Why are trains no longer streamlined ?

[TestDrive]

Originally Posted by Clev

Wow, and that number even includes partial cars, empty cars and switchers in the yards. Excellent find.

Can't cite a source, but some time in the last year or so - on the Discovery Channel or some such - I saw a segment on computer controlled engines & switches in switching yards. The engines propelled groups of loaded cars up to X.yz mph (Pulse) then release them and the car/cars would roll (Glide) up to 1/2 mile??? through a series of computer actuated switches to arrive with just enough force to auto-connect to a series of cars being assemble on a siding.

[Big Dave]

A loaded 100 ton car (gross weight up to 140 tons) at 1 MPH will coast for five miles on flat track.

BTW, railroad rolling stock is usually loaded 70,000 lb/axle. A four-axle car could weigh as much as 140 tons gross. All US freight locomotives have a traction motor for every axle.

Flat yards at night are often deadly for the unaware. That car is coasting along nearly silently. Switch yards work 24/7. This is why railroad detectives ("special agents") are very vigorous about trespassers.

Electrifying the mainlines is a simple but expensive proposition. It is old tech, well proven and available readily if not exactly off-the-shelf. Figure about $5 million per mile. Another $2 million per mile for the retrofit of electrical power transmission. About 32,000 miles of electrified mainline track would allow access to non-oil energy for 98% of railroads' energy needs. Figure that reduces the railroads quarter million barrel per day fuel appetite by 98%, but where do you get all that electricity?

[Bicycle Bob]

I think that the main reasons for diesel-electric drive are to avoid burning out a clutch on start-up, and to keep the whole train from jerking with each shift. The ballast is also handy for traction. Presumably, one could arrange for a separate mechanical drive for use at speed, with a burst of power from the inertia of the generator in lieu of a battery to power the electric motors during a shift on the mechanical transmission.

[Big Dave]

Why don't you check out the market for mechanical drives and see if you can find one bigger than 1300 HP? You won't find one. These are occasionally used on little 500 HP industrial switch locomotives but could never venture out on the mainline with the big dogs. No gear would stand the "buff" (fore-and-aft) pounding a train dishes out. Even in big mine haul trucks the standard is now diesel-electric.

Keep in mind on locomotives weight is not much of a limitation. Most locomotives use scrap iron and concrete to ballast them up to the commercial weight. So the weight of diesel-electric drive is no big deal.

[dcb]

Originally Posted by Big Dave

... Figure about $5 million per mile

Just curious, what does it look like after $7 mil/mile? Is it a third rail or overhead? Do the existing rails get retrofitted with more deliberate connections between the sections? Or do you have to lay a completely different track?

[Clev]

Originally Posted by Bicycle Bob

I think that the main reasons for diesel-electric drive are to avoid burning out a clutch on start-up, and to keep the whole train from jerking with each shift. The ballast is also handy for traction. Presumably, one could arrange for a separate mechanical drive for use at speed, with a burst of power from the inertia of the generator in lieu of a battery to power the electric motors during a shift on the mechanical transmission.

Don't forget reverse. Locomotives run at the same speed and efficiency in either direction.

You also get cool benefits like slugs, which are locomotives (usually obsolete models) with the prime mover removed (and often replaced with ballast) but the traction motors intact. The slug is attached to a regular locomotive, which can power its own electric motors, as well as those on the slug. They're used in switch yards and other situations where you need a lot of tractive effort, but not a lot of top speed.

[jamesqf]

Originally Posted by Big Dave

Electrifying the mainlines is a simple but expensive proposition. It is old tech, well proven and available readily if not exactly off-the-shelf.

Should be off-the-shelf, since a lot of European railroads are electric. I don't know about cost, but $5 million/mile seems way steep. It's basically just running an overhead power line along the track, and a quick search finds costs in the neighborhood of $50K/mile.

Figure that reduces the railroads quarter million barrel per day fuel appetite by 98%, but where do you get all that electricity?

If the conversion calculator - Fuel Oil Equivalent @Barrel (US) Conversion - I found is correct, you could run the entire system with 18 1-GWatt nuclear plants. Maybe with less than half that number, since I think the calculator is using total energy in a barrel, and not considering the less than 50% efficient diesel engine. On top of that, you could recover some energy through regenerative braking.

[Bicycle Bob]

It currently takes at least nine years of operation for a nuke to pay back the oil that has to go into producing and fueling it. As the ores are depleted, that goes up. We still don't know how many year's worth of oil it will take to keep the dead reactors and their waste away from the biosphere, but that's another expense the next generation won't be able to afford. Nukes are one of the least effective ways to save oil, and definitely the worst in terms of risk and deferred costs.

[Piwoslaw]

Some locos can use their electric motors as electrodynamic brakes.

[jamesqf]

Originally Posted by Bicycle Bob

It currently takes at least nine years of operation for a nuke to pay back the oil that has to go into producing and fueling it.

Why do you people go on repeating nonsense like this? Do you think we're all unable to do simple arithmetic?

Building a nuclear plant takes no more material or energy that building any other construction of similar size, and is roughly comparable to building the 2000 or so 1-MWatt wind turbines that would be needed to generate the same amount of power. If you use construction cost as a proxy for energy input, here's a wind energy site How much do wind turbines cost? | Windustry which puts the cost of wind turbine construction at between $1.2-2.6 million per MWatt, in the same cost per MWatt ballpark as a nuclear plant.