The Value of Modern EMUs
I do not know how to code. The most complex actually working code that I have written is 48 lines of Python that implement a train performance calculator that, before coding it, I would just run using a couple of Wolfram Alpha formulas. Here is a zipped version of the program. You can download Python 2.7 and run it there; there may also be online applets, but the one I tried doesn’t work well.
You’ll get a command line interface into which you can type various commands – for example, if you put in 2 + 5 the machine will natively output 7. What my program does is define functions relevant to train performance: accpen(k,a,b,c,m,x1,x2,n) is the acceleration penalty from speed x1 m/s to speed x2 m/s where x1 < x2 (if you try the other way around you’ll get funny results) for a train with a power-to-weight ratio of k kilowatts per ton, an initial acceleration rate of m m/s^2, and constant, linear, and quadratic running resistance terms a, b, and c. To find the deceleration penalty, put in decpen, and to find the total, either put in the two functions and add, or put in slowpen to get the sum. The text of the program gives the values of a, b, and c for the X2000 in Sweden, taken from PDF-p. 64 of a tilting trains thesis I’ve cited many times. A few high-speed trainsets give their own values of these terms; I also give an experimentally measured lower air resistance factor (the quadratic term c) for Shinkansen. Power-to-weight ratios are generally available for trainsets, usually on Wikipedia. Initial acceleration rates are sometimes publicly available but not always. Finally, n is a numerical integration quantity that should be set high, in the high hundreds or thousands at least. You need to either define all the quantities when you run the program, or plug in explicit numbers, e.g. slowpen(20, 0.0059, 0.000118, 0.000022, 1.2, 0, 44.44, 2000).
I’ve used this program to find slow zone penalties for recent high-speed rail calculations, such as the one in this post. I thought it would not be useful for regional trains, since I don’t have any idea what their running resistance values are, but upon further inspection I realized that at speeds below 160 km/h resistance is far too low to be of any consequence. Doubling c from its X2000 value to 0.000044 only changes the acceleration penalty by a fraction of a second up to 160 km/h.
With this in mind, I ran the program with the parameters of the FLIRT, assuming the same running resistance as the X2000. The FLIRT’s power-to-weight ratio is 21.1 in Romandy, and I saw a factsheet in German-speaking Switzerland that’s no longer on Stadler’s website citing slightly lower mass, corresponding to a power-to-weight ratio of 21.7; however, these numbers do not include passengers, and adding a busy but not full complement of passengers adds mass to the train until its power-to-weight ratio shrinks to about 20 or a little less. With an initial acceleration of about 1.2 m/s^2, the program spits out an acceleration penalty of 23 seconds from 0 to 160 km/h (i.e. 44.44 m/s) and a deceleration penalty of 22 seconds. In videos the acceleration penalty appears to be 24 seconds, which difference comes from a slight ramping up of acceleration at 0 km/h rather than instant application of the full rate.
In other words: the program manages to predict regional train performance to a very good approximation. So what about some other trains?
I ran the same calculation on Metro-North’s M-8. Its power-to-weight ratio is 12.2 kW/t (each car is powered at 800 kW and weighs 65.5 t empty), shrinking to 11.3 when adding 75 passengers per car weighing a total of 5 tons. A student paper by Daniel Delgado cites the M-8’s initial acceleration as 2 mph/s, or 0.9 m/s^2. With these parameters, the acceleration penalty is 37.1 seconds and the deceleration penalty is 34.1 seconds; moreover, the paper show how long it takes to ramp up to full acceleration rate, and this adds a few seconds, for a total stop penalty (excluding dwell time) of about 75 seconds, compared with 45 for the FLIRT.
In other words: FRA-compliant EMUs add 30 seconds to each stop penalty compared with top-line European EMUs.
Now, what about other rolling stock? There, it gets more speculative, because I don’t know the initial acceleration rates. I can make some educated guesses based on adhesion factors and semi-reliable measured acceleration data (thanks to Ari Ofsevit). Amtrak’s new Northeast Regional locomotives, the Sprinters, seem to have k = 12.2 with 400 passengers and m = 0.44 or a little less, for a penalty of 52 seconds plus a long acceleration ramp up adding a brutal 18 seconds of acceleration time, or 70 in total (more likely it’s inaccuracies in data measurements – Ari’s source is based on imperfect GPS samples). Were these locomotives to lug heavier coaches than those used on the Regional, such as the bilevels used by the MBTA, the values of both k and m would fall and the penalty would be 61 seconds even before adding in the acceleration ramp. Deceleration is slow as well – in fact Wikipedia says that the Sprinters decelerate at 5 MW and not at their maximum acceleration rate of 6.4 MW, so in the decpen calculation we must reduce k accordingly. The total is somewhere in the 120-150 second range, depending on how one treats the measured acceleration ramp.
In other words: even powerful electric locomotives have very weak acceleration, thanks to poor adhesion. The stop penalty to 160 km/h is about 60 seconds higher than for the M-8 (which is FRA-compliant and much heavier than Amfleet coaches) and 90 seconds higher than for the FLIRT.
Locomotive-hauled trains’ initial acceleration is weak that reducing the power-to-weight ratio to that of an MBTA diesel locomotive (about 5 kW/t) doesn’t even matter all that much. According to my model, the MBTA diesels’ total stop penalty to 160 km/h is 185 seconds excluding any acceleration ramp and assuming initial acceleration is 0.3 m/s^2, so with the ramp it might be 190 seconds. Of note, this model fails to reproduce the lower acceleration rates cited by a study from last decade about DMUs on the Fairmount Line, which claims a 70-second penalty to 100 km/h; such a penalty is far too high, consistent with about 0.2 m/s^2 initial acceleration, which is far too weak based on local/express time differences on the schedule. The actual MBTA trains only run at 130 km/h, but are capable of 160, given long enough interstations – they just don’t do it because there’s little benefit, they accelerate so slowly.
Unsurprisingly, modern rail operations almost never buy locomotives for train services that are expected to stop frequently, and some, including the Japanese and British rail systems, no longer buy electric locomotives at all, using EMUs exclusively due to their superior performance. Clem Tillier made this point last year in the context of Caltrain: in February the Trump administration froze Caltrain’s federal electrification funding as a ploy to attack California HSR, and before it finally relented and released the money a few months later, some activists discussed Plan B, one of which was buying locomotives. Clem was adamant that no, based on his simulations electric locomotives would barely save any time due to their weak acceleration, and EMUs were obligatory. My program confirms his calculations: even starting with very weak and unreliable diesel locomotives, the savings from replacing diesel with electric locomotives are smaller than those from replacing electric locomotives with EMUs, and depending on assumptions on initial acceleration rates might be half as high as the benefits of transitioning from electric locomotives to EMUs (thus, a third as high as those of transitioning straight from diesels to EMUs).
Thus there is no excuse for any regional passenger railroad to procure locomotives of any kind. Service must run with multiple units, ideally electric ones, to maximize initial acceleration as well as the power-to-weight ratio. If the top speed is 160 km/h, then a good EMU has a stop penalty of about 45 seconds, a powerful electric locomotive about 135 seconds, and a diesel locomotive around 190 seconds. With short dwell times coming from level boarding and wide doors, EMUs completely change the equation for local service and infill stops, making more stops justifiable in places where the brutal stop penalty of a locomotive would make them problematic.
This all seems pretty much what has always been true, EMUs accelerate faster than locomotive hauled trains. I might add that in Japan the switch to EMUs in the 1950-60s by JNR was done in part place less stress on the track compare to locomotive hauled express trains, thus reducing maintenance.
To throw in a curve-ball, what about the UK’s new Class 800 Intercity Express Train? These are “electro-diesels” (dual-modes) and thus have the weight of diesel engines and fuel added to the electric motors. I have read in ‘Modern Railways’ that while the Class 800 DEMUs get started faster than the Intercity 125 HSTs they are replacing, once it gets up to speed the HSTs out perform the Class 800 train-sets.
I try not to think about British railways outside London. It’s like how I try not to think about anything in the United States outside New York, which unfortunately doesn’t always work.
There was a brief description in an article on Japan Railway and Transportation Review about the application of light-weight EMU to intercity express service in Japan:
Conventional Line Speed Increases and Development of Shinkansen (JRTR 57):
Click to access 42-49web.pdf
There was also a series of articles written by Masao Saito, an experienced railroad engineer (or former president of Tokyo Monorail Co., Ltd.), on Tetsudo Journal which covers the same topic in more detail.
Rail car/EMU weight reduction to reduce damages to tracks and to increase power-to-weight ratio at the same time was the one of the key principles behind of the speed improvements happened in Shinkansen system after the privatization of JNR, or development of 300 Series Shinkansen EMU. A part of this article talks about it:
Part 2: Speeding-up Conventional Lines and Shinkansen (JRTR 58):
Click to access 51-60web.pdf
At low speeds, tractive force is what counts, and in this case, the Class 800 has more driven axles than a HST. The higher the speed, the more power counts, and (comparing the diesel part of the Class 800 with the HST), the Class 800 starts to run short on steam, whereas the HST with something like 3 to 4 times the power can continue to speed up. Of course, the Class 800 in electric mode will beat a HST over the whole speed range.
On the northeast corridor in New Jersey we’ve seen this reality lived out in the decline in speeds due to the introduction of the double-decker coaches replacing EMUs. Comparing timetables gives you 58 minute trips becoming 72 minutes. The local trains from Princeton Junction now run typically over 80 minutes to Penn Station. These kinds of technological issues are invisible to the public, and evidently to those who run NJ Transit. Thanks for continuing to beat this drum on electrification and the need for the right rolling stock Alon.
I didn’t mention it in the post, but bilevels also add to the dwell time, especially if the doors are as fucked up as on the MBTA.
Everyone loved the bilevels when they where introduced but I’d never given a thought to the question of dwell time. It’s interesting that reading the 1926 rapid transit proposal for New Jersey, which included electrifying 399 miles of steam railroads and delivering them through a tunnel loop in Manhattan, there’s this quote:
“All under-river tunnels and all underground portions of the line will be constructed large enough to accommodate standard steam railroad equipment so that electric locomotives may haul commuter trains and standard steam trains around the loop pending the electrification of the suburban lines, after which it is assumed that multiple-unit equipment will be used.”
As far back as 1926 EMUs were assumed to follow with electrification. You also see that in the rolling stock choices of the Reading, Lackawanna, and Pennsylvania railroads for their electrified commuter lines.
Link to said study?
Interesting, so the estimate in 1926 was that they could haul 35 trains per hour per direction?
That is one of many cockamamie plans. There was the proposal to have a Union Station on Ninth Avenue someplace in the 50s and a ten track bridge across the Hudson. The railroads other than the Pennsylvania didn’t want to help pay for it. The Hudson and Manhattan was a rip snorting success, they got as far as drawing up blueprints for wedging four tracks into Jersey City. Then the Holland Tunnel opened. There was a serious faction in the PRR who proposed sending trains to Manhattan through Staten Island, Brooklyn and then up Fourth Avenue to the proposed new Grand Central. And use Park Ave to get to Woodlawn and the New Haven for service to Boston. For a short while trains from Boston got on a car float in the Bronx and got ferried to Jersey City for service to Washington. And there was service via Poughkeepsie between Boston and DC, for a short while. The LIRR was deeply fascinated by Far Rockaway. For a short time there were three ways to get there. All sorts of cockamamie plans.
They went and added Secaucus and Newark Airport. And Midtown Direct. And lowered the speed limit on Portal Bridge. The slow trains between Newark and New York were scheduled for 15 minutes, now it’s 20. A multilevel, on average holds 25 percent more passengers than an Arrow. If ARC was nearing completion they could be considering more Arrows. It isn’t, they can’t. And would have cut dwell time in Newark because all those Raritan Valley line passengers clogging the doors would be on a train that goes to New York.
The NEC is also likely to be the last place that NJT deploys their new MLV EMU’s, because of the punitive Amtrak electric rates on the south-of-Sunnyside NEC where they have a monopoly on electric transmission. Those long Trenton consists are far more costly to run on multiple units vs. push-pull with the terrible deal NJT is getting from Amtrak. The new cars are going to end up being gerrymandered to the North Jersey Coast Line and Morris & Essex Lines first because NJT’s homegrown electrification conforms to saner local-grid market rates (like the north-of-Sunnyside NEC does) vs. AMTK/Safe Harbor-sourced 25 Hz territory. And that’s not a self-limiting concession they’d do out of total lack of self-awareness, either. If it weren’t an ugly loss leader situation with the Amtrak rates I’m sure they’d much prefer to chuck the EMU’s at the NEC first for sheer schedule management sanity. Unfortunately you’re likely to get the opposite: NEC as dumping ground for reassigned ALP-46’s emptied off the other lines. Maybe with a few more rush hour double-drafts assigned for somewhat more pep on the longest, most sardine-can consists…but still with one hand effectively tied behind backs by Amtrak.
There seems to be news that Metro North is not going to buy any M-9’s as part of the once considered to be joint order with LIRR for same. Talk suggests that their interests viz a viz new passenger cars, if any, lie with bi-level locomotive hauled coaches along the lines of NJT offerings. [Sometimes I see bi-level and sometimes MLVs (MultiLevelVehicles?) and I don’t know the intended distinction and so don’t know which usage is appropriate for what, so pardon me if I am misusing them.] Presumably, this applies only to the NYS portion of MN.
All well and good if this is a plan only for the diesel territories above Croton-Harmon, but if this plan includes electric territory, then it would seem to be ill advised in light of your post, as the electric territories have close stop spacing.
I have also heard some talk that these Bombardier coaches were being designed in some sort of modular fashion allowing for them to be configured as EMU’s instead of unpowered coaches in either 3rd rail or overhead variations (don’t know about both, or what variations of electric power were covered, but that would probably not be a factor to MN in any case).
All of this stuff was, of course supposed to be able to fit into the Park Ave. tunnel and GCT.
Heard about this; any additional thoughts?
MNRR’s M9’s are subject to some paper games on the financing as they seek a better deal, but it’s inconceivable that they’ll back out entirely. Those cars are already being produced while NJT’s MLV EMU’s have only been RFP’d and won’t actually be awarded a bid until later this year. A cancellation of their M9 order would push out replacements by 2-4 years and cause them to have to budget for a much more intensive M3 systems renewal program than they’ve currently budgeted for. Unless there’s a reciprocal move to lengthen the M3’s stay on the system, don’t believe any of the hype about an M9 “cancellation”. It’s just the noise of paper shuffling and trying to drive a better bargain with Kawasaki on the far option end of that sprawling contract.
They did at the very beginning evaluate the prospect of going solo with an order of bi-level third rail EMU’s before the M9’s were going out to bid. Those would have potentially fit inside of the NJT MLV EMU packaging, merely being done up with DC third rail inputs instead of AC pantograph. But the price scalability of a huge common M9 order with LIRR was too much superior, so they never gave it serious thought. LIRR, of course, can’t use bi-level EMU’s of any kind because the dimensions of East Side Access conform to an M7/9 only with not an inch to spare (not even an M8 with its roof-mount resistors will fit).
MNRR is planning to go all bi-level with the diesel coach replacements, which are to be in a common order with LIRR to simultaneously replace all Shoreliners and East-of-Hudson Comets + the LIRR C3’s with a common make. The new bi will conform to the same 14’6″ NJT MLV dimensions, as borrowed NJT sets have already been clearance-tested into GCT in non-revenue service. So for all practical purposes “bi-level = MLV” when you’re talking anything New York. Taller 48-inch boarding bi’s like the MBTA’s and MARC’s K-cars are a whole foot too tall for New York. Coach procurement has not been funded yet because they can’t affix coach quantities until they are near-ready to move forward with the joint MNRR/LIRR/NYSDOT-Amtrak procurement of new dual-mode locomotives, and be able to project based on the loco order how many above-and-beyond coaches they’ll need to bank as consideration for running Penn Station Access off the Hudson/Empire Connection.
Reason it’s going to be bi’s and not flats-for-flats for the diesel procurement is that the Upper Hudson platforms are sitting at maximum car capacity for the most crowded trains, so lengthening consists will cause dwell delays as extra cars wouldn’t be able to platform. Also a creeping issue with some run-thru Upper Harlem trains, though not nearly to same degree as the Hudson. They calculated that opting for higher capacity cars would be a faster fix than commencing a mass platform lengthening program that would take years to wrangle with some of the NIMBY villages who have partial ownership stakes in a few of the ex-NY Central stations up there. While we won’t know until the RFP is issued what exact differences these coaches will have from the NJT MLV’s, the MTA likewise wants 2 x 2 and not 3 x 2 seating on them. Most likely will have a different vestibule door arrangement than the NJT cars, too, since both MTA roads are already 100% bi-level and don’t need to have the separate doors for level boarding -only vs. mixed boarding (may mean they opt for one bigger door in place of NJT’s smaller door pairs).
Not established yet if ConnDOT is going to join in with this MNRR/LIRR MTA coach procurement. They don’t inherently have as much to gain from it since few Danbury or Waterbury trains run thru to GCT, and they aren’t overspilling their platforms with the branch shuttle trains. Potentially they could have higher upside opting out (except for maybe a few bi’s for the GCT run-thrus) and instead transacting for all of the MTA’s Shoreliner III & IV cars displaced by this mass procurement. Those are the least-worn cars on the East-of-Hudson fleet, with >100 bodies to sift through…so picking the best-condition ones at scrap prices then budgeting for a light/moderate midlife overhaul might be a better ideal for CT. They could then use that uniform fleet of cars all equipped with middle doors to speed boarding on the Hartford Line, knocking out their crappy MBTA rentals for Hartford + ancient/smelly state-owned Shoreliner I’s & II’s for the branches + the current- Shore Line East/future- Hartford Mafersa coaches (few years older, won’t clear the GCT third rail, and creeping up on a go/no-go decision for midlife overhaul in a few years). Would lower maintenance costs for the uniformity, and could cheaply bank extras in storage for deep long-term Hartford + branch frequency expansion. Possibly with enough leftover to bid to MassDOT to run Springfield-Greenfield commuter rail on the Knowledge Corridor as a seamless Hartford Line service flavor (a.k.a. a “reverse Pilgrim Agreement” type setup akin to how the MBTA is RIDOT’s mercenary operator for intrastate service).
” They calculated that opting for higher capacity cars would be a faster fix than commencing a mass platform lengthening program that would take years to wrangle with some of the NIMBY villages who have partial ownership stakes in a few of the ex-NY Central stations up there”
They should have left the platforms short and said “your loss”
They are leaving the platforms short, they are solving the problem, in the short term anyway, by running trains with more capacity per car.
Unfortunately not that simple. The MTA’s in a world of hurt on raw ADA compliance (http://web.mta.info/accessibility/stations.htm#mnr) in ex- NY Central territory despite most Hudson/Harlem electric territory stations being full-highs for 75 years. Like LIRR (http://web.mta.info/accessibility/stations.htm#lirr) with its mass late-90’s platform raisings in diesel territory MNRR rammed through a lot of platform raisings for the 1984 Southeast electrification and in advance of their last major round of diesel fleet renewal on the Upper Hudson/Harlem. But note how many of those stops fail to achieve legal ADA compliance because the purely on-platform upgrades didn’t touch all else that was non-compliant with the stations. On MNRR the Harlem lags badly across the board. It doesn’t help that Westchester County is a bitch to negotiate with and 175 years of station ownership entanglements don’t give the MTA clean “Go screw off!” powers to unilaterally overrule the locals at holding hands when cross-ownership is involved. But that’s the legacy hand they have to play: dance with the local hamlets, or nothing gets done. It’s a worse inheritance situation for ex- NYC territory than what the New Haven Line got passed down from NYNH&H, where company control over stations was way tighter. But also not nearly as bad as the free-for-all on Long Island, where virtually NONE of the stations are fully ADA-compliant and virtually ALL of their 1998 diesel platform-raisings violate federal law due to the haste with which that program was administered.
Accessibility is just as big a problem for the two MTA commuter roads as it for NYCT. They have so many accessibility lawsuits filed and threatened to file against them, that engaging in another mass round of platform capacity construction before tackling the badly lacking egress accessibility at these stations is going to get them hit with a NY Supreme Court ruling to settle up at any cost or else. So for that reason you are not going to see mass lengthenings of 6-car Upper Hudson platforms to 8-10 cars commensurate with longer consists until they start getting their ADA act together on the Harlem and LIRR. You’ll be waiting the full lifespan of a coach procurement at the rate they’re going with that non-progress, so the procurement dept. is going to have to be the cog that makes the big capacity adjustment for the sake of Upper Hudson overcrowding…not Capital Construction.
You don’t have to like bi-levels per se to come to an acceptance that it’s probably the only move that situationally makes sense given the accessibility circumstances and timeframe for making any meaningful pivots before the ancient Shoreliner I/II’s and Comet II’s completely fall apart.
I don’t understand, how is accessibility related to platform length?
If you are in the first 6 cars, you can get off at this station. If you’re in the last 4 cars, you can’t. Doesn’t matter if you are in a wheelchair or not.
It relates to accessibility because the MTA won’t be able to initiate *any* station upgrade projects whatsoever unless first priority of those projects is settling up all non- ADA-compliant accessibility at those stations. Therefore, you will not see any platform lengthenings on the Upper Hudson/Harlem until the backlog of non-ADA stops is leaps-and-bounds tamed. Hudson Line has 4 non-compliant stations left out of 20 total covered under ADA, and Harlem Line a ghastly 15 non-compliant stations out of 25 total. That does not even count the several non-accessible limited-service stations on those lines and on the NY side of the border on the New Haven Line which aren’t legally considered out-of-compliance yet (emphasis on *yet*). The agency is going to get directed to spend funds on fixing the accessibility deficiencies on a majority of those cumulative 29 non-compliants in their jurisdiction before being allowed to spend on non-accessibility enhancements like increasing platform capacity on any one schedule.
The MTA, after all the legal threats, still isn’t budgeting much at all for systemwide accessibility compliance, so platform lengthenings for longer MNRR consists are going to be out of the question for a very long time. With a fish-or-cut-bait procurement decision on replacement push-pull coaches due in the next 3-4 year budgeting window, it’s a choice between finagling increased per-car capacity within the same consist length…or killing their own schedule management by ordering extra cars that won’t platform. The latter isn’t an acceptable option for maintaining service levels, so they’re choosing the former and adopting MLV’s. Non-platforming cars as regular service plan is also a net negative for aggregate systemwide accessibility at a time when the MTA is practically daring the courts to slap them hard with a cripplingly costly ADA compliance ruling…so poking the dynamite monkey with that service plan would’ve been a very unwise move to begin with.
The MTA used up all their “Go screw” leverage on station structures with the 25 years and multiple court rulings they spent sitting on their hands instead of advancing systemwide accessibility. Now all that wasted time is starting to seriously constrain their planning ability. Nobody’s fault but their own.
Curious how much this applies to high speed trains as opposed to regional trains. The world as a whole seems to be gravitating toward high speed EMUs but there are still at least a few locomotive-hauled high speed sets out there.
Not as much, since more (or most) of the time is spent at top speed. However, better acceleration can’t hurt, as there zones of reduced speed (any station, urban station approaches, designed slow zones, work zones, etc.) that need to be accelerated away from. But I think the main advantage of high-speed EMUs is that they allow for more revenue floor space. Also, a failure of a motor or entire truck (depending on the design) won’t have as much impact as the loss of a motor/truck in a loco-hauled design.
With distributed power, it is possible to design a highspeed line with steeper grades (such as for example Köln – Frankfurt), where distributed power is mandatory (only ICE-3 and other Velaro-types are allowed, but ICE-1 and ICE-2 are banned). More tractive force does not only mean better acceleration, but also better behavior in grades.
If the line has no serious grades, and the traffic density is not too high, loco-hauled sets do work reasonably well (such as TGVs or ICE-1/2 sets).
The Thalys, which competes with ICE on the Brussels-Cologne-Dortmund-Essen market, uses loco-hauled TGV-like trainsets. If they had EMUs they could also compete on the Frankfurt market. I don’t know if the Thalys board has any dreams of expansion, but maybe they should consider this when ordering new trainsets…
The LGV Sud-Est has 3.5% grades, but they’re short, so it’s fine if the train can’t accelerate up (except at very low speed) because it starts at the bottom of the hill at 300 km/h, so it’ll get to the top in a few seconds and only lose a few km/h. The reason the TGV sticks to power cars is that SNCF loves its bilevels, and bilevel high-speed EMUs don’t exist unless you count the 240 km/h bilevel Shinkansen that worked so poorly they were retired and replaced with single-levels. A 400-meter TGV Duplex actually has a few seats less than a 4-abreast 400-meter Shinkansen (1,020 vs. 1,098), but that’s not just the power cars but also the cafe and baggage space.
They still use the Shinkansen bi-levels to bring people to the ski stations!
1634 passengers with skis and snowboards in the 2 x 8 cars 402 m long bi-level Shinkansen.
Because they are fixed together, high-speed trains are strictly speaking trainsets rather than locomotive hauled, ie you can’t just uncouple them from the powercar. The TGVs, for instance, have power cars, but they aren’t really loco-hauled. Not that it really matters, but you’ll get railfans being silly at you.
Rail adhesion and therefore low-speed acceleration is better with distributed traction (ie MUs) than with a traction vehicle.
That’s less important to a high-speed service which doesn’t have frequent stops and which is mostly accelerating at speeds high enough that the adhesion isn’t the limiting factor.
But it doesn’t hurt to use distributed traction, and most high-speed trains do. Also, if they’re running on conventional lines, (often at one end of a route) then they have lower top speed and more stops, which is the point where distributed traction becomes a winner – that’s why the Germans, who have a lot of ICEs running on conventional track, use distributed traction and the French, whose TGVs run much more on the LGVs, have power cars.
Actually, that’s the differentiation I make. “loco-hauled” means non-distributed power, but one or two power cars per train. In the case of the ICE-1/2, the power car is essentially a modified locomotive (I think a modified BR 120). The TGVs also have power cars/locomotives, and, at least in the case of the TGV-SE, they could be easily switched; in fact, the spare “La Poste” power car has been used in regular TGV-SE sets, when one of their power cars was not available.
Distributed power was introduced (in Germany) with the ICE-T and ICE-TD train sets, followed by the ICE-3 sets (which are considered to be the precursors of the Siemens Velaro type).
I found a study with charts and graphs and the formulas used to generate them, which I can’t find now. I’m sure there are other studies that find the same thing. There is a trade off between top speed and acceleration. In typical suburban service where the train is stopping every few minutes you want aggressive acceleration and braking. The train that gets to it’s lower top speed very very quickly is able to maintain it for most of the trip to next very close station versus the train that spends half the time getting to a higher top speed and half the time slowing down, that train takes longer to get there. Not by much but over a few suburban stops it’s significant.
The wunder power electronics that give us AC motors on trains soften the impact a bit but trains still have gearing. For suburban service you want to trade high acceleration for top speed.
Fascinating. Please do post more.
Wow, this is crazy. So a top-of-line EMU can save over TWO WHOLE MINUTES serving a given station stop vs. a diesel loco-hauled train. In other words, an hour-long trip on Chicago’s Metra with fifteen stops could potentially go down to 40 minutes with the increased acceleration and shortened dwell times.
This is literally the kind of thing you expect a smart transit agency to be considering – how they can serve their passengers with better trains and faster trips – but so far Caltrain is the only one in the US to do so.
/* “This is the kind of thing you expect a smart transit agency to be considering – how they can serve their passengers with better trains and faster trips */
Philadelphia’s SEPTA is, of course, doing the opposite and buying a new fleet of locomotive-hauled bilevels….
Which I hope they will use intelligently on express-type service from areas like Paoli, Wilmington, Trenton, Doylestown. Not the ideal equipment, but price was right.
@ckrueger99: I checked into your question and yes, the good news is that they’re planning to put the bilevels on those more heavily-used routes.
That said, it should be uh, “interesting” to see how much of their efficiency is lost when hundreds of riders exit a packed bilevel train and have to pass through the subway-like turnstiles SEPTA’s installing as part of the Key farecard rollout. But that’s a topic for a different thread …
Train-to-platform egress capacity is a much bigger problem for bilevels than platform circulation.
Partly because there are more people on it.
SEPTA Regional Rail is so hopelessly far behind every other North American transit agency on accessibility that bi’s should be a real gas with all their short and narrow low platforms that can’t platform all cars on a train. Rush hour bi’s *might* make a modicum of sense for them if the heavily-used routes were any better off than the rest of the system at level boarding (or really any accessibility compliance whatsoever). But nope…only about 20% of their NEC platforms are level, and the only forward progress they’ve been making on the Keystone are the shared Amtrak stops that PennDOT has been funding over their heads for upgrade.
Since they’re so inept at managing a car order, it would also make a modicum of sense in a neutral-or-better accessibility universe for their procurement dept. to consider replacing the Silverliner IV’s with a copycat order of NJT MLV EMU’s after NJT has beaten the bugs out of them, simply as means of keeping both hands from their own necks on a repeat of the Silverliner V fiasco. But, alas, all that fourth-world platform accessibility…and the fact that instead of ordering “It Just Works™” third-generation Bombardier MLV coaches that could potentially safeguard the SL6 EMU procurement by being trainline-compatible with those new NJT EMU’s they instead let themselves get locked into CRRC’s low-bid foray into its first-ever attempt at FRA compliance with a brand new design that’ll only have 45 examples produced. They’ll never learn.
Then there was the mindboggling news that SEPTA might direct some bilevels on the *Norristown* line as part of the I-76 traffic mitigation project…
A key is in how they replace the Silverliner IVs.
I made a short slide presentation on the EMU vs. electric locomotive issue last year, but never published it on my blog. Here it is: http://tillier.net/stuff/caltrain/diesel_vs_elecloco_vs_emu.pdf
Upshot: compared to diesel, electric locomotives produce less than 1/3 the time savings of modern EMUs.
Oh, and look what just popped out of the paint shop in Switzerland:
The FLIRT 3 may be a little bit heavier because of the improved crashworthiness. That would explain the discrepancies. Or, it could also have to do with the seats etc. ordered by the customer.
The videos I saw were not of the FLIRT 3 – they’re the FLIRTs that Hungary and Switzerland have.
Could you link to Python3 instead? Python2.7 is presently deprecated and is EOL at the end of the year with no security updates.
Wait, what? Last year I was told I could use either and was convinced to use 2.7.
Yes, that was last year, which is why half of our supporting libraries at work *still* don’t support Python3.
/This will be a disaster, and the BDFL resigned over it before it could all go horribly wrong.