Lets suppose that the promoters of the Texas 'high speed' rail link between Dallas and Houston scare up enough investors to make the project possible. Lets further suppose that they decided that they must run along existing track, with perhaps some straightening of the right-of-way and, furthermore, they cannot afford to electrify the line.
What is the top speed that they could hope for on first class track and roadbed, with a power car on both ends of the train, so that it would not have to be turned at the end points, pulling six cars? Keeping in mind that I am not an engineer, would it be diesel or gas turbine or could it be either?
I would think that 125 MPH would be possible. The Pioneer Zephyr exceeded 110 MPH with 600HP, though all it had was the locomotive and 2 cars. Main issue is that the axle mounted traction motors used on American locomotives would be hell on the track at 125 MPH.
- Erik
The E units on one carrier I am familiar with were delivered with 120 MPH gearing in the 1940's. I was in the cab of one and observed 118 being indicated. What modern power can be designed for is in the hand of the engineers.
Never too old to have a happy childhood!
The CB&Q 'E' unit fleet was geared for 117 mph(E5 & early E7 order), Following E7, E8 & E9's were geared for 98 mph. I rode in the cab of these units several times. At speed, they were very smooth riding, I suspect good track, no freight slack action, and even acceleration reduces the 'pounding' from nose suspended traction motors. Keeping the HP to trailing tonnage high will reduce this issue. If your proposal is going to use exsisting trackage, or even new trackage laid next to an existing freight line - the grade crossings and curves are going to limit your speed. I sort of doubt an average speed of 125 mph. The engines should be able to peak out at 125 mph on short sprints if there is enough tangent trackage.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Amtrak diesels do 110 mph in Mich and (if not now, soon) in Illinois.
They have diesel-electric MU train sets in England that have no trouble at all with 125 mph.
I believe there is a spec out there for a 125 mph North American diesel locomotive. There was blurb on Progress Rail's web site. It would have frame mounted traction motors.
http://www.progressrail.com/transit-locomotives-passenger.asp
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
What about a Gas Turbine trainset like the RTL turboliners or CN Turbo train you could achieve speed similar to a all electric
Railroad to Freedom
I am an advocate of a cogent "engineering approximation", but you may want to sharpen your pencil on that claim. Aerodynamic resistance is the dominant force at those speeds, and that force increases with the square of speed. Hoerner (1965, Fluid-Dynamic Drag, Hoerner, Brick Town, New Jersey) infers from drag data that there can be a cubic term relating to the swaying of the train cars but finds that effect only in freight trains.
Hoerner's book is filled with practical applications regarding experiment and theory of drag for all modes of transportation -- trains, planes, cars, boats. It was recommended to me by a mechanical engineering professor at Northwestern University, and I purchased it in the mid 1970's by sending a check to Dr. Hoerner's widow, who was filling orders. So if you want a copy, it may be as challenging to acquire as Waredale's "Red Devil and Other Tales of the Age of Steam."
So, a 20 percent increase in speed (from 125 to 150 MPH) increases the fuel consumption on a per-mile basis by the increase in drag force ("work" is force times distance) or 1.2-squared minus 1 or 44 percent. That increase in speed increases the HP requirement, which is the same as the fuel consumption per unit time by 73 percent. The fuel consumption per unit time is up 73 percent, but you are going 20 percent faster, so the net fuel consumption per mile is up only the 44 percent, which is a ways away from doubling.
If you are comparing 125 MPH to about 80 MPH (the 79 MPH speed limit for non-automatic train step territory), the gallons per mile increases by a factor 2.44 (144 percent increase, where a 100 percent increase is a factor of 2 or double).
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
The RTLIII Turboliners did 149 mph during acceptance testing. Key to high speed, other than horsepower is P2 forces which are directly related to unsprung weight. Diesel electrics with axel mounted motors tear up the right of way at speeds above 90 mph. The Turboliners with cardan shaft drive had very low P2 Forces. I co-aurhored a paaper on this amny yeas ago.
German ICE-TD DMU regularly touch 200kph (140 mph) between Hamburg and Luebeck on their way to Copenhagen.Those that start at Berlin Hbf would also hit 200 kph between Spandau and Hamburg, There is of course no reason why a diesel locomotive can't use Quill Drive.
I think 200kph is the equivalent of 125mph (or near enough) rather than 140mph.
As mentioned earlier the Inter City 125s in the UK do what's said on the tin, and have been doing so for over 35 years. Originally built with Paxman Valenta engines, now with more modern replacements. I haven't got reference books to hand, but formation is two powers cars at c2,250 hp each with 7 or 8 coaches in between. Engines are less than 80 tones, coaches about 35 tonnes. They have not got a reputation for damaging the track.
Max speed on test was I think 143mph.
Jerry Pier Key to high speed, other than horsepower is P2 forces which are directly related to unsprung weight. Diesel electrics with axel mounted motors tear up the right of way at speeds above 90 mph. The Turboliners with cardan shaft drive had very low P2 Forces.
Key to high speed, other than horsepower is P2 forces which are directly related to unsprung weight. Diesel electrics with axel mounted motors tear up the right of way at speeds above 90 mph. The Turboliners with cardan shaft drive had very low P2 Forces.
The P2 forces would also be proportional to the square of the speed, with the forces at 125 MPH almost twice that at 90 MPH for the same unsprung weight.
One potential way of reducing unsprung weight is to use higher rotational speed AC motors, which should reduce the size an weight of the motor. A smaller motor would then allow the center of mass to be placed closed to the "nose" further reducing effective unsprung weight, This may be adequate for 125 MPH, any faster then either a Cardan or quill drive would be necessary.
P.S. Jerry, i had you in mind in my earlier comments about 125 MPH being impractical for American axle mounted traction motors.
erikem Jerry Pier Key to high speed, other than horsepower is P2 forces which are directly related to unsprung weight. Diesel electrics with axel mounted motors tear up the right of way at speeds above 90 mph. The Turboliners with cardan shaft drive had very low P2 Forces. The P2 forces would also be proportional to the square of the speed, with the forces at 125 MPH almost twice that at 90 MPH for the same unsprung weight. One potential way of reducing unsprung weight is to use higher rotational speed AC motors, which should reduce the size an weight of the motor. A smaller motor would then allow the center of mass to be placed closed to the "nose" further reducing effective unsprung weight, This may be adequate for 125 MPH, any faster then either a Cardan or quill drive would be necessary. - Erik
Can't believe I screwed up the speed conversion, thanks Eric.
There is a nice brochure on the Alstom website featuring the new AGV (produced as the Italo for NTV in Italy) page 11 of the brochure shows a power truck with frame mounted Permanent Magnet synchronous AC traction motors and a man with his hand on one of the motors. Power density is greater than 1kW/kg.
Alstom AGV brochure
beaulieu Can't believe I screwed up the speed conversion, thanks Eric.
You're welcome.
It would be nice to see 110-125 MPH speeds on the LOSSAN corridor, though 125 MPH would only be practical on the stretch through Pendelton. More time would be saved in reducing the number of miles where the trains are limited to 25-35MPH due to curvature and double tracking the line. One reason for the new interest in LOSSAN speeds is starting to commute between Solana Beach and Irvine.
The permag motors on the AGV are intriguing, and what I was thinking was pretty close to the motor mounting on the AGV. Especially intriguing was the 3.6kV bus on the inverter just about perfect for a recreation of the DL&W or Milw 3kV electrifications.
the milw. electrification started out at 3 \kv, but then they shimmed the motor-grnerator fields and operated at 3.3kv - except in Butte where they shared some \BA&P trackage at 2.4 kv, into the station, and the Tacoma roundhouse where they were run on and off the turntable using a 440 v jumper!.
CNW 511 at 90mph by Jim53171, on Flickr
I was actually doing 103 (38 seconds per mile).
Even at this speed, the locomotive was still generating over 500 amps!
Built and marketed by Canadian Bombardier Transportation, JetTrain is a recent
advancement in conventional steel-wheel-on-steel-rail technology. The product is the result
of more than 15 years of development and is based on the Acela Express trainset
technology now being used in Amtrak’s Northeast Corridor. The typical trainset involves
one or two locomotives and a set of passenger cars running on non-electrified, standardgauge
railroad track. Powered by a Pratt & Whitney turbine engine, the JetTrain locomotive
is capable of sustained operating speeds of 240 km/h (150 mph) and is 20-percent lighter
than a conventional diesel locomotive.
Dave
Lackawanna Route of the Phoebe Snow
What is the "recent advancement" over former turbos?
Replying to the gas turbine question, the problem is fuel efficiency at other than full load or full speed.
The question was not about fuel efficiency, it was about speed without electrification. The Bombardier Train is capable of 150 mph.
Obviously the cost of speed was too high. They took it on tour around the USA. They couldn't sell it. It now lives in a museum. It looks just like the Acela.
Phoebe Vet The question was not about fuel efficiency, it was about speed without electrification. The Bombardier Train is capable of 150 mph. Obviously the cost of speed was too high. They took it on tour around the USA. They couldn't sell it. It now lives in a museum. It looks just like the Acela.
It looks like an Acela locomotive because it pretty much was one. They took out the main transformer and plopped in a gas turbine - generator set. I believe the gas turbine was a helicopter gas turbine derivative. So, it was mostly off the shelf stuff pieced together.
The development was funded in part by the FRA as part of the high speed rail program. I'd say it was more a "proof of concept" design than a final product as there is currently no non-electrified corridor that needs more than a 110 mph locomotive design.
It does make for some interesting thoughts about how high speed corridors could be build out and improved in stages rather than in one fell-swoop.
As much as we would like to do away with expensive electrical lines and maintenance that comes with them , they are a benefit. If you wanted to achieve speeds higher than 120mph you would need a special design train with special parts and engineering required to design special versus electric high speed trains which have a variety of manufacturers all over the world. Besides the goal is 205mph regular service is the goal here not 120-150mph Oil is also several times more expensive than then electricity, one of the reasons why I might add that rail transit is increasing in popularity. Sure electricity isn't inherently cheap but it free you from the rollercoaster that is the fuel market just ask freight rail what they think of oil prices. Not too happy about it. The gap further grows if electricity can be partially made in house through say solar panels which advancements will make them much cheaper in the future. Another advantage is regenerative breaking which allows energy to be sent back to the electrical grid. The advantages of electrification are just far too great not to use, atleast for the purpose of high speed trains. With high speed rail you might as well "go all the way" because HSR projects have high engineering requirements and cutting corners isn't wise. Just my .02
Although there isn't a definite figure denoting speed limit for diesel locomotives , clearly the higher speeds the more they get behind electrics because of their much lower specific power output per mass unit ( modern electrics turn out about four times the power per unit of engine mass as diesels ) .
Higher speeds not only ask for higher tractive effort to overcome increasing running and air resistances (!! thus vastly increased power output since it's the product of speed by effort !!) but in order to commercially use these high speeds to any advantage acceleration must also be more energetic to contain time and road needed to reach scheduled speed . This is why performances like those of modern electric multi-unit trains are simply beyond reach with diesel traction .
Off hands I'd figure practical passenger train speed range with diesel traction to extend to some 100 - 110 mph , with a very slow possible approach of 120 mph on long through-runs , the latter describing pretty much an economic as well as technical limit for thermal energy locomotives , generating traction power on board as in contrast to electrics drawing it continuously from wire .
Regards
Juniatha
Juniatha Off hands I'd figure practical passenger train speed range with diesel traction to extend to some 100 - 110 mph , with a very slow possible approach of 120 mph on long through-runs , the latter describing pretty much an economic as well as technical limit for thermal energy locomotives , generating traction power on board as in contrast to electrics drawing it continuously from wire . Regards Juniatha
Um, what about the British Rail HST, also known as the Intercity 125. A pair of lightweight Diesel power cars (about 2000 HP each) at the ends of a rake (as the British call a consist) of lightweight Mark-III coaches. I am thinking that train achieved 125 MPH in regular service quite handily.
IMHO it is not the top speed that is most important.
1. On present tracks with their many slow sections it is acceleration that is most important.
2. As pointed out above the power output of an electric is about 4 times as much as a diesel for loco mass. So the more the speed restrictions and grades the more power required.
3. The Joilet - East ST. Louis line is essentially flat and not many sharp curves.
4. If the route from Dallas - Houston meets these same criteria then a diesel can be allowed.
5. The biggest problem is grade crossings and the present FRA limit of 110 MPH for a 4 quadrant improvced crossing and 90 MPH for other grade protected crossings.
6. Otherwise the expense of grade separations for higher speeds than the above 90 & 110 are required.
Paul Milenkovic Juniatha Off hands I'd figure practical passenger train speed range with diesel traction to extend to some 100 - 110 mph , with a very slow possible approach of 120 mph on long through-runs , the latter describing pretty much an economic as well as technical limit for thermal energy locomotives , generating traction power on board as in contrast to electrics drawing it continuously from wire . Regards Juniatha Um, what about the British Rail HST, also known as the Intercity 125. A pair of lightweight Diesel power cars (about 2000 HP each) at the ends of a rake (as the British call a consist) of lightweight Mark-III coaches. I am thinking that train achieved 125 MPH in regular service quite handily.
...or these: http://en.wikipedia.org/wiki/British_Rail_Class_221
125 mph diesel electric MU cars, with tilt.
Paul -
well , if you consider it handily ...
(deleted by = J = )
Add :
That’s what I call a swift get-away:
Taurus 1216 series Bo-Bo electric 0 – 220 km/h in 40 seconds ; 0 - 230 km/h in ~ 45 seconds
http://www.youtube.com/watch?v=PjZB30iXVio
http://www.youtube.com/watch?v=1XpOTczFTxo
Juniatha Off hands I'd figure practical passenger train speed range with diesel traction to extend to some 100 - 110 mph , with a very slow possible approach of 120 mph on long through-runs , the latter describing pretty much an economic as well as technical limit for thermal energy locomotives , generating traction power on board as in contrast to electrics drawing it continuously from wire .
UP's M-10001, the original City of Portland, hit 120 MPH on a five mile stretch of track in Nebraska on the 56 hour LA-NY run in 1934. At that time, the train was powered by a 12 cyl, 900HP Winton 201A engine, consist was the engine followed by 6 cars. Needless to say, it did have an ample chance to build up speed and it was lighter and had a much lower drag coefficient than current Amtrak designs.
A diesel electric locomotive equipped with a ~5 ton Lithium battery should have acceleration close to that of an electric locomotive, but the battery would have to be changed out monthly with existing battery technology. A hybrid gas turbine/battery locomotive might make more sense, the lighter weight of the prime mover would allow for a larger battery (chief advantage being cycle life) and the battery would allow the gas turbine to run much closer to constant output than possible without a battery. In both cases, the battery would allow for recovery of braking energy.
Juniatha Add : That’s what I call a swift get-away: Taurus 1216 series Bo-Bo electric 0 – 220 km/h in 40 seconds ; 0 - 230 km/h in ~ 45 seconds http://www.youtube.com/watch?v=PjZB30iXVio http://www.youtube.com/watch?v=1XpOTczFTxo
Strange German dialect they were speaking in the cab . . . sounded like Polish!
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