Low- and Medium-Hanging Fruit

The entire process I try to apply to cost-effective rail construction is to figure out the best places to spend money per unit of time saved. Obviously, this is mainly for intercity traffic – for local traffic it’s more interesting to look at cost per rider – but it’s intercity traffic that benefits most from this kind of optimization anyway.

With the Northeast Corridor, there are definitively low-hanging fruit, such as new (non-FRA-compliant) rolling stock, raising superelevation, improving platform access within present infrastructure, and adding constant tension catenary south of New York. Those are so useful, in terms of cost per benefit to travelers, that they should all be pursued immediately. The more interesting question is what to do afterward. I’ve proposed a few things before, in various posts, but it’s more useful to talk about the general process of determining where to build, i.e. which fruit are medium-hanging and which are high-hanging. I think traditionally this boils down to two parameters:

1. Cost per minute saved, including by improving reliability. This is of course adjusted for demand: New York-Philadelphia minutes are the most important, then Philadelphia-Washington, then New York-Boston, and finally other corridors.

2. Reduction in operating cost. If the rest of the network is based on hourly trains, and you need to squeeze five additional minutes to reduce your travel time including turnaround to an integer number of hours, it’s worth spending the money on it to avoid needing extra trains, or a schedule that doesn’t match up with the rest of the network. (And the same is true if the network repeats every 52 minutes – there’s nothing magical about 60 here.)

However, three additional, less obvious parameters are important:

3. Usefulness to local transit, in terms of speed, reliability, etc. This essentially reduces the cost imputed to intercity trains per minute saved.

4. How low-hanging the fruit becomes if combined with another. The issue is that eliminating two adjacent slow zones in an otherwise fast run saves more than double the time of eliminating just one of the two; another way to think about it is that eliminating the second slow zone saves more time than eliminating the first. This can result in counterintuitive phasing in a constrained funding environment.

5. How high-hanging the fruit becomes if it is delayed. If there is significant disruption to service coming from construction, then it’s better to do it earlier than would be warranted based on pure cost-per-minute-saved calculation.

#3 features prominently in Amtrak’s preexisting planning – in fact, too prominently, with its emphasis on Gateway. It’s a matter of agency imperialism more than anything, but it can lead to good results elsewhere. It’s really points #4-5 that aren’t optimized – either the costs are out of whack, or they are ignored. Washington Union Station‘s remodeling is an example of overemphasizing #5 without considering the cost or the ability to use existing infrastructure more cheaply; Transbay Terminal‘s poor column placement is an example of ignoring #5 entirely.

The reason I push concrete-heavy improvements between New Rochelle and Stamford, but not between Stamford and New Haven, comes essentially from those three points. The Cos Cob Bridge replacement is good because of points #1, #3, and #5; an I-95 bypass of Port Chester and Greenwich then interacts with it positively because of point #4, and also provides a suitable passing segment between high-speed and express commuter trains. In contrast, the projects east of Stamford don’t interact so positively: they involve constructing various bypasses, at high cost per minute saved, in separate locations so that the same increasing returns do not exist, and generally it’d not difficult to connect the bypasses to existing tracks so that the disruption effect of #5 is not in place.


  1. lpetrich

    Would it be feasible to change NEC electrification to 60 Hz? It’s currently at 16 2/3 Hz. That would make it much easier to connect to the electrical grid – no need to keep aging inverters going.

    • Adirondacker12800

      It wasn’t feasible until recently. The equipment has to be able to run on two different frequencies during the conversion. Since most of the stuff running on the corridor was ….being used until fully amortized…. it wasn’t capable of running on two frequencies.

    • Richard Mlynarik

      Anything is possible, but in this case there’s little to nothing to be gained.
      The infrastructure exists. The conversion costs are high The costs (multi-system vehicles, maintenance of existing HV feeder systems and frequency converters) aren’t an order of magnitude out of line with the alternative.

      It’s like asking for BART to be standard gauged. Throw enough money at something and it can be changed. But is there really a significant problem that is being solved?

      In short, this is the antithesis of “Low- and Medium-Hanging Fruit”.

      • anonymouse

        There is something to be gained if capacity increases require additional electrical capacity, which means additional substations or frequency converters. In that case, the choice is between building more infrastructure for the existing 25 Hz system or converting a part of it to 60 Hz, since you’ll need to install new equipment anyway. But I think the biggest opportunity for that has already passed, as they’ve already installed the new Ivy City substation and a frequency converter at Sunnyside, which could’ve been the two logical places to start the conversion to 60 Hz. As it is, I’m also not sure that the electrical clearances in the North and East River tunnels are sufficient for 25 kV, so they’d still need to stick with the lower and less efficient voltage.

      • Adirondacker12800

        It very low hanging fruit if you are rebuilding from the ground up anyway. Some of this stuff has been around for 75 years. There’s bits and pieces around Philadelphia that have been around for almost a century.
        If you are rebuilding from the ground up anyway..
        There’s no conversion equipment to buy. Since it wasn’t installed it doesn’t have to be maintained. Modern equipment is very efficient but it’s not 100% efficient. Minor losses add up over the decades. The conversion equipment is less reliable than a plain old transformer. Wikipedia says peak demand is 225 megawatts during weekday afternoon rush hour. Cut that by 5 percent and that’s significant. The power factor will be slightly better. Not important if it was one trolley car but important if you are sucking up megawatts.
        Making the rolling stock capable of dual frequency operation makes it slightly more expensive. It makes it slightly heavier, not by much but there. It’s slightly more expensive to maintain. All of that adds up.
        … It’s why Metro North and NJTransit went with 60Hz during their rebuilds and not 25Hz. It’s why Amtrak has been talking about converting for decades.

        • Richard Mlynarik

          I wonder why Germany, Switzerland, Austria, Norway and Sweden — all of which care a great deal about operating cost, all of which have extensive experience with multi-system traction equipment, and all of which have carefully planned network-wide renewal programs — are all failing to undertake a progressive, slow, incremental but inevitable 25kv 50hz conversion program? Low hanging fruit: jump all over it!

          • Alon Levy

            Well, they do have orders of magnitude more track (and more traffic) under 15 kV 16.7 Hz than the US does under 12 kV 25 Hz.

          • Adirondacker12800

            Germany, Switzerland, Austria, Norway, Sweden, all maintain their systems and don’t have to replace the whole creaky antique mess all at once.

      • Joey

        Be careful. Some of us are just looking for an excuse to believe that changing BART’s gauge is as easy as replacing some electrical equipment.

        • Winston

          People get all bent out of shape about BART’s track gauge. It’s less significant than BART’s unusual loading gauge or its unusually lightweight equipment. There is no good reason to change what’s there and were someone seriously proposing a second transbay tube and a Geary subway, they should look very seriously at whether its better to be compatible with BART or the rest of the world. This isn’t the case for BART’s San Jose extension, which should have been, for many reasons, rest of world compatible. For that matter, BART between North Concord and Pittsburg as well as the Dublin line should have been built with standard gauge equipment, but that’s another story.

    • Alon Levy

      It would be interesting to cost it – it’s unclear to me whether it figures into Amtrak’s latest plans for constant tension catenary or not. The reason is not just to connect to the electrical grid, but also to avoid multi-voltage trains; Richard is right that those are no big deal, but the bigger transformers on board add several tons, and on the margins 12.5 kV restricts the maximum amount of power that can be drawn all so slightly. On top of that, there is otherwise perfectly good equipment for regional trains that’s 60 Hz only (the M8s), because with all the FRA weight increases it was too expensive to also add transformers for 25 Hz.

      • Adirondacker12800

        Metro North doesn’t need anything other than 60Hz. If they want to go to Penn Station they are going to have to buy new. They can lease ALP46s and multilevels, They can cook up a fleet that has LIRR third rail shoes. They could develop shoes that flip. They could wait until Amtrak converts to 60Hz. Since Amtrak has been proposing that the project to be completed in ten years for decades now it’s probably best to put off any decisions until there’s a firm date for East Side Access to open. Because until East Side Access opens there’s no capacity for Metro North. By the time this is in the foreseeable future the M10s will be on the drawing boards. If not the M12s.

        • Henry

          Shoes that flip already exist – before Eurostar was rerouted to St. Pancras, their trains used third rail shoes in the UK. Unfortunately, train drivers would often forget to flip the shoes and they would damage the trackside equipment in France. This happened so often that the French got angry and installed concrete blocks just outside the Chunnel to snap off the shoes before they did any harm.

          Seeing as how Amtrak doesn’t have the best reputation for competence, the whole “forgetting to flip shoes” thing might be an issue.

          • mulad

            Sheesh. Seems like something that should have been built into the signaling system, or at least triggered by GPS coordinates.

        • Adirondacker12800

          25kV, twenty five kilovolt. Everything in Connecticut is 60Hz – Hertz, the same as the stuff that comes out of North American outlets almost anywhere. Either 12.5kV or 25kV at 60Hz.
          Pelham – just north and east of where the New Haven Line branches off from the Harlem Line is where the trains change from third rail to overhead catenary. The overhead catenary was rebuilt in the 90s. At that time Metro North converted everything to 12.5 kV/60Hz. Same as the stuff that comes out of your outlet but at a much higher voltage. When Amtrak electrified New Haven to Boston they selected 25kV/60Hz. It’s almost trivial to run trains on one voltage and then on a different one. All you have to do is use switches – there’s more than one way to achieve that end but it can involve something as simple as switches. ( It probably won’t in a train built in 2010 but it can It would be a software controlled semi conductor implemented version of flipping a few switches ) So SLE could run M8s from Boston to Queens where the change from 60Hz to 25Hz occurs. But SLE runs from New London to Stamford and doesn’t really need to go to Queens. There are other solutions – running to Grand Central for one. if they want to go to Manhattan. Or using locomotive hauled trains like they do for the service to football games in at the Meadowlands in New Jersey if they want to take trains to Penn Station. It’s not something – using 25Hz and 60Hz – the current fleet needs to do.

          • DingDong

            Ahh thanks. If it wasn’t already obvious, I am not an engineer.

      • Jiim

        The 2010 Master Plan included a line item for additional frequency conversion capacity. So I guess Amtrak isn’t planning on converting to 60Hz anytime soon.

        As Adirondacker notes, this is something that has been kicked around for some time and I imagine the numbers have been run several times. Whether it’s worth while probably depends on the discount rate you apply.

        • Adirondacker12800

          You can’t run more trains or even longer trains if you are reaching the capacity of the converters. The circuit breakers will trip at the most inopportune times.
          If adding capacity costs X dollars, converting costs 10X dollars and their budget is 2X dollars they can’t opt to convert the system to 60Hz. Adding capacity lets them kick the decision down the road again while still adding trains. As an added bonus it increases the system’s stability…. they have blackouts and brownouts that probably wouldn’t happen if they were connected to the grid directly… or would be much shorter if they were connected to the grid directly. Added capacity will lessen the blackouts and brownouts.

          I can see four scenarios with different first phase of construction.

          Convert New York City first. It’s the most complex part and NJTransit crews are experienced with operating on two different phases in one trip. It’s a pity ARC was canceled. That was going to be at 25kv/60Hz and had the capacity to handle the current level of service if something went wrong on the 25Hz side. Probably enough capacity that they could regularly run weekend service out of the ARC terminal.

          Convert New Jersey first. It has the most trains and the experienced crews. Revenue service crews and maintenance of way crews since NJTransit operates on both 25Hz and 60Hz.

          Convert SEPTA first. It has the most 25 Hz mileage considering all of the stuff on their branch lines.. Experience could be gained on lines not on the NEC. One of those branch lines is the line to Harrisburg. I wonder how much time constant tension catenary would save on that line. And could, if need be, substitute diesel service when a line is in the middle of being converted.

          Convert MARC first. Least traffic and they could run diesel service if need be… but then by the time they get the money to do this MARC crews will have experience with running on two different frequencies because they will be running trains through the new tunnel to Baltimore.


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