Re: Fuel-Sipping Trains
- There are secondary effects that are not reflected in any of these
comparisons. For instance, a railway station within easy reach of
pedestrians will both be symptomatic of and increase the viability of
pedestrian-accessible destinations in general. Compared with car travel
there is therefore at worst a lesser tendency to generate a need to
travel. In practice there might well be a tendency to reduce the need
We all know how car-dominated environments create dependence on cars,
requiring that we take longer trips more often. A truer comparison
might be 1km by train to perhaps 8km by car, 7km of the latter
contributed solely by the sort of environment associated with that mode
of transport. Has anyone actually quantified this?
--- In email@example.com, Richard Risemberg <rickrise@...>
> > Fuel-sipping trains
> > June 11, 2007
> A 26 MPG Honda Civic fully loaded with five passengers?=v= In the U.S. cars are rarely filled to seating capacity.
> 130 passenger miles per gallon.
The average ridership is slightly over 1 person per car.
So it's hard to take numbers like that seriously.
=v= Also, wow, Honda Civics are way down to 26 MPG now?
=v= One complication in these comparisons is that passenger
rail in the U.S. has very little dedicated track. For the
most part Amtrak runs on track owned by freight companies.
=v= Another complication is that Amtrak is subject to a dogmatic
"business model" that competing modes are not. The ideology is
that Amtrak should turn a profit, and there's a budget fight for
its small subsidy every year. So service keeps getting hurt and
the trains do such things as haul freight along with passengers
(preventing a switchover to lighter trains).
=v= Meanwhile, of course, cars and planes enjoy a staggeringly
high and rarely-mentioned subsidy.
- There is an accountant joke I once heard where three accountants are
applying for an executive position. The CEO of the company asks
each of the candidates what is 2+2. Two of the applicants says 4
and don't get the job. The third, who gets the job, asks the
CEO, "What do you want it to be?"
I am not aware of any studies that would answer some important
questions raised in this discussion and in the larger discussion
about funding for rail.
The laws of physics say that the faster an object moves through
space the more resistance it will encounter, therefore, more energy
is required to achieve higher speeds. I am sure that the field of
aero-dynamics has can provide formulas to quantify this in terms of
frontal area and speed. What is lacking is a quantified functional
relationship of increased weight and drag from adding one additional
coach car to a train-set. Intuitively, it seems that adding cars
(therefore, more passengers) would add a very small increase in
energy usage while greatly improving the passenger- miles/gallon
ratio. Therefore, one could state the passenger- miles/gallon to be
anything they wanted to by adding or subtracting the number of
coaches/passengers per train. There are of course practical limits
to how long a passenger train can be in terms of station platforms
and crews. In addition, at some point the weight of the train will
require an additional locomotive which alters the equation.
I have heard passenger miles/gallon figures that are all over the
map. Until someone does some hard science on this that deduces the
issue to friction of steel wheels on steel rails vs. rubber wheels
on assault. I suggest that we look at any calculation of passenger
miles/gallon will a great deal of skepticism.
- This is all pretty tangential. The basic physics are:
It takes lots of energy to accelerate a train, and the
total amount of that energy increases with the SQUARE
of the speed.
It takes lots of energy to drag trains up hills; this
is related to weight and elevation, not to speed.
Long, thin objects have high "Reynolds Numbers" which
means that the amount of air drag is considerably lower
than for short, fat objects.
Mass of a train has no effect whatever on the amount
of aerodynamic drag.
Light, long, streamlined trains are the most efficient.
Slower trains are more efficient than faster ones, all
other things being equal.
Again, the TGV double-decker gets good efficiency despite
its very high speed.
----- ### -----
J.H. Crawford Carfree Cities
- Actually, this brings up a question I've been wondering for some time. In an era of dwindling
oil supplies, are we better off with jets or ships? 747 or QM2? Or is there another solution?
> "The obvious replacements for planes are scarcely better. Fast passenger ships appear tobe even worse for the environment than jets. ... [Paragraph] Nor are ultra-high-speed trains
the answer. Though trains traveling at normal speeds have much lower carbon emissions
than airplanes, Professor Roger Kemp of Lancaster University shows that energy consumption
rises dramatically at speeds above 125 miles per hour. Increasing the speed from 140 to 220
mph almost doubles the amount of fuel burned. If the trains are powered by electricity, and if
that electricity is produced by plants burning fossil fuels, they cause more CO2 emissions
than planes. Running trains on renewable electricity is certainly possible, but this faces
problems: Trains must run on time, and that means there is little room for 'demand
management,' which means reducing the electricity load in response to fluctuations in
supply. In all transport systems, high performance is incompatible with low consumption.
The faster you go, the more energy you need."
- On Jun 17, 2007, at 8:40 PM, Matt Hohmeister wrote:
> Actually, this brings up a question I've been wondering for someShips do not have to be powered by oil or coal. Highly refined
> time. In an era of dwindling
> oil supplies, are we better off with jets or ships? 747 or QM2? Or
> is there another solution?
sailing vessels with solar auxiliary power for days of calms and for
harbor maneuvering can move considerable tonnage and numbers of
passengers. However, it is obvious that if we are serious about
sustainability, we will have to accept that international trade and
travel will be slower and more expensive. (Although someone, upon my
telling them this, suggested that sail transport labor costs could be
lowered by using crews of slaves...I hope they were kidding.)
And no, I don't think nuclear-powered ships are the answer!
"...it is obvious that if we are serious about sustainability, we
will have to accept that international trade and travel will be
slower and more expensive."
Precisely. I know Joel Crawford takes a somewhat contrary position in
his book, but I'm a firm localist. Pedestrian cities and localized
economies are perfect for each other. Indeed, the one only comes to
full fruition in the context of the other.
--- In firstname.lastname@example.org, Richard Risemberg
> On Jun 17, 2007, at 8:40 PM, Matt Hohmeister wrote:
> > Actually, this brings up a question I've been wondering for some
> > time. In an era of dwindling
> > oil supplies, are we better off with jets or ships? 747 or QM2?
> > is there another solution?for
> > Anybody?
> Ships do not have to be powered by oil or coal. Highly refined
> sailing vessels with solar auxiliary power for days of calms and
> harbor maneuvering can move considerable tonnage and numbers ofand
> passengers. However, it is obvious that if we are serious about
> sustainability, we will have to accept that international trade
> travel will be slower and more expensive. (Although someone, uponmy
> telling them this, suggested that sail transport labor costs couldbe
> lowered by using crews of slaves...I hope they were kidding.)
> And no, I don't think nuclear-powered ships are the answer!
> Richard Risemberg