Why is Princeton Trying to Downgrade the Dinky?

Regular users of the Northeast Corridor in New Jersey know that there is a short branch off the line serving Princeton. Mainline trains do not use it – they continue between New York and Trenton – but a two-car shuttle, affectionately called the Dinky, connects the city with the train station. Historically, this is because the Northeast Corridor in New Jersey is a then-high-speed rail cutoff from 1863, which cut off Princeton from the old line. Trains run back and forth, with timed connections between New York (but not Trenton) and Princeton.

The Princeton stop on the Dinky, as can be seen in the satellite image, lies just outside the historic municipal limits of Princeton (since merged with the surrounding township). It serves the university fairly well, but is 800 meters at closest approach to the town’s main street, Nassau Street. So there has been a study for what to do to improve city access, in which a tram-train option was studied, looked good, and was dropped anyway. There are two options left: status quo, and a downgrade of the right-of-way to light rail with buses using the same corridor.

Unfortunately, transit advocates I respect, like Sandy Johnston, think the downgrade is an upgrade. So let me explain why in fact the light rail and bus option is inferior to current commuter rail operations.

The current use of the Dinky is as a connector to the Northeast Corridor. There is approximately nothing else at Princeton Junction: it’s one of the two busiest suburban stations in New Jersey, but like the other top station, Metropark, it’s a park-and-ride, designed exclusively for car-train interface. People who ride the Dinky do so to get to New York.

This means that the timed transfer with the mainline trains is critical. Frequency on the Dinky is irrelevant: all ridership from Princeton Junction into the town is going to be on the first train or bus after the mainline trains arrive, and almost all ridership to the junction is going to be on the last train that makes the connection. While frequency is not important except insofar as it matches that of the mainline, on-train capacity is important. My 2015 recollection is that off-peak ridership on the Dinky is maybe enough to fill an articulated bus (which New Jersey Transit only runs in Newark), maybe enough for a standard bus, depending on time of day – standees are likely, and standing on a bus is an awful passenger experience. At rush hour, the Dinky runs three-car trains (update 2022-2-18: no, it’s two-car trains) and they’re full.

The timed transfer is so important that the discussion of how to improve service must center how to make the transfer more efficient. The ideal improvement should be to regularize the timetable on the mainline commuter trains, and ensure that trains in opposite directions serve Princeton Junction around the same time (this is called a knot) so that the Dinky can connect to Trenton too, and even to Philadelphia with another timed transfer at Trenton or even through-service if that fits the New Jersey Transit and SEPTA schedules.

Sandy points out to me that while the Dinky only connects Princeton with the mainline, the right-of-way of the Dinky can serve more destinations – namely, the Route 1 job cluster, visible on the map as a line of office parks.

However, bus service from town to Route 1 is unlikely to succeed. It’s going to struggle to run sufficient frequency for what it needs, even as lower-frequency rail is sufficient for the Dinky’s current role:

  • Route 1 is not on the way between town and the station – there would have to be separate buses to Route 1 from the service to the train station (which I presume will stay on rail even if the downgrade is picked). This means there’s no bundling of destinations – the buses to Route 1 have to live off of Princeton-Route 1 trips.
  • Route 1 is a freeway with destinations located somewhat away, at automobile scale. Buses can stop on the side of the road but the walk is not great on the same side of the road and hostile and unsafe if crossing the road is required. A more pleasant experience is only possible if buses turn onto side roads, splitting frequency or increasing trip times.
  • Route 1 is not a large job center. OnTheMap says that between the route of the Dinky and the junction with I-295 beyond the above satellite image, which ends at Quakerbridge Road, there are 21,000 jobs. The origins of those jobs are dispersed – only 5,000 come from within the county, and only 368 come from within Princeton.
  • Conversely, the short distance traveled means that high frequency is crucial. A one-way trip from the townhouses just north of Nassau Street to the center of the Route 1 cluster along the right-of-way of the Dinky is 5.5 km, which at BRT and freeway speed is around 10 minutes one-way; a bus running less than once every 10 minutes might as well not run – but there is no chance for such a bus to fill at current demand.

Of course, the analysis of Route 1 assumes current development patterns stay with no or moderate change. A bigger change, such as greater development along Route 1 with sprawl repair, can make this option pencil out; O&D volumes need to rise by a factor of 3 assuming 100% transit modal split, or more if modal split is lower (which it invariably is, Route 1 is not Manhattan).

But then that raises the question – why engage in development in sprawl around a plan to downgrade a rail service?

If sprawl repair is plausible, then make Princeton more bikable and then set up bike lanes on Route 1 so that people can cycle to Route 1 jobs. The same bike lanes can also connect to the Dinky, with bike parking at the station, or even potentially at Princeton Junction if it’s faster to bike those 4 km than to ride a train and transfer. In the long run, all buses are going to have to be replaced by bikes anyway – bus operating costs are only going to go up.

And if redevelopment is plausible, look again at the satellite image and see what the land use at the existing train stations is like. Princeton is one of the most expensive places in the United States, and the Dinky station has a golf course on one side; that’s 0.5 km^2 of land, or, as I prefer to think of it, 50,000 housing units. Another 0.05 km^2 consists of parking lots right near the station, and can and should be redeveloped as a town center extension for a population that can swamp the existing town population by a factor of 4. The parking lots at Princeton Junction and the undeveloped land between them are another 0.4 km^2 of prime real estate.

In general, I cannot think of any railway where service would be improved by a downgrade from mainline rail to bus. But the Dinky has specific issues making such a downgrade especially deleterious for current users, namely the need for a timed connection, while the proposed source of new trips, namely Route 1, is too weak to be worth much. Thankfully, a no-build option keeping the status quo is still under consideration, and I hope that the region chooses it and invests in making the Dinky better rather than in replacing it.


  1. James S

    A few notes:
    “Frequency on the Dinky is irrelevant”
    As you note later, this isnt true. Connections are timed for NYC trains and ONLY NYC trains. Anyone coming or going to Trenton and Philly gets absolutely destroyed by the arbitrary 30+ minute waits on a line could come every 15 minutes. The rest of the time the driver is reading the newspaper.

    “At rush hour, the Dinky runs three-car trains and they’re full.”

    Not anymore. When they moved the station further from town (a top tier idiotic decision) the line was bustituted for awhile for the construction, and ridership never recovered. And then a year or so later, NJT was having major labor shortages and guess which line was first to be cut? The dinky was basically shut down again in 2018. And now post-COVID you can imagine ridership is even worse.

    I think whats missing is that a change to light rail means an isolated vehicle with isolated maintenance needs. Isnt NJT getting new bi-level EMUs? Use one of those.

    NJT has much better uses of capital money, such as the long-delayed HBLR extension, the Glassboro Light Rail, and Monmouth rail. It makes no sense to spend any time on the Dinky. Run it more frequently using the same current train and/or a newer EMU model. And thats it.

  2. adirondacker12800

    Princeton is one of the most expensive places in the United States,

    Which is why they are building the TOD other places. There are lots of places in New Jersey that aren’t near an Ivy League university.

  3. adirondacker12800

    through-service if that fits the New Jersey Transit and SEPTA schedules.

    NJ Transit runs long multilevels. SEPTA runs short single levels. I doubt there will ever be demand south/west of Trenton for that much capacity. Which I’ve pointed out more than once.

    NJTransit and Amtrak analyzed passengers using Trenton and Hamilton. Many many years ago. A bit more than half of them were Pennsylvanians going to Manhattan. If someday far far in the future, when Gateway opens, SEPTA wants to run a train that runs local between Philadelphia and Trenton that stops at Princeton Junction, perhaps New Brunswick and Newark ( for Wall Street ) they can. Get all the Pennsylvanians going to New York off the New Jersey trains that leaves space for New Jerseyans. Only the extraordinarily frugal are going want to use that train to get from New York to Philadelphia.

    • Eric2

      NJT/SEPTA interlining is indeed unimportant, what’s important is fare integrating both of them with Amtrak so that you can take Amtrak to Trenton and switch to a local train to your stop on the far side of Trenton.

      • adirondacker12800

        I don’t know why it’s such a hurdle to use a TVM twice in a trip. Or have two things on your smartphone.

        • Eric2

          The point is that Amtrak costs about 10x as much as the others so normal people can’t afford to use the TVM once for Amtrak and once for SEPTA/NJT.

          • adirondacker12800

            You don’t have much of a choice if the station doesn’t have Amtrak service. You do understand that there are Acela trains and, Regional trains. Metro North, NJTransit and SEPTA have local and express service.
            Just for giggles I asked what the Amtrak fare is between NY Penn Station and 30th Street Philadelphia. For dates in April it’s $18 on a Regional and 1:23. It’s $22.60 with two changes on NJTransit. ( NEC train to Trenton, River Line to Pennsauken and Atlantic City Line to Philadelphia. ) and a trip time of 3;21. If you were feeling especially masochistic you could take PATH from Herald Square, change in Journal Square to a Newark train and get on NJTransit there.
            It’s $25 if you want to use SEPTA’s Trenton line trains from Trenton. If you are a regular SEPTA user and have a card. More if you don’t.

      • Andre

        That used to be how it worked with Clocker service (which ran a limited service between Philly and New York) and NJT fares, but then Amtrak got sick of all their passengers being NJT riders and offloaded the service onto NJT’s express trains.

    • Alon Levy

      Yeah, that’s why I said “if.” If it just doesn’t work out with SEPTA train lengths, then time the connection at Trenton.

      • adirondacker12800

        You didn’t say train length. You said “schedules”. SEPTA doesn’t have significant capacity constraints, They could time the trains. If there are whole trainloads of Pennsylvanians boarding trains in New Jersey, there can be SEPTA or LANTA or LCTA/NEPA trains to New York.

  4. df1982

    “In the long run, all buses are going to have to be replaced by bikes anyway – bus operating costs are only going to go up.”

    Is this a serious comment? Even if it was possible for the able-bodied, it would leave a lot of the elderly, disabled, parents with young children, etc. in the lurch. Given your earlier posts about accessibility, it appears pretty callous.

    • Henry Miller

      It is sadly reality. We need to figure out how to build automated systems very cheaply to get around it. Or maybe how to move elderly/disabled people close to transit stops while more able bodied people get to live farther out. Or a breakthrough in medical? Or finally get self driving buses? Whatever the reality is buses are too expensive and solutions are not easy.

      • df1982

        By what measure are they “too expensive”? Surely this is dependent on a) revenue from ridership and b) how much a society values the service such that it is acceptable to provide a subsidy for it.

        It’s true that short of fully automated buses there is little room for increases in labour productivity per bus km travelled (since you can’t have 0.9 people driving a bus). But there are any number of measures that can be taken to improve productivity through maximising the utility of the service per bus km travelled, many of which are discussed here and in other transport forums, and which US transit agencies are far from having exhausted (to put it mildly).

        In any case labor costs are not increasing at such an astronomic rate that providing bus service will become prohibitively expensive in any foreseeable timeframe.

      • Sassy

        There’s a great automated transit system that is fairly affordable in the grand scheme of things. It’s called the elevator.

        Getting old people out of 2 story houses with stairs and into towers where they can freely roam their stair free unit, and out of spread out neighborhoods where they might be tempted to drive (which must be absolutely unacceptable from a safety standpoint) and into neighborhoods walkable at even slower speeds, would even represent a major quality of life improvement.

    • Alon Levy

      I know, it’s a serious problem depending on the disability (Dutch standards are supposed to be usable by the average 60-year-old, but 80 > 60), but bus operating costs keep rising and if driverless operations don’t work out it’s going to be unaffordable at some point.

      • df1982

        When is “at some point”? This side of 2100? It’s really not something any transit activists should be worried about. The opposite in fact: the easiest way to quickly scale up transit in car-dominated cities is through frequent bus service in bus lanes.

        • Henry Miller

          I agree right now cities should be buying many buses (and getting many more drivers – getting enough drivers means they need to raise pay because of supply/demand – getting to your when question). As you say, a bus is the fastest, easiest way to get more transport in a city now. However all those routes should be created with the idea that they are trying to prove people will ride, and once people are riding they will vote for even better transports. People who ride the bus are more likely to agree to putting an automated train in, and in the long run that automated train is a lot cheaper. However it takes years to build the train and then you need to get people to ride it (something the bus is good for – if people are riding the bus they will switch to the train when it opens)

          Of course if automating driving ever happens maybe the right answer is driverless buses. 10 years ago I predicted that it would be illegal to make a non-automated car today – clearly my prediction skills are wrong. I’m not making any more predictions. Cities should for sure watch driverless technology, it is worth buying some driverless bus as soon as they come out even if the manufacture puts limits on how they can be used – buying technology will encourage investment and this is something all bus cities need.

          Until we have driverless buses investing in automated trains is the right thing for cities. Once we have driverless buses we can discuss where a bus vs train is the right answer. Or maybe some other technology?

          • Matthew Hutton

            Automated cars still have almost all of the negative externalities of standard cars – and actually risk making them worse with more night driving etc.

          • df1982

            Driverless cars will always be 5-10 years away. It’s not that they’re technologically unfeasible, it’s that they’re socially unworkable. The only exception would potentially be on grade-segregated highways: you drive the car onto the highway, set it on autopilot and take the wheel again at the off-ramp. But anything that mixes with a human environment will require a human driver unless we radically change our concept of how cities function (and I for one would not be willing to do that for this particular cause).

            Automated buses are perhaps more feasible (running in reserved bus lanes rather than mixed traffic). There are already low-speed examples, the challenge is doing it safely at 50-60km/h. of course you can invest in driverless trains, but they’re not the solution for everything, you’ll always need a tier of a public transport serving corridors where the ridership doesn’t justify the expense of rail infrastructure.

  5. Michael Finfer

    Ridership on the dinky just before and just after breaks at the University is much heavier than you suggest. Many of the students, most of whom don’t have cars, use the train to get to or from the University at those times. I doubt that buses can handle the demand well.

  6. SC

    Just an FYI, the section of Route 1 through Princeton Junction is technically not a freeway. It is historically a colonial-era corduroy road: https://www.loc.gov/item/73691816/

    Also, I’m surprised you did not note that the Dinky station was moved further from the center of town, not because NJT wanted to spend capital money to do so, but because Princeton University itself instigated the move as part of its campus master plan to capture more space for its arts programs. The Princeton Dinky station move was paid with funds from the Princeton University endowment, wealthy donors, and student tuition. It’s a bad case of how the power that comes from wealth and money affects urbanism.

    Lastly, most of the jobs NJT hopes to serve on the Route 1 corridor is not within the 1/2-mile walkshed of the proposed Route 1 station. The jobs stretch down a 7-mi linear corridor from Quakerbridge mall to the south up to the Dow Jones campus at the north end, inclusive of the Carnegie Center office complex, the MarketFair mall, Princeton Hospital, and the Forrestal Campus office complex. This section of the roadway is heavily congested, limited in ROW, and has additional potential for induced transit demand once a starter transit service is implemented.

    • Alon Levy

      The jobs that I counted among the 21,000 are not within half a mile of any specific station; the boundaries I chose on OnTheMap are the creek, I-295, a fuzzy boundary to the east (it’s single-family housing in that direction), and the Dinky, so it’s an elongated route as you point out. The origins of those jobs are so dispersed that local transit is never going to work. If anything, something that could work is buses from Princeton Junction timed with the train, but even those are going to be just for urban reverse-commuters who chose not to own a car.

  7. SB

    Why should route 1 corridor be chosen for TOD over Nassau street corridor in the first place?
    Nassau street is already walkable, I don’t think route 1 will ever be walkable.

  8. Borners

    Speaking of University towns and their stations. Cambridge in England built a new infill station in 2017, because Cambridgeshire is run by Yimbyish types. Alon is 50 million pounds (67 million US?) for an above ground 3 platform station atrociously expensive or hideously expensive?

      • Borners

        Nothing especially fancy except maybe stuff for their weird guided bus lane and a solar powered bicycle rack. Its East Anglia so its really really flat terrain.

        What would a cheap/global median-ish cost be?

        • Matthew Hutton

          If you want to know how cheaply Britain can/could build a simple railway station in the countryside relatively recently look up how much Haddenham and Thame Parkway cost to open in 1987.

  9. Princetonian

    While Princeton is among the least-used stations along the Northeast Corridor, it is among the busiest commuter rail stations in the country, adjacent to a major university and a few blocks from a walkable town center. (It is not convenient to the rest of the town.) Readers should know that, despite the distance from Manhattan, many thousands commute to New York from the Princeton area and surrounding Mercer County, and the Princeton station provides an important 4th point in the county to pick up train service.

    Some type of comprehensive Princeton bus service with lines that directly serve Princeton Junction would seem to work, but I believe that the catchment area is too spread out for this to work very well. A bus running every 5-10 minutes down Nassau Street and serving university stops and then going to Princeton Junction could work.

    What railcar will replace the Dinky when the 40-year-old Arrows finally kick the bucket?

    I believe slot times and operational constraints at Penn Station hinder any potential knot scheduling on the Northeast Corridor. If SEPTA and NJ Transit could ever better coordinate transfers at Trenton, then the Dinky should be run more often to connect to westbound NJ Transit trains at Princeton Junction.

    A historical detail: there have indeed been a few riders who use the Dinky just to travel from Princeton to the Junction. A man by the name of Albert Einstein, who worked at a local university, sometimes used to take the Dinky and sit and have lunch and watch/listen to the high-speed trains hurtle past at Princeton Junction. From this experience he developed his theory of relativity.

    • Tom M

      Hate to pop your bubble, but Einstein published his paper on Special Relativity in 1905 and General Relativity in 1915. He did not visit the US, let alone live there, until 1921.

      • Princetonian

        Darn it, I stand corrected. I must be thinking of some other someone. In any event, I think Princeton mathematician John Nash used to commute on the Dinky from the Junction to the university.

          • adirondacker12800

            Or they can just order two more of the hundreds of cars they run on other lines. Things that meet the level boarding platforms at the existing stations. And when it goes for regular maintenance it can be swapped with two other cars from someplace else. And the days of the year when university students are arriving or departing, run three cars.

          • Matthew Hutton

            Makes sense! I assumed that wasn’t possible for some reason 🙁.

          • adirondacker12800

            … well, it’s not clear from anything in the thread that it uses the same cars that can go anywhere between Sunnyside Yards in Queens and Washington D.C. or Harrisburg.
            NJTransit and SEPTA have options to order another 886 of these.
            They could be an alternative for MetroNorth’s Penn Station Access, MARC and the MBTA. It’s all got the same loading gauge and compatible signaling. The only things that would have to be different is the paint colors and upholstery.

  10. Nathanael

    Nobody seems to know why NJT has been attacking the Dinky for 30 years, but it has.

    The tram-train option, running as a tram right into downtown Princeton, was always obviously the right thing to do and almost happened — but then the municipality of Princeton was merged with the surrounding rural areas, so that the car-obsessed anti-transit rural voters could vote down the plan. Aaaargh.

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