# Track Capacity Questions



## Anderson (May 28, 2011)

This particularly applies to the PHL-NYP segment, but the question can be extrapolated to other parts of the NEC. Even assuming a new set of tracks goes in parallel to the existing ones for the super-duper HSR plan, what is the per-hour track capacity of a set of four RR tracks? Particularly in terms of higher-speed trains, I'd think that the capacity becomes static at some point, if not potentially falling off (any gains in moving trains faster get offset by needing more spacing to allow a train to stop in an emergency).

The question arises because I ran some back of the envelope calculations for Amtrak's long-term projections if they get their fancy new 220 MPH alignment put in: According to their stats, the south-of-NYC and through-NYC traffic totals would come to just under 30,000 passengers per day (on average) on the Regional trains and _another_ 30,000 the High Speed trains. Assuming 300 passengers per train on average (i.e. accounting for the fact that you can pack more folks into that 8:30 AM train than you'll get to sign onto the 9:00 PM one), you're rapidly closing in on 200 trains per day on a single alignment if the per-day average were to hold across every day...and more practically, probably closer to 250 trains per day on weekdays (but "only" 150-175 on weekends). Note, by the way, that this does not count in Keystone service trains (which probably throw another 10-20 on top of that), nor does it account for any NJ Transit trains that would be getting thrown into the mix.

The Hudson tunnels aren't the big issue in my mind...you can juggle scheduling there a bit better, particularly since it's just one segment. What's setting up trouble is once you get further down the line...can a single alignment of some sort take the sort of rush hour peak traffic that these figures imply, or would Amtrak _have_ to kick trains onto another alignment (further east or west) that "tags in" at Philadelphia? I ask about the south-of-NY traffic because Amtrak at least has some plans to split things north of NYP...but the southern end of things, in addition to having higher demand (albeit only marginally so under those projections), makes no plans to have a second alignment...which implies either some six-track behemoth or some other sort of rearrangement.


----------



## jis (May 30, 2011)

It all depends on the capabilities of the signaling system

The High Line between Newark and New York is currently designed to run 2 min headway at 90mph, that would be 30 tph, so in 10 hours you'd carry 300 trains if you were running full tilt, which of course in the course of a normal day you don't.

For 160mph a 4 min or so headway is not out of the question, If you have a 4 track railroad like the NEC between Newark and Philly you'd essentially have 30tph capacity on that. Actually since the outer tracks are actually lower speed you may have somewhat higher overall capacity. Also since a portion is 6 tracks that would also potentially add to the capacity.

But again, it depends a lot on the signaling system, operating patterns, frequency and nature of universal crossover, and a dozen other factors.


----------



## Anderson (May 31, 2011)

Thanks a bunch. What's worrying me is more the swarms of slower trains that seem to be part of the plans Amtrak has, not to mention that with (for example) 160 MPH trains, you're going to have major "demand bubbles" that I don't think the system can handle without some _really_ painful bucket system manipulation. I honestly get the feeling that these numbers haven't been seriously considered by anyone at Amtrak's offices...especially once you throw in steadily increasing NJTransit traffic, which Amtrak _is_ projecting numbers on. Yes, there are some places you _might_ be able to throw in dedicated extra tracks, and Amtrak could at least theoretically throw what little freight crosses their tracks off (though I think that runs overnight and so isn't part of the equation anyway), but you're still going to run into limits at the big rivers almost no matter what: I just can't see some massive eight-track alignment crossing the Susquehanna (not that the squeeze is there), and I don't know if you can really get benefits out of too many extra tracks.

The High Line is almost assuredly _the_ chokepoint for any of this: Going with Amtrak's NJTransit projections, I think they're estimating over 500 trains/day on the entirety of the High Line (100 Amtrak and 400-odd NJT), with even more breaking off just past Secaucus. With that, you'd need 4 tracks running with 2-minute separations non-stop for about ten hours to even get _close_ to the projected numbers...and I think we all know that you can't fill the 10:30 AM commuter train the same way you can fill the 7:30 AM one. Add to that the implied 100 or so additional Amtrak trains that the HSR vision suggests...I think the High Line might have to go to six tracks (in some form...a split alignment of some kind might also have to happen) just to keep up with those numbers.


----------



## jis (May 31, 2011)

Anderson said:


> The High Line is almost assuredly _the_ chokepoint for any of this: Going with Amtrak's NJTransit projections, I think they're estimating over 500 trains/day on the entirety of the High Line (100 Amtrak and 400-odd NJT), with even more breaking off just past Secaucus. With that, you'd need 4 tracks running with 2-minute separations non-stop for about ten hours to even get _close_ to the projected numbers...and I think we all know that you can't fill the 10:30 AM commuter train the same way you can fill the 7:30 AM one. Add to that the implied 100 or so additional Amtrak trains that the HSR vision suggests...I think the High Line might have to go to six tracks (in some form...a split alignment of some kind might also have to happen) just to keep up with those numbers.


The HSR Vision trains won't be on the High Line. They will be in the visionary 11 mile long tunnel.

4 tracks from Newark to New York with 2 mins headway will suffice for a long long time. Amtrak and NJT's projections will eventually come down to reality, which currently they are not particularly attached to. They are based on early decade population and demographic projections. Since then all numbers have beenr evised and they are all unformly downwards 5% or more from the earlier stratospheric ones.

There will never be a need for an 8 track bridge across the Susquehanna. Four tracks will suffice for a long long time. The population trends are that they are moving south. population growth in the NEC area is going to be small to moderate. Where does Amtrak think it will get all these riders from? Does anyone believe that fares will actually go down as gas prices and in tandem with it general energy prices keep going up?

Currently the NEC is very inefficiently signaled with huge freight sized blocks and very infrequent crossovers. There is much that can be fixed to enhance capacity before one needs additional tracks. And of course, of necessity the tracks for any HSR with speeds higher than 160mph will be separate from the currently existing ones, since they will require significantly greater track center separation than what is obtained on the NEC today. So there you have two extra tracks anyway most of the way.


----------



## Anderson (May 31, 2011)

jis said:


> Anderson said:
> 
> 
> > The High Line is almost assuredly _the_ chokepoint for any of this: Going with Amtrak's NJTransit projections, I think they're estimating over 500 trains/day on the entirety of the High Line (100 Amtrak and 400-odd NJT), with even more breaking off just past Secaucus. With that, you'd need 4 tracks running with 2-minute separations non-stop for about ten hours to even get _close_ to the projected numbers...and I think we all know that you can't fill the 10:30 AM commuter train the same way you can fill the 7:30 AM one. Add to that the implied 100 or so additional Amtrak trains that the HSR vision suggests...I think the High Line might have to go to six tracks (in some form...a split alignment of some kind might also have to happen) just to keep up with those numbers.
> ...


I don't think Amtrak _needs_ fares to come down...it just needs them to come down _in relation to_ other modes of travel, and/or congestion on those modes to get worse.

Let's throw dollars out and substitute a new currency unit: The gallon (of gas). If gas is $3 a gallon and a given Amtrak ticket from NYP-WAS costs $90, then it costs 30 gallons to go from NYP-WAS. If gas goes to $5 and the Amtrak ticket goes to $100, the Amtrak ticket costs 20 gallons. Dollars and cents are simply a convenient way of comparing items without having to barter directly.

My point is that if Amtrak fares don't track gas prices on the way up on the NEC, you start hitting major price break points sooner or later...and I think that's coming sooner rather than later on some of those big routes. As it stands, you're already there on NPN-RVM and some other short hauls (particularly well-subsidized ones...I think PHL-HAR is also getting there, for example)...the main spine isn't there, but you're starting to reach tipping points with airline tickets in a number of markets. I would also point out in response to any arguments that price increases will wash this out for Amtrak (that is, they'll hike the buckets to compensate) that at some point, the route flips _hard_ into the black and Amtrak starts being able to pay for new Regional equipment a la the new Acelas.

Though I think the report doesn't say as much, I see the increased demand coming not from increased population, but because of competitive disadvantages of other forms of transport in the Northeast over the long haul.


----------



## jis (May 31, 2011)

There will be increased demand, but nothing even close to what Amtrak says it is basing its projections on. That is sheer fantasy to try to support a project. NJT did the same with the demand projections for ARC, and the North jersey TPA, in the heady days of the bubble agreed with their projections back then. Their new revised numbers don;t agree with the projections made back then. About a month back we had a meeting with some folks from the New York Metropolitan Transportation Council (the local TPA which must approve all transportation expenditures in its area of control in order for said projects to get federal funding) and I was floored to discover that even they don't agree with Amtrak's projection of economic activities in the New York region that its ridership projections are based on! So there is a much tougher road to hoe than is being let on by the likes of Amtrak.


----------

