Fuel efficiency potential

[just-want-peace]

This thread - 35.5 mpg- what a crock!! - got me to thinking about an episode on TRAINS I saw a few weeks ago, with the following statement. This is exact, as I took a pic of the screen when it appeared cause it blew my mind away.

A modern diesel-electric locomotive can move one ton of freight an average of 202 miles on a gallon of diesel fuel. A modern 18 wheeler truck can only move a ton of freight 59 miles on the same gallon.

History channel, "MODERN MARVELS" - TRAINS

Factors:
1 Stopping/starting
2 Differing friction for drive wheels
3 Operator's driving habits
4 Difference in efficiency of engines
5 Difference in efficiency of drive train (truck) and transmission lines to motors (train)

I'm sure there are others, but these are all I could think of off-hand.

I know virtually squat about trains, but it seems to me that the huge factors would be #'s 1 & 2 for the difference in efficiency, UNLESS there is a tremendous difference for # 5.

IF #5 IS very significant, then this may be the answer to vehicular mileage, as the remainder would not change appreciably for the first 4 factors when considering the efficiency for "standard" vehicles.

Any "scientific" thoughts?

Incidentally, I had an '84 Cutlass Ciera (Olds) DIESEL that would get an average of 36-38MPG on the "I" at 70MPH.

Loved it - except for the acceleration. Excellent torque in the mountains & you couldn't tell you weren't on level ground performance-wise.

 

[Bob Alkire]

I don't know about the rail, but I've never driven or seen an 18 wheel truck that could move a ton of freight 59 miles on a gallon. My truck empty gets about 12 MPG at best and with a load on highway about 9 MPG and in town or city about 2 or 3 MPG.

If the rail could deliver on time, would do a lot to help them, or should I say faster. Then there is the cost to get to and from the rail yard with the load being pulled by truck.

 

[Mexdeaf]

"Efficiency" is not all measured by MPG. As Bob Alkire pointed out, there are time and placement issues also.

The most "efficient" means of transport for people is "mass" transport, if you speak of pure energy efficiency. But it is not the most efficient use of time or placement- that's why many large urban centers have traffic gridlock in spite of heavy reliance upon bus, urban rail, and subway modes of transport.

 

[windcatcher]

I think the estimates are a little low on the truck.....

An 18 wheeler....fully loaded, gross max including trucks tare weight plus cargo.... 80,000 lbs.: Average mpg is between 5 and 7, usually in the range of 5mpg diesel. That is moving 40 tons 5 miles for a gallon of fuel OR 40 X 5 = 200 mpg fuel per ton. Of course, only about 22 tons of that is actual freight.... the tractor and trailer account for the rest. The efficiency COULD be increased if federal and state highway regs allowed more maximum weight to be carried. Many a truck hauls less than a full load, volume capacity because of the density and weight of freight. However, the efficiency of the engine to pull the weight cross country and the efficiency of the braking mechanism in an 18 wheeler when properly maintained, means they are quite capable of running safely with higher weight than the law allows.... in most conditions. International, Cat, Freightliner, Peterbilt tractors, etc..... all are made very capable of pulling 120,000 gross pounds on the highway....... but they are regulated with laws to maintain weight including tare weight and fuel of less than 80,000 pounds...... with strict adherance to distribution over axles.

However, our highway system and those specially designed truck park areas, are designed to withstand the stress and wear of weight, relatively distributed over the axles and bearing of those 18 wheels of legal weight. As weight increases, the load stress on areas of paved road subject to slow downs and paved truck park areas is increased, and particularly where tight turns or pivots are required. As the weight is increased, there is slower gains to traffic speeds when excelerating, and greater distances required for a safe and controlled stop, but a professional driver is aware of these factors constantly changing in conditions beyond his own control.... like the weather, and is accustomed to making adjustments to properly control his equipment.

Ideally, the trucking industry would be supported with truck stops and full facillity rests areas along the interstate and major US highways...... and Warehousing and receiving areas located on the fringes of major populated areas so that local trucking services with smaller trucks would do the deliveries.... as they are more efficient in the stop and go traffic and ease of maneuverability of moving around in traffic. But this would require careful planning for development, and transitioning those areas of trade already trapped within municipalities from receiveing and shipping to other forms of productive use, and providing incentives or planned development for building receiving and shipping in more rural areas.