4 ms·

According to the DOT [1] it looks like my intuition is a bit out of date. Right now US freight about even, trucking still a little bit ahead by ton-mile. Ten ye

by saulrh 9y ago

According to the DOT [1] it looks like my intuition is a bit out of date. Right now US freight about even, trucking still a little bit ahead by ton-mile. Ten years ago rail carried 2/3 as much freight as trucks. Last-mile delivery on trucks (from the rail station to the point of use) is taken care of by the unit of measurement (one ton of freight traveling one mile), so I think that those numbers are relatively reasonable. So I'll admit: fair enough, the rail industry is still healthy and carrying a good amount of cargo. I'll withdraw the wording; we do not in fact use long-haul trucks for everything. The fact that trucks are competing with rail at all, however, given the geographical extent of the US and how horrible long-haul trucking is, I believe makes me stand by my claim that the US rail industry was broken and never recovered. It frankly astonishes me that driving something down the highway is even remotely financially effective in comparison to rail freight. And, of course, none of this is relevant to my original point: the railroads abused their powers to an astonishing degree and the government was forced to smash them for the good of the economy. Is it obvious to me that today's ISPs are following in the footsteps of yesterday's railroads and telephones and I don't understand how people convince themselves otherwise. [1] https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/publications/national_transportation_statistics/html/table_01_50.html https://www.rita.dot.gov/bts/sites/rita.dot.gov.bts/files/pu...

thinkloop 9y ago
It's wasn't obvious to me that trucking is much less energy effecient than rail. According to treehugger.com rail achieves "400 ton-miles per gallon whereas trucks currently hover around 130 ton-miles per gallon" [1]. I wonder why that would be - rubber tires vs steel-on-steel? Traffic? There isn't much traffic during the majority of a long-haul and the last few miles have to be done by truck anyway. [1] https://www.treehugger.com/cars/rail-versus-trucking-whos-the-greenest-freight-carrier.html https://www.treehugger.com/cars/rail-versus-trucking-whos-th...
- hirsin 9y ago
  Braking and acceleration - once you get x tons of anything moving, it generally wants to keep moving. Trains are tens of times longer than trucks, brake significantly less often, and have a lot more horsepower for acceleration.
  - int_19h 9y ago
    The other thing is, you can string wires along the rails relatively easily, and power everything directly with electricity - which offers substantial savings from efficiency of large scale power generation, even accounting for distribution losses. Better yet, you can then use regenerative braking, and feed energy back into the line. I do believe there's some benefit from the tracks themselves as well, though. Surely there's a lot less friction (per ton of weight) between the train wheels and steel rails, than there is between truck tires and the road?
    - libertyEQ 9y ago
      >you can string wires along the rails relatively easily, and power everything directly with electricity - Except all freight trains in the US have 6600 HP diesel engines, usually ~6-8 engines per 100 cars from what I've seen (which is mostly coal).
      - int_19h 9y ago
        US is an outlier in that regard. In other developed countries, railroads are mostly electrified.
  - em3rgent0rdr 9y ago
    I'd also say increased engine efficiency resulting from being able to have a bigger engine to move more tons.
  - pwg 9y ago
    Lowered overall wind resistance also plays a significant part. With Semi's, each separate truck has to endure its own wind resistance independently. With a train, each rail car effectively drafts the car in front, producing significant reductions in wind resistance for all cars behind the locomotive. This site (https://www.energy.gov/eere/vehicles/parasitic-loss-reduction-research-and-development https://www.energy.gov/eere/vehicles/parasitic-loss-reductio...) quotes wind resistance, braking, and rolling resistance as responsible for a 45% reduction in efficiency. This site (https://www.nap.edu/read/13288/chapter/7 https://www.nap.edu/read/13288/chapter/7) has a table that separates the factors out. Of the parasitic losses, aerodynamic losses (i.e., wind resistance) is responsible for consuming 53% of the motive power.
- emiliobumachar 9y ago
  A small part of it is air resistance. A train has a lot less frontal area per ton.

by saulrh 9y ago

thinkloop 9y ago

It's wasn't obvious to me that trucking is much less energy effecient than rail. According to treehugger.com rail achieves "400 ton-miles per gallon whereas trucks currently hover around 130 ton-miles per gallon" [1]. I wonder why that would be - rubber tires vs steel-on-steel? Traffic? There isn't much traffic during the majority of a long-haul and the last few miles have to be done by truck anyway. [1] https://www.treehugger.com/cars/rail-versus-trucking-whos-the-greenest-freight-carrier.html https://www.treehugger.com/cars/rail-versus-trucking-whos-th...

hirsin 9y ago
Braking and acceleration - once you get x tons of anything moving, it generally wants to keep moving. Trains are tens of times longer than trucks, brake significantly less often, and have a lot more horsepower for acceleration.
- int_19h 9y ago
  The other thing is, you can string wires along the rails relatively easily, and power everything directly with electricity - which offers substantial savings from efficiency of large scale power generation, even accounting for distribution losses. Better yet, you can then use regenerative braking, and feed energy back into the line. I do believe there's some benefit from the tracks themselves as well, though. Surely there's a lot less friction (per ton of weight) between the train wheels and steel rails, than there is between truck tires and the road?
  - libertyEQ 9y ago
    >you can string wires along the rails relatively easily, and power everything directly with electricity - Except all freight trains in the US have 6600 HP diesel engines, usually ~6-8 engines per 100 cars from what I've seen (which is mostly coal).
    - int_19h 9y ago
      US is an outlier in that regard. In other developed countries, railroads are mostly electrified.
- em3rgent0rdr 9y ago
  I'd also say increased engine efficiency resulting from being able to have a bigger engine to move more tons.
- pwg 9y ago
  Lowered overall wind resistance also plays a significant part. With Semi's, each separate truck has to endure its own wind resistance independently. With a train, each rail car effectively drafts the car in front, producing significant reductions in wind resistance for all cars behind the locomotive. This site (https://www.energy.gov/eere/vehicles/parasitic-loss-reduction-research-and-development https://www.energy.gov/eere/vehicles/parasitic-loss-reductio...) quotes wind resistance, braking, and rolling resistance as responsible for a 45% reduction in efficiency. This site (https://www.nap.edu/read/13288/chapter/7 https://www.nap.edu/read/13288/chapter/7) has a table that separates the factors out. Of the parasitic losses, aerodynamic losses (i.e., wind resistance) is responsible for consuming 53% of the motive power.
emiliobumachar 9y ago
A small part of it is air resistance. A train has a lot less frontal area per ton.