Number Crunching Amtrak Energy Use

[HarveyK400]

My limited recent experience with Amtrak is that the trains, both long-distance and Midwest Corridor, have been pretty full and need to be given a break regarding energy consumption that is related to train weight.

• The Builder and Southwest were nearly full across Montana and Colorado in late September and mid-May respectively. 
• The 7:00am from Chicago to Saint Louis and Springfield may have been half full; but the returning trains were on average three-quarters full in the middle of the week with three coaches and a buffet-business class car.

The Chicago - Saint Louis trains are turned; but the Hiawathas have the "cabbage" car ballasted to 263,000 lbs without the engine.  This adds the equivalent of two more coaches in train resistance and consumes more fuel.

A 10-car, 2-locomotive superliner train with 300 passengers works out to roughly 7,700 lbs per passenger, about three times the weight of a compact auto.  Then too, it's travelling with the motel and restaurant while an auto, bus, and plane travel between fixed facilities.  I am not advocating meal stops or over-nighting.  On-board facilities make up for running slower on a 19th Century alignment than flying and, in many cases, driving on 20th Century expressways. 

If the "average" corridor train averages 20 passengers per car, the weight for a 4-car train works out to around 10,000 lbs per passenger!  This is four times the weight of a compact.  Rush hour Hiawatha #330 with 270 passengers and "cabbage" car weighs 4,100 lbs per passenger.  Another coach was added and the train still may be full.  If Amtrak achieves forty-six passenger-miles per gal, a full train such as the Hiawatha would achieve over 150 pm/gal and beat a Prius three times over. 

I still think pricing is the key; and Amtrak is focused on revenue per passenger more than train revenue.  Could the average ridership double if train tickets were half the price?  Policymakers should consider achieving over 90 pm/gal and taking as many cars as possible off congested roads.

For Metra, a more typical 8-car rush hour train with 1,050 passengers works out to just 1,400 lbs per passenger, almost half the weight of an auto.  There is no direct relationship between weight, so a rush hour Metra should be quite a bit better, but not four times more fuel efficient than the average Amtrak.  A 6-car mid-day train dead-heading cars with only 300 passengers comes to 6,400 lbs per passenger.  In all fairness, the extra cars often represent equipment repositioning for a heavier load in the opposite direction and the contingency for unexpected passengers. 

 

[Autobus Prime]

People who claim that buses are the transportation be-all end-all forget that buses were largely responsible for driving people away from mass transit.

Do you have anything to justify that opinion? My opinion is that automobiles were the largest factor to cause people to abandon mass transit.

gd:

I suppose so. It was late and maybe I should have used more sand toward the end there...slipped a little. It's kind of hard to say the car did it, though, because at the same time the country was being rebuilt in a way that made the car necessary, and one part of that was the bustitution of transit systems. But that's another ugly mess for another day.

Anecdotally, you and I know that people don't like city buses. I ride city buses, and I have to say I see their point. Noisy and shaky, for one thing. If the bus line was treated as a show horse, not a pariah...but again, that's for another day.

My major point still stands. As utilized now, /according to the figures given by PM/, Amtrak gives tiny-hybrid-car level fuel economy, but with comfortable seating, bedrooms and a restaurant on board, the capability to safely go upwards of 80mph, and a traffic management system that keeps traffic jams uncommon, not a daily reality. And potentially, with very few changes and no sacrifice in comfort, we could improve the efficiency, go 100mph, maybe 120, and use that system to keep the trains moving on time.

[gardendance]

People who claim that buses are the transportation be-all end-all forget that buses were largely responsible for driving people away from mass transit.

Do you have anything to justify that opinion? My opinion is that automobiles were the largest factor to cause people to abandon mass transit.

[Autobus Prime]

PM:

Here we go again. I think my favorite argument of yours has been "that SUV with 3 of your buddies riding is more efficient than Amtrak". Of course it's convenient to forget that 90% of the time that SUV has one occupant commuting to work. Once you buy the car, you use it all the time, not just when it can be used at max efficiency. You have to. Cars cost a lot to keep. It's also easy to forget that those four guys in the SUV after the ball game were probably at creep speed for several hours in the obligatory traffic jam. So much for efficiency.

I see some of that here, too. You've calculated an overall "fuel mileage per car" for Amtrak based on their reported energy use. Well and good. But then you compare that unfavorably to the 6 mpg a bus gets. Full service brakes! You're not using an overall energy consumption value, but a value that disregards time spent in heavy traffic, time spent idling and going nowhere, and other periods when the bus can't get highway mileage. Your Amtrak calculations include all of these! How is that comparison at all valid? Also - time stopped at signals waiting for freights. And I would love to see how that varies from RR to RR!

Listen, engineer. (and it's ok for me to say it, I'm one too) We like to forget it, but you can't just look at the vehicle. You have to look at the system. My car can get 30 mpg easily, but in practice I get around 18 mpg. Lots of time stopped at lights, going in slow traffic, etc. And I don't even live in a very large city.

I forget what the average number of people per car is...around 1.2, I think, but that's probably high. Using a real-world fuel mileage of about 24 mpg for a practical-sized car like a Taurus or Accord, that gives you around 29 pax-mile per gallon, assuming you aren't stuck on the Jersey Turnpike, in which case all bets are off. The real-world Amtrak car you mentioned, assuming your figures are good, gets 52 pax-mile per gallon.

Could you beat this with a Prius? Barely. And for it to mean anything, everybody would have to get one. And everybody won't, because they are too small to be really practical. A car may be only driven by 1 person most of the time, but you can't buy it based on that, because in order for a car to be worth owning, it has to be usable for vacations with lots of luggage, hauling groceries and stuff around, moving extra passengers. There's a good reason the Accord is so popular.

Could you beat Amtrak with carpooling? Sure, but you won't. Because the main draw for a car is that it is convenient. It's right there. Carpooling takes that away. So to improve the car's efficiency, you have to make it less convenient. No sale. To improve the train's efficiency, the easiest way is to increase ridership. And one way to do that is to make the train more convenient - easier to get to, quicker, etc. So which one, do you think, would be easier to improve, if we bring the reality of human nature into the calculations?

One last point - have you ever ridden a bus cross-country? I have. NOT PLEASANT. It's tolerable for trips of 6 hours or so, if you don't have anything better, but I'm a lot easier to please than most. (Somewhat of a bus fan. :) ) The same thing goes, unfortunately, for most city buses. People who claim that buses are the transportation be-all end-all forget that buses were largely responsible for driving people away from mass transit. They don't *have* to be bad but it's really easy for them to be.


Summary: You are leaving out comfort and convenience, the very reason cars are popular. You are also comparing "Amtrak in practice" to "buses in theory" (and at other times "cars in theory"). Got to agree with the apples-oranges sentiment.

[erikem]

There is a widely-held assumption that not only are trains more fuel efficient than other modes but that trains are more fuel efficient by orders of magnitude.  Unfortunately, this has not been the case -- see David Lawyer's statistics and explanations at http://www.lafn.org/~dave/.

... 

Trains in theory could offer substantial savings in energy, but that would require changes in operating practices and perhaps some changes in expectations on the part of the advocacy community.  I offered some examples of how lighweight, streamlined equipment, none of it exotic by current standards, could double Amtrak fuel efficiency.

I looked at Lawyer's website and while I would quibble about the relative efficiencies of cars and locomotives, he does get it right in that LD trains weigh A LOT per passenger. Interestingly, that is something that John White brought up in the mid-1970's in his book The American Railroad Passenger Car. I'd also argue that an electrified line offers the advantage of a much more diversified energy supply, but the only LD electric line is the Northeast Corridor.

Kind of a shame when remembering that both the M-1000 and the Pioneer Zephyr could hit  110 MPH with a 600HP engine and the M-1000 was originally designed to use engine heat for heating the train.

Commuter rail is a different story in that the GO Transit design weighs less than a 1,000 pounds per seat. A further improvement could be made by using hybrid locomotives to store braking energy, though batteries don't yet have the cycle life and ultracaps don't have the specific energy needed to make a practical hybrid commuter locomotive.

[Anonymous]

Starting with http://cta.ornl.gov/data/tedb26/Spreadsheets/Table9_10.xls, Amtrak's most recently-reported energy use is 2700 BTU/passenger mile, down from a high of 3200 in 2000 and up from a low of 2400 in 1991.  Using a figure of 125,000 BTU in a gallon of gasoline (the high heating value) and 140,000 BTU in a gallon of #2 Diesel, this works out to 46 passenger-miles/gallon gasoline (MPG will be gasoline unless indicated).  Their averages work out to 20 persons per train car.  A train car averages 2.6 Diesel MPG, contrasted with a figure of 6 Diesel MPG stated for intercity buses.

Dear Paul, 

I am getting the impression that you are comparing apples to oranges here.  How exactly did you arive at the 6 MPG figure for intercity busses?  Since you cite no details on this figure the rest of the information in your post is useless. 

A better way to compare the fuel efficieny of busses to trains would be to compare the MPG per passenger seat rather than the average number of passengers carried.  By this method you can compare the potential energy savings of one mode over the other on equal footing.

However I must also note that there is more to energy efficiency than just MPG.  To be fair you must also compare the energy consumption of the infrastructure that supports the two modes of transport.  Wich consumes more energy to build and maintain, a mile of interstate freeway or a mile of 79 MPH mainline track?  You simply leave this part out of your equations.

When you come up with appropriate facts and figures Paul you will see that trains are the most energy efficient means of land transportation.

Scott

The amount of energy used in building a highway or railway line, when depreciation or the life of the project is considered, is probably marginal compared to the energy used in operations.

Highways and railway lines, together with their support facilities, are capital projects.  The cost of building them, at least in the case of a private railway line or one owned by a quasi governmental agency (Amtrak) is capitalized and depreciated over the estimated life of the asset.  The depreciation period runs for decades. 

The major costs associated with a capital project are labor, equipment, materials and overheads.  Most of these projects are built by contractors.  If the contract is a time and materials arrangement, the contractor bills out the equipment at so many dollars an hour.  Included in his equipment billing rate is the cost of the fuel.  If it is a lump sum contract, the contractor builds the cost of fuel into his estimate of the total cost of the contract. 

The cost of the fuel is capitalized along with the other costs associated with the project and is an element in the annual depreciation schedule.  

I have never worked for a government agency.  I am not sure whether the cost of highways is capitalized or expensed.  If it is not capitalized, then the cost of the fuel used to construct the highway would be a one off, which means it would have a big impact during the construction period, but it would have no impact over the remaining life of the project.  At the end of the project's life the outcome would be the same.

Although the cost of the energy used in construction may be capitalized, it is fair to say that the pollution is not embedded in the project.  So one might argue that it is a one off, which means there is a big blip in air pollution while the project is being constructed, offset by no construction pollution once the project is completed.  

[Paul Milenkovic]

Data on bus MPG is available from Bureau of Transportation Statistics at http://www.bts.gov/publications/national_transportation_statistics/excel/table_04_15.xls

That is an interesting point that the energy-intensity of the guideway/roadway should be taken into account in comparing the energy intensity of transportation modes.  I don't have any data on that but would welcome any input or comparisons on this issue.  One should also add the energy required to manufacture the rolling stock -- cars, buses, trains.  On the other hand, when the energy use of different modes of transportation is discussed in many forums, the fuel consumed by the vehicle is what is often reported.

As to the "apples and oranges" and the matter of a "fair" comparison between buses and trains, a large part of the improved fuel efficiency of buses is that they operate at higher seating densities, with the seats practically crammed together, and they operate at higher load factors, more people packed into those seats.  On the load factor issue, bus operators will dispatch more buses during peak travel times; Amtrak, however, is running fixed consists on its corridor trains. 

There is also an expectation in the advocacy community that trains provide a greater level of comfort through much lower seating densities along with amenities provided by non-revenue cars on long-distance trains.  The lower seating densities, the low overall load factors required so as to not turn people away at peak times, and the expected levels of amenities on trains are a tradeoff against fuel efficiency.  If the reason for promoting train travel is to save energy, for reasons of reducing oil imports, greenhouse gas emissions, and so forth, the advocacy community may have to accept reduced levels of such amenities on trains.

There is a widely-held assumption that not only are trains more fuel efficient than other modes but that trains are more fuel efficient by orders of magnitude.  Unfortunately, this has not been the case -- see David Lawyer's statistics and explanations at http://www.lafn.org/~dave/.

Amtrak as it is currently operated is not making a meaningful contribution to reducing energy consumption, owing to the current low level of patronage and current equipment and operating practices.  People keep saying "with the outrageous price of gas, Amtrak ridership is increasing and people will switch to trains."  Given the slim energy advantage offered by Amtrak, that more people are riding Amtrak reflects that the Amtrak fares are subsidized to the extent that they don't reflect Amtrak's energy costs.

Trains in theory could offer substantial savings in energy, but that would require changes in operating practices and perhaps some changes in expectations on the part of the advocacy community.  I offered some examples of how lighweight, streamlined equipment, none of it exotic by current standards, could double Amtrak fuel efficiency.

[SRen]

Starting with http://cta.ornl.gov/data/tedb26/Spreadsheets/Table9_10.xls, Amtrak's most recently-reported energy use is 2700 BTU/passenger mile, down from a high of 3200 in 2000 and up from a low of 2400 in 1991.  Using a figure of 125,000 BTU in a gallon of gasoline (the high heating value) and 140,000 BTU in a gallon of #2 Diesel, this works out to 46 passenger-miles/gallon gasoline (MPG will be gasoline unless indicated).  Their averages work out to 20 persons per train car.  A train car averages 2.6 Diesel MPG, contrasted with a figure of 6 Diesel MPG stated for intercity buses.

 

Dear Paul, 

I am getting the impression that you are comparing apples to oranges here.  How exactly did you arive at the 6 MPG figure for intercity busses?  Since you cite no details on this figure the rest of the information in your post is useless. 

A better way to compare the fuel efficieny of busses to trains would be to compare the MPG per passenger seat rather than the average number of passengers carried.  By this method you can compare the potential energy savings of one mode over the other on equal footing.

However I must also note that there is more to energy efficiency than just MPG.  To be fair you must also compare the energy consumption of the infrastructure that supports the two modes of transport.  Wich consumes more energy to build and maintain, a mile of interstate freeway or a mile of 79 MPH mainline track?  You simply leave this part out of your equations.

When you come up with appropriate facts and figures Paul you will see that trains are the most energy efficient means of land transportation.

 

Scott 

[HarveyK400]

Paul,

Thanks!

This points out the effect of the extra 132 tons being hauled around on the Hiawathas.

My concerns are whether there is room for a fast 300-passenger train in the rush hours, how to best accommodate the demand for longer-distance travel, and what is the cost of additional capacity for limited periods?

Another issue is the practice of focusing on maximizing revenue per passenger rather than increasing overall revenue and ridership more than cost.  The trains then can become a social tool to reduce less efficient driving, highway congestion, energy consumption, emissions, and consumer cost.  

You may be interested in an article, "Optimizing Aerodynamics to Raise IC Performance" by Jean-Luc Peters in the Oct, 1982 Railway Gazette International.  I was able to translate this into the Davis formula and program calculations using Basic.  Unfortunateley, Basic is obsolete and current programming languages are beyond this old dog.

Harvey 

[oltmannd]

Nice work!  I'll definitely have more to say later...

[Paul Milenkovic]

Starting with http://cta.ornl.gov/data/tedb26/Spreadsheets/Table9_10.xls, Amtrak's most recently-reported energy use is 2700 BTU/passenger mile, down from a high of 3200 in 2000 and up from a low of 2400 in 1991.  Using a figure of 125,000 BTU in a gallon of gasoline (the high heating value) and 140,000 BTU in a gallon of #2 Diesel, this works out to 46 passenger-miles/gallon gasoline (MPG will be gasoline unless indicated).  Their averages work out to 20 persons per train car.  A train car averages 2.6 Diesel MPG, contrasted with a figure of 6 Diesel MPG stated for intercity buses.

To put these numbers in perspective, I looked into some train resistance calculations - the Davis formula had been suggested on another thread.  My source for train resistance is S. F. Hoerner, 1965, Fluid-Dynamic Drag  Dr. Hoerner was a German aerodynamicist who emigrated to the US after WW-II.  The book was recommended to me by a Mechanical Engineering professor at Northwestern University when I had asked about drag numbers for determining the fuel economy of trains.  The book is self-published by the author, and I had ordered a copy from his widow at Hoerner Fluid Dynamics, PO Box 342, Brick Town, NJ 08723, but that was over 30 years ago.  But the laws of physics haven't changed.  Page 12-15 gives a chart for rolling resistance (Davis formula) and aero drag for a 400 ton train with "conventional" aerodynamics and with streamlining.

My baseline train is the Amtrak Hiawatha Service, currently operating a 5-car train with a P42 at one end and an NPCC (non-powered controlled cab) F40 at the other end.  The weight of this train is 525 tons -- 125 tons at each end and 55 tons each times 5 cars.  I am assuming the upper end of Dr Hoerner's drag numbers for this train, owing to the unstreamlined underbodies of the Horizon cars and the step mismatch between these lower profile cars and the locomotive or cab units at each end.

My first comparison train is a 10-unit Talgo consist (each Talgo unit is 45 feet long) with a Talgo XXI Power Car at each end.  I am assuming 20 tons per Talgo unit (somewhat heavier than the standard Talgo 17.5 ton unit for strengthening to meet FRA limits) and 90 tons each for the Talgo XXI Power Cars.  I am assuming the low end of Dr Hoerner's drag numbers owing to the streamlining and height match of the Talgo consist.  That consist weighs in at 380 tons.

My second comparison is a 5-car consist of a Colorado Railcars single-level DMU at each end (80 tons each) with three 55 ton trailers in the middle.  The CRC DMU is faired and streamlined and height matched, so I will assume the same aero drag numers as Talgo.  The CRC consist is lighter than Talgo -- 325 tons.  The CRC consist achieves its weight savings by carrying passengers in the power cars, which employ truck-type high-speed Diesels and fluid-drive transmissions, in contrast with the Talgo XXI, devoting two carbodies in the consist for propulsion with the weight of Diesel-electric drive.

For calculating fuel use, I am assuming that a Diesel engine uses .4 pounds of fuel per HP-hr, and that a gallon of Diesel weighs 7 pounds times 20,000 BTU/pound of hydrocarbon fuel giving 140,000 BTU per gallon of #2 Diesel.  I am using the Hoerner drag figures to compute fuel usage at a constant 80 and 110 MPH, and I am assuming that the Hiawatha train has to accelerate to that full speed four times.  The trip length is 86 miles.  I am assuming the the HEP requirements average to 40 kW per car, and that the total trip time that the HEP is in use is 1.5 hrs for 80 MPH, 1.25 hrs for 110 MPH peak speeds.

Assuming 500,000 passenger per year on the Hiawatha service, that works out to an average load of 100 passengers per train.  So if the locomotive gets 1 mile per gallon, the train averages 100 passenger miles per gallon Diesel or 89 passenger MPG (gasoline reference).  It is interesting that the passengers per car (average of 20) are at the Amtrak system average.  Many will consider these load factors low, but the Wis-DOT recently pushed for a 5th car on the consist on account of peak travel times, and they don't vary this consist with changes in traffic.

I label the trains Horizon for Hiawatha-Horizon cars, Talgo, and CRC DMU for Colorado Rail car DMUs plus trailers.

       Train Weight      Cruise HP                        Trip gallons (#2 Diesel)

          (tons)        80 MPH 110 MPH             80 MPH                       110 MPH

                                                Cruise+Accel+HEP= Total  Cruise+Accel+HEP=Total

Horizon   525          1377   2860            85+28+23 = 136          128+53+19 = 200

Talgo      380           645   1155            40+20+23 =  83            52+38+19 = 109

CRC DMU 325           583   1070            36+17+23 =  76            48+33+19 = 100

This works out to a max of 200/86=2.3 gallons/train-mile for the Horizon consist at 110 MPH, to 136/86=1.6 gallons/train-mile for the 80 MPH Hiawatha consist, to the best case 80 MPH CRC consist of 76/86=.9 gallons/train-mile.  As a sanity check on those numbers, I talked to someone at Wis-DOT about the Vision Report fuel economy assumptions, and I was quoted 1.7 gallons/train-mile for a single locomotive, an 8-car Amfleet-type consist, and no cabbage car.

Expressed as BTU/passenger mile / passenger MPG (gasoline equivalent)

                        80 MPH                        110 MPH

Horizon       2240 BTU/PM / 56 PMPG    3220 BTU/PM / 39 PMPG

Talgo         1400 BTU/PM / 89 PMPG    1820 BTU/PM / 69 PMPG

CRC DMU    1260 BTU/PM / 99 PMPG    1680 BTU/PM / 74 PMPG

The current Hiawatha is scheduled Mil-Chi at 1:35 Hr:Min -- my computer simulations of a 110 MPH Hiawatha give Mil-Chi at 1:15 Hr:Min.

OK, I have given you a topic.  Now discuss this amongst yourselves . . .