HVDC is not a practical technology for sliding power distribution – or for applications where very thick and heavy insulating construction cannot be provided. There are relatively hard limits on third-rail voltage imposed by its proximity to ties, ground, etc., particularly in rain or bad weather that induces a better path from rail to ground. The substantially higher return current in the track requires better bonding (and in my opinion leads to higher galvanic issues as well).
A possible place for third-rail service is on helper or pusher districts, to supply additional power via relatively cheap means. This would not ‘replace’ diesel operation over this trackage, simply provide a means of ‘boosting’ performance without commensurate fuel burn. I have looked into this opportunity, and some of the enabling technology should be quite inexpensive. I don’t think that third rail is a particularly good general railroad solution for long-distance full freight electrification, however; I also note that all current FRA development of electrification systems is predicated on relatively high-speed passenger operation, and 110mph operation on third rail is NOT a particularly attractive technical requirement…
The Harmon to GCT electrification was state-of-the-art… for the turn of the century. It is quite capable for passenger work, but even in its best days the speed achieved was not particularly high. I can’t imagine it extended to serve the needs of particularly heavy freight… or fast service either; it’s not at all easy to build a high-current high-speed pickup for conventional third-rail (either overrunning or underrunning) that fits in the required locations and won’t set the train on fire (as so many of the '50s attempts seemed to do!). You will also have some substantial engineering, implementation, and maintenance problems trying to do distributed peak-power generation with locomotives feeding third rail.
Conversely, modern AC catenary (the dynamically-suspended
If one were to start with a clean sheet of paper on railroad electrification, there are very interesting technologies which can improve the reliability and safety - whether cat or 3rd rail.
One is the application of computer controlled power dispatching. Under this system, most of the electrical system would be at very low voltage most of the time. In reponse to the train signaling system, with further control from dispatching, voltage would jump to railroad power levels a few seconds before the engines arrive in that block and then drop back to low control voltage after the engines had passed. This is very similar to the way that model railroads operate. Properly designed, most of the train would be over(under) dead power leads for safety.
The second idea requires much more research, but GM developed an inductive method for connecting the 220v charging power to battery powered cars. With this method, a person could be in contact with both the power source and the car at the same time - without causing a short or conducting power through the body. The only thing that would allow power transfer is a matching inductor in each locomotive.
Interesting. On the one hand, this method could reduce attenuation losses in the overhead wires. On the other hand, wouldn’t this type of system hamper the ability of downhill trains to return power to the system via regenerative braking systems?
Computer power dispatching doesn’t impair regenerative connectivity. Note that the dispatching system works in ‘blocks’ that are activated by train occupancy. A train doing regenerative braking is still occupying a block, and the same connections that provide high traction power to trains in a block can very simply be arranged to handle or sink the current from trains producing current instead…
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As to where would the electricity come from? OK, OK, you all have backed me into a corner and now I guess I need to come out of my closet: in my humble opinion, formed over working on and off in the power and risk assessment industry as an engineer for the last four decades or so, the power generation mode (for any industrially usable mode) which has the least overall cost to the environment (total environmental damage) and the lowest overall risk to the people, when looked at from initial extraction/acquisition of the energy in whatever form to the final user (which is the only valid comparison, by the way) is nuclear energy. Both the overall environmental hazard/damage and the overall risk to both workers and general population, particularly in terms of health consequences, are about two orders of magnitude less than the next best resource, which is natural gas. Coal and oil are simply off the charts, relatively speaking. The various renewable resources, while very attractive from some standpoints, either do not offer enough 100% reliable power (e.g. wind has this problem); enough power, period (e.g. biomass, geothermal) or have some pretty horrible environmental drawbacks (e.g. hydroelectric). Which is not to say they shouldn’t be used where, and when, they make overall sense. But from the engineering standpoint, nuclear is preferable on every possible count. Politically, of course… oh well.
For what it’s worth…
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Jamie
That makes two of us…
Great Britain is mentioned here, and if I am not mistaken France is big on Nukes. On top of that there are people that think brain cells are slowly fried if you get within a mile of HV Transmission Lines.
Yeah Jamie, but remember getting to yes often means that there is more than one answer, logic or no logic to what an engineer knows is the best answer there’s always a bunch that make up a majority that will shout him down. By the way, I’m an old Civil Inspector with Nuc/Fossill/Hydro (NFH) construction Certs (what used to be called Level II). I know your point and mostly agree with it. Unfortunatly more dissagree with us than agree. SRC as a by product may be a place to find some alliances toward getting the U.S. back in the Nuc business while we still have enough crafts persons that know how to do the work. That combines, Utilities, Coal miners, Railroads, Steel folks, buildiong and trades folks and not a few investors that know a good thing when they see it. I do have to give you this, I think your right - Roy
Third rail should be the solution for tunnels where raising clearances for caternary would be expensive. The third rail would be between the rails, Lionel like, and energized only when a train was in the tunnel. Voltage would be about 750V and this may require mutliple droppable “skates” to pick up the required current throught the tunnel. Just because the long distance transmission for the power companies would be DC, there is no reason why the say 20,000V catenary outside the tunnels need be DC if AC is the engineering solution for cost effectiveness.
I see too many objections on this thread that indicate the objectors have not really thought through all the possible answers to their objections.
Some of the electrifications may be planned for high speed rail, such as any further upgrade of the NE Corridor or its extension to Portland ME and Richmond, VA, although even there freight must be accommocated. But most new electrification would be planned primarily for more economy and greater capacity in freight movement, with residual benefit to commuter and Amtrak operations that may use part of this trackage
Yes but we are talking about (at least I think we are talking about) wiring up the entire U.S railways. NEC is fortunate but what about the other lines?
J- Dealing with ice, if the whole continent can be filled with overhead transmision lines all over the place, why wouldn’t the railroads be able to have catenary?
DaveK- Why would you put the 3rd rail between the rails Lionel like, instead of outside the rails like on subway lines?
Cantenary is possible but would be kind of difficult for double stacks and excess height railcars like the high cube box cars and the automaxes. Now if you raise the wires to accomidate them, you need to raise the clearance of the bridges and tunnels too. Gets kind of expensive and tasking to alter everything for the wires.
I don’t know if it is possible but I wonder if it is possible to do a combination. Wires for lines and third rail for tunnels and underpasses?
Most of the clearance work for DS was done by undercutting. Not too difficult to go another foot down, if you need to. Tunnels can sometimes be undercut, too, depending on their construction. And, I think some of the heavy duty DS tunnel work allowed some extra clearance for future “growth”. Stringing the wire is the big expense.
Like most of the actinide elements, Lawrencium (Lr, element 103, atomic weight 262), has only been observed under extremely specific conditions (i.e. inside particle-accelerating cyclotrons), and only a VERY limited number of times. You can’t just go to your friendly, neighborhood Lawrencium supplier and buy a tank of it to spray onto a pile of Plutonium. Lr was first detected in 1961 after bombarding a mixture of isotopes of Californium with heavy Boron. Moreover, it has a half-life of 8 seconds (although a lighter isotope had a half-life of 35 s)…not much time to make it useful, even if you had a lot of it. It has been observed so few times that is it considered probably a solid at 273 K (0 degrees Celsius), and probably would have a metallic look if you had enough of it to view it. We don’t even know how it would react with air or water.
As for bombarding P with Lr: I’d stand waaaay back. There would be very little that was inert about the particles that would be emitted.
(1) The cost of the changeover is prohibitive (pointed out justifiably multiple times)
(2) Why do people think that ALL the power put out at the generating site automatically gets to the end user(s)???
(3) Why do people think that electricity is automatically cleaner than portable diesel electric generators on wheels (aka diesel locomotives)???All you are doing is moving the emissions point source to some other guy’s backyard and evil is conserved.
I was able to ride one of your SEPTA trains a couple weekends ago. I was in Philly for a scientific conference, and I took the train from Pennsylvania Convention Center out to the airport. I talked to a British colleague who said he rode the train in from the airport and liked it a whole lot – SEPTA gets high marks from the international train-riding community.
Hey everybody, did you know you could fly into Phily, a $5.50 train ride leaves just outside baggage claim every half hour and can take you to Amtrak station where you can hop on the NEC? Trying doing anything that cool anywhere else. I hope the service holds together after the big cost crunch situation by the end of the year.
By the way, I remember riding a Silverliner MU car from Metro Park, NJ to Trenton about 20 years ago (a commuter train on the NEC), and I remember the acceleration and traction motor gearing to be streetcar/electric trolley bus kind of fast – the SEPTA MUs run smooth but I didn’t notice the same rush of adrenelin. Does SEPTA run the same kind of MU over its entire network or is it a mix of Diesel and electric like NJT? Who makes your MU cars these days now that Budd is out of the business?
Mudchicken you have a nice way of putting forth the $ 64,000 question. Said like a true student of human nature and professor of life as it really is, Good post!!!-----[^]
Junctionfan: I really did not want to say this, but it really would help if you knew something about the modern compliant coal fired generating plants which are the only kind you can build in the U.S. Please do also remember that those coal plants are a primary sorse of healthy income to your favorite industry in the U.S. (railroads). We do not have the resorses your great country has when it comes to Hydo electric sites in the U.S. and are even beginning to retire and destroy them due to their adverse impact on the environment. Be careful friend don’t cut yourself off from reality when it comes to commercial enterprises