Gas-turbine HSR vs electric

the idea of carrying an auxiliary diesel engine for "maneuvering" , like a ship, is quite interesting.
It helps with the largest technical objections to a GT powerplant, but not the thermal ones.
Now a waste heat boiler for steam heating and an absorption chiller for cooling would help shift the analogy from aircraft to ships.

From what I read, the JetTrain's addition of a separate generator for head end power wasn't necessarily groundbreaking, but configuring it in a way that enabled it to work together with the turbine and be used in lieu of it for moving the train itself at low speeds, WAS.

It's kind of like the design philosophy behind the Prius. People who live and work in rural areas are usually disappointed by the Prius' fuel economy, because they spend most of their time driving it under conditions where internal combustion engines are efficient anyway. The people who see the HUGE fuel economy boost are people who spend 2/3 their time driving to work at 80mph on a freeway, then sit in gridlock for another 30 minutes to go the last 2 miles, because that's the use case where an internal combustion engine is horribly inefficient.

I wonder... if you were running a JetTrain through an area where 150mph operation was out of the question, but 30mph wasn't good enough (say, 79mph track through South Carolina), could you shut down the rear power head's turbine and run IT entirely from the rear HEP generator? In other words, have the rear power head contributing nothing to the front power head's pulling strength (which apparently, is sufficient for 106mph operation if there's no rear power head at all), but at least spin the rear power head's wheels fast enough to keep it from acting like an anchor with its own turbine shut down? Or, alternatively, can the motors in a power head unit be completely disengaged from the wheels so it can be passively towed while completely shut down? Or would you just divide the power generated by the front unit between both power heads, and have each one working to drive the train at some speed up to around 106mph?

I dont see why a two engine semi-permenantly coupled train set wouldnt have a common power bus, cabled from end to end, so that either generator would power all the traction motors.

Yeah, I guess that makes sense. AFAIK, most electrified trains have only a single pantograph, and JetTrain is basically an Acela that carries its own pair of diesel generators, so I guess it's obvious that there would be a high-voltage power bus connecting the two.

The Jettrain only carries one gas turbine and it powers everything, inluding HEP, there is no other source of power.
The Jetrain is In pueblo stored as another failure of fossil fuel powered HSR.
No trains in US have a powerbus other than HEP. only exception being the married pairs of permanently coupled MU's at LIRR, NJT, MNCR and maybe SEPTA.

>The Jettrain only carries one gas turbine and it powers everything, inluding HEP, there is no other source of power.

The prototype JetTrain had only one gas turbine, because only one prototype power head was built. A revenue train with Acela-design railcars would have (and require) two, one at each end.

I don't know whether their prototype had the second engine for HEP, and I'm still trying to find an official reference for it, but according to Wikipedia, it most certainly was intended to have a second engine for HEP that could be used for locomotive power as well: http://en.wikipedia.org/wiki/JetTrain#JetTrain

I think it's a bit premature to call it a 'failure'. The cancellation of Florida's JetTrain order had nothing to do with public rejection of fossil fuels for high speed rail, and everything to do with the fact that the program that would have built the tracks the trains would have run upon was itself canceled. Bombardier doesn't go out of their way to advertise JetTrain, but if you check the time/date stamps on everything JetTrain-related on their web site (found via Google), they ARE actively maintaining it.

Bombardier knows that they don't HAVE to market it. If a state wants it, they'll contact Bombardier, and I have no doubt that Bombardier would be absolutely delighted to sell them several dozen Acela-type trainsets with JetTrain-derived power heads, with or without pantographs for tri-power capabilities.

Fuel economy arguments aside, I can think of one very good reason for Florida to keep enough JetTrain-type power heads around "forever", even if the rail network ends up 100% electrified someday and the majority of trainsets run from Acela-derived catenary-only power heads: hurricanes. They'd cost a tiny bit more to run than their all-electric brothers due to the added weight, but they'd be a cheap insurance policy against having a large part of Florida's HSR network shut down for a week or more after a major hurricane due to catenary damage. In fact, I think that was one of the original arguments behind the decision to go with JetTrain.

i really think your flogging a dead horse . nobody anywhere in the world has done any work on gas turbine locomotives in the last , what 20 years ??? , i cant even see what advantage they offer over a high speed diesel engine . presuming cantenary is out of the question , otherwise electric is a hands down winner for hsr . the only possible use for gas turbines would be in gensets , ( where multiple turbines are used running at peak efficency , and shut down one by one when not needed ), but again a truck or high speed marine diesel could do that as well .

Well, 2004 was officially when Florida decided to go with JetTrain (before the HSR program itself got canceled). That was only ~6 years ago

Is there really, truly, a high-speed diesel-electric engine that can flank an Acela-type trainset and run it at 150mph, though? And be outfitted with pantograph for dual/tri-power capability so it can run from overhead wires when they're available, but run from diesel when they're not? Remember, a big part of Acela/JetTrain's appeal is flexibility. It doesn't force you to do 100% of anything. You can have a rail network that objectively is a total mess of standards and running conditions, and make it immediately-usable anyway.

miamicanes wrote:Well, 2004 was officially when Florida decided to go with JetTrain (before the HSR program itself got canceled). That was only ~6 years ago

Is there really, truly, a high-speed diesel-electric engine that can flank an Acela-type trainset and run it at 150mph, though? And be outfitted with pantograph for dual/tri-power capability so it can run from overhead wires when they're available, but run from diesel when they're not? Remember, a big part of Acela/JetTrain's appeal is flexibility. It doesn't force you to do 100% of anything. You can have a rail network that objectively is a total mess of standards and running conditions, and make it immediately-usable anyway.

Maybe a better question would be is there a less-customized trainset design available that can do tilting while retaining as much standard car and loco parts as possible. Are there cars that are more or less standard-body with tilt purely in the trucks instead of a ground-up design? Or at least something that can achieve 150 MPH with as little customization from a regular car as possible? It could significantly lower costs if Amtrak could pool its next-gen car orders around a modular design with minimized differences and as much maintenance commonality as possible. That would allow them to buy a lot more for the NEC without going through the ordeal of a totally custom Acela order that's completely alien to all Regionals equipment. I mean, it's not like there's a humongous speed difference between the 100-125 MPH standard trainsets that operate on parts of the NEC (I believe MARC commuter rail is rated for 125) vs. 150 quasi-HSR. I'm less informed about loco specs and whether Acela locos tilt as well. If not would it also be possible for future electric orders to achieve similar commonality between regular electrics and quasi-HSR electrics so there can also be a pooled loco order with minimized differences between Regional-rated and HSR-rated speeds? What else would go into the design beyond a higher-speed engine? Because they could run a lot more infill service if things were modular enough for a regular electric to get coupled on-the-fly with a shorter-consist 150-rated trainset and make at least a consistent 125 on full-speed stretches and no more than a 10-15 MPH penalty over the Acelas on curvy sections. That's very acceptable flexibility for increasing service levels while the smaller fleet of HSR-rated locos slowly increases. And could help them upgrade some Regionals into a sort of mid-tier service while de-clogging the line of some of the slowest trains.

This would also put a dent in the problem of how do you do NEC-like speeds on non-electrified lines. If you can couple some tilt trainsets to a zippy diesel with somewhat shorter consists than a full-on 150 electric and still do 125 on properly rated track that expands the branchline possibilities exponentially. And fill an intermediate step so the daunting cost of electrification doesn't have to get tackled in one monolithic capital investment. Not to mention using existing diesel fueling and maint facilities without having to require a nonstarter novelty like JetTrain technology. I could see that really making a huge ridership impact on the Springfield Line if closer-to-HSR trainsets could traverse it. Ditto eventual upgrades to the B&A so the whole current inland route is more competitive with shoreline Regionals on time to Boston.


I dunno...train experts: how close can we get on modularity? Anything significantly closer I've got to think is a better deal than buying and maintaining more oddball Acela sets, especially with their limited lifespans.

Well, unfortunately, you pretty much summed up the reason for USDOT's investment in JetTrain -- to create a reference design that COULD become the de-facto "off the shelf" high-speed passenger rail solution for most of the US. Remember, "JetTrain" isn't really a trainset -- it's literally an Acela power head that had the generator added to what was presumably empty space before. From what I understand, Bombardier built the Acela's power head from the shell design of a TGV, but had to leave lots of empty space inside because in Europe, first-class passengers ride in the head car behind the engineer. In America, that's not allowed, so they just left it as empty crumple zone to keep the FRA happy. To make JetTrain, they just put the space to better use and put the turbine, generator, and fuel there instead.

Like it or not, right now, JetTrain is the closest thing America has to "off-the-shelf" 150mph HSR that can run without electrification. Talgo is the closest alternative, but it's only FRA Tier-1 and can't run above 125mph. I think Siemens has at least one 200km/h design that's theoretically FRA-approvable, as well as the right to build JetTrain implementations of its own.

JetTrain's reference design also has one huge competitive advantage over everything else -- it uses Acela trainsets, and Acela's R&D costs were already paid for by Amtrak. Ultimately, the only problem they weren't able to fix was the width of its tilt zone... but if you're building brand new HSR tracks anyway, it's probably cheaper to just buy an extra 10" of corridor than to pay the R&D costs of redesigning the entire trainset to make it narrower.

>>> because in Europe, first-class passengers ride in the head car behind the engineer.<<<<

I don't know where you got that information but on TGV the Power heads do NOT carry passengers. on some of later ICE's yes but not the TGV or Eurostar.

An interesting JetTrain video I just found.

http://www.youtube.com/watch?v=mueMepjBgyw

Where would you want to go 150 mph thats not electrified , or could be electrified , anyway ?

Champlain Division wrote:An interesting JetTrain video I just found.

http://www.youtube.com/watch?v=mueMepjBgyw

This guzzler of oil products is entirely inappropriate to modern conditions.

This guzzler of oil products is entirely inappropriate to modern conditions.

Not that this is going to convince anyone, because JetTrain opponents won't consider any testing data published by TTC and Bombardier. They have already made up their minds due to their pro-catenary agenda and are determined to down it with disinformation. Most are against JetTrain because it is "non-green" in that it directly burns fossil fuel thereby emitting particulates while they perceive electric trains as "green" because they don't......directly. It's a microcosym political debate similar to the conservative versus liberal battle over Amtrak's direct subsidy versus Aiports and Airways' indirect subsidy via trust fund. (I doubt you would be able to convince the typical taxpayer's wallet or pocketbook that there is any difference.)

If you consider JetTrain a guzzler of diesel fuel then you must also consider a typical Amtrak P-42 doing 110 mph on the NEC between D.C. and Philly or between Hudson and Albany, NY on the Empire Corridor (behind both of which I have ridden) in the same light. You should be as down on Amtrak's diesels as you are on JetTrain because testing at TTC proved that it burned up no more fuel than a P-42 would on the same route plus it can go 40 mph faster and out-accelerate it. No previous diesel turbine system can claim a fuel efficiency record like that.

JetTrain didn't fail because of its technology; it failed becaused at least 50% of the people in the United States are, and always have been, politically dis-inclined to paying for the infrastructure that would have made it a success.