particularly worth noting that (contrary to Alon’s frame) Thameslink services to Brighton run entirely on the fast lines, with service on the slow lines provided by trains from London Bridge, Victoria, and the East London Line.

        That said, while the lines relevant to Thameslink are all four track, inner and outer services sharing two-track lines does seem to be a potential issue for the North Kent Line, Mole Valley Line, and Waterloo-Reading Line in addition to the Chatham Main Line.

  6. Chris

    The Dresdener Bahn in Berlin was 4-tracked before WW2 and is just gaining the trains back now. Also various RB and RE around Berlin seem to run every 30 minutes, not just ever hour at least on weekdays.

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