John WR I'm surprised no one has mentioned another aspect of modern street cars: Their ability to be powered for short distances by either a battery or a capacitor. It seems to me this is a very important improvement, especially in certain places.
I'm surprised no one has mentioned another aspect of modern street cars: Their ability to be powered for short distances by either a battery or a capacitor. It seems to me this is a very important improvement, especially in certain places.
I see capacitors being used more for peak load shaving than for eliminating wires. Capacitors make the most sense with very frequent charge/discharge cycles,e.g. absorbing regenerated power during braking to a stop and a boost for acceleration after the stop. It may make more sense to put the capacitors lineside near the street car stop so the cars don't have to expend energy to haul the capacitors around.
- Erik
Not to turn this into a discussion about last winter, but the polar vortex chilled down the great lakes to a point that they were acting as a heat sink which has kept the weather way cooler than normal for spring. You've heard about the backlog of grain that wasn't being shipped by rail over the winter? One of the reasons was that the lakes were frozen over later than normal. Thunder Bay is where most grain gets shipped from and it just wasn't happening. The farms and elevators had grain with no place for it to go as the silos at the port were full and couldn't be emptied. It was cold, so much so that people were getting a bit punchy from it. Now, back to our regularly scheduled discussion...
But Toronto doesn't have the strong wind the Chicago has off Lake Michigan. Even though Chicago is sourth of the Twin Cities, I found it colder in winters. And definitely colder than Toronto.
Toronto has a mild climate? Man it was COLD here last winter! Polar vortex and all that! There is a new streetcar on the TTC right now for testing purposes and it's a spiffy one! It has both poles and pantographs. Not sure if the plan is keep the simple one-wire system or to move to catenary, or if catenary will be used on the newer lines they plan to build. Hopefully they'll be running in my lifetime like the electric GO trains the politicians keep jabbering about. We just had a provincial election and the conservative candidate, Tim Hudak was going to fight congestion and gridlock by cancelling any light rail plans for Kitchener, Hamilton, Mississauga and Toronto and widen the highways. Suddenly, it's 1956! What a maroon and no wonder he lost.
Toronto is further south than the Twin Cities, and has a rather mild climate compared to the Twin Cities, Milwaukee or Chicago.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Low-floor cars will work just as well as high-floor, and both require the right kind of snow-fighting equipment. Many high-floor cars still have nose-supended traction motors that are only inches above the pavement. Only steam locomotives cqn do better, with diesel-electrics having the same problems as LRV's. If municpaiities don't have the right kind of snow-fighting equipment, trolley museums have examples of sweepers and plows that did a good job and can be replicated.
aricat Good luck Milwaukee, Grand Rapids, Detroit and Toronto; these low floor streetcars might work in places like Portland, but not here. These cities all get substantial snow every winter.
Good luck Milwaukee, Grand Rapids, Detroit and Toronto; these low floor streetcars might work in places like Portland, but not here. These cities all get substantial snow every winter.
is getting 204 new low-floor streetcars, starting this summer
The overheard wires had to be tweaked as well so that the trolley pole used to draw power is able co-exist with the new car's pantograph system when it goes live in the years to come.
Patrick Boylan
Free yacht rides, 27' sailboat, zip code 19114 Delaware River, get great Delair bridge photos from the river. Send me a private message
Dave,
No doubt most modern streetcars do not use batteries or supercapicators. But the fact that they are available can make them very important. After all when electric locomotives first were made they were used only to pull trains through tunnels. Then their use expanded.
And while neither batteries nor capacitors are new to streetcars the new lithium ion batteries are new.
Neither of the LRT lines in the Twin Cities falls into Mr.Gretner's definition of modern streetcar. One thing that Gretner implies is that modern streetcars must have accessibility for the disabled and seniors at street level. He mentions a two foot clearance from the street. That qualification would make the modern streetcar impractical in any city in North America which has substantial snowfall like the Twin Cities. Low floor streetcars just wouldn't work in my opinion. They among other things would be dependent on municipal snow plow crews to clear their right of way on city streets. Good luck Milwaukee, Grand Rapids, Detroit and Toronto; these low floor streetcars might work in places like Portland, but not here. These cities all get substantial snow every winter.
Supercapacitors are new technology but batteries go way back in street railway history. Most modern streetcar and light rail lines use neither, but depend on continuous power from overhead wires. There are exceptions, mostly because of historic districs. Oher variations do include dual-mode diesel and pure electric, and a modern adaptation of the pavement stud system, sort of a discontinuos in-the-street third rail that is only powered when the car is above.
Memphis does not use poles on vintage cars, and all cars have pantographs under "constant-tension-single-wire catenary." Charlotte uses poles on vintage cars and pans on modern cars under "constant-tension-messenger catenary." (And I agree, Richey's definitions are just as sensible.)
Yes, in passenger service, when the E Embarcadaro Line has operated, and will begin regular operation in 2015, the E historic cars share the Third Street tracks with the T line that uses the Brada LRVa. In addition, historic cars run on the J line for pull-out and put-in. The Milan cars are kept at the carhouse with those serving the T line . But none of this is constant tension. Neither were SN, Key, or CCT. Possibly San Joe is, however, and Charlotte and Memphis as well. I think the German exampe with TT's sharing wire in the subway may be in Essen. Subway wire is usually not constant tension, becuase the supports are frequency enough so there is no real point to it..
The frog the tansitions the pole from one wire to another is pretty simple, not rocket science by any means.
Dave, I'm pretty sure Phoebe Vet's talking about Charlotte NC.
I'm not sure if San Francisco's pole equipped PCC's and pantograph equipped LRV's ever have to share wire. Does anybody know?
I had ridden in the early 1980's pole equipped antiques in San Jose which did share the same wire with their pantograph equipped LRV's.
And I think I saw photos and videos of European double pole equipped trackless trolleys sharing wire with pantograph equipped LRV's, including one European, probably German operation where the trackless trolleys ran in the subway sharing the same right of way as the LRV's. I think it was a trains.com thread that gave me the youtube link, unfortunately I can't find it now on youtube search.
Don't go on. Please please, which system are you watching? Is this Memphis? Can you photograph the frog at the overlap point between two wires? I'm glad to know that this kind of frog is actually in use.
Further, the gauge of contact wire or messanger and contact wire depends on many things. In Jerusalem, our "single-wire-constant-tension catenary" is very light because there are connections to the feeder cables about every fifth span, about every 450 feet or 130 meters. And of course feeder cables are used for the ground return, so the rails do not do the whole job. And the rails are insulated from the ground, by the vibration reducing resilient liners and pads, to eliminate any stray current corrosion of damp old pipework and conduit and to eliminate any interference with ground-return communications systems.
Dave
Lackawanna Route of the Phoebe Snow
Slidning gentel and long frogs joining the two wires at the pull-off weigiht or spring-for-tension point. The frog slides on one wire and is fixed to the other. I confess I do not know of any operating example, but it can be done.
I have to stand corrected. The following you tube of the NEC somewhere between New Brunswick and Trenton shows a traveler wire on the PRR style CAT. Note you can view the messenger connected to the traveler connected to the contact wire.
https://www.youtube.com/watch?v=c4gOHCq3geg
Couple more points
On installations where there is only a trolley wire the trolley wire will have a larger diameter to carry the current since there is no messenger or traveler to share supply to short sections of contact wire. So the contact trolley wire at Boston South station will be thicker than the CAT contact wire in the country. Also contact wire can be smaller when the voltage is higher with the 25 Kv system able to carry 4 times the power that 12.5 Kv can It would be interesting to know MNRR contact wire diameter compared to the New Haven - Boston section.
Do not have any information as to various messenger wire compositions. Copper contact wire and some other conducting material for messenger would have different co-efficients of expansion, Have noted that constant tension section ends sometimes have a bar at the end which is attached top and bottom to the messenger and contact wires. Attachment to the weights is at the middle of the bar. That would keep both in the same tension. Interesting engineering problem.
LehighLad I can find nothing in Richey re trolley wire shared by pole and pantograph equipped cars.
I can find nothing in Richey re trolley wire shared by pole and pantograph equipped cars.
You are correct as far as it goes. A pan can work on trolley wire as long as the wire holders are all of the design that has the trolley wire below the holders. The cross support wires of the trolley wire must be a certain distance above the plane of the trolley wire(s).
Trolley poles with either graphite sliders or rollers can only work on CAT if all contact wire is connected together for contact poles to maintain their staying on contact wire. Usually there are short (6" ? ) insulation sections to separate different power sources
How that could be done with constant tension CAT is unknown since each section is separate ?
P.S. to Dave - - apology accepted.
I can find nothing in Richey re trolley wire shared by pole and pantograph equipped cars. As you mentioned, the classical "ear" (and Z-leg pulloffs) cannot be used (because the span wire needs to be well above the pantograph to avoid entanglement). Don't know whether an old Ohio Brass catalog would show the more versatile hanger or whether it's a modern (post-Richey and now for new LRT equipment) development.
There was a contract in the last decade or so to replace the 100-year-old "gas-pipe" triangular catenary on the old NYC to New Haven trackage. I believe that the upgrade has been completed, since I saw no evidence of the old configuration on Acela trips from DC to Boston in December 2012 and January 2014. What is interesting is that many of the century-old steel-lattice towers are in still place, a lot with the lower part encased in new concrete, obviously to strengthen a rusted-out base. There are plenty of new towers too., don't remember if they're lattice or just H-columns, or both.
gardendance I thought catenary was a line between 2 points with equally spaced weights. Zero is a weight, so trolley wire with no weights sounds like it can also be catenary.
I thought catenary was a line between 2 points with equally spaced weights. Zero is a weight, so trolley wire with no weights sounds like it can also be catenary.
Correct. A mathematical catenary hanging formula is any constant density wire, rope, etc between two points. A trolley wire does hang by that math formula. Wire has morphed by the electric traction business into being simple trolley when only one wire provides the only connection to power pickup.
Next we have PRR and New Haven RR type CAT. There is a powered " messenger " wire above the contact wire. The messenger is connected to each cross arm but does not hang as a catenary because: There are hangers from the messenger to the contact wire which holds the contact wire as a catenary between each hanger. That allows for much less distance between hangers but the sag between hangers is still a catenary formula. Since the messenger is attached at each cross arm the term is variable tension since the tension changes with temperature changes with much more sag in summer time. The messenger helps provide power to contact wire by the hangers.
Then we have constant tension CAT. A section of approximately 1200 - 1500 feet is built. The center of the section is attached to the cross arm for both messenger, contact, and sometimes another wire ( traveler ) . All other connections of the wires go thru rollers. Then at each end of a section the 2 or 3 wires are connected to a weight system that keeps the section in constant tension. To further keep the contact wire level the traveler if installed will attach to the messenger and the traveler will have connectors that may only be 1 - 3 feet apart connecting to the contact wire. That way contact wire is almost level but still hangs between connectors by the catenary formula.
Note: each section overlaps the next section by slowly rising above the next section.
The New Haven - BOS is constant tension CAT but South station in BOS terminates as a simple trolley since that is not high speed location
Once upon a time an article said "Catamaran tower". I don't know if the reporter misquoted the railroad spokesperson.
You are correct, Richey is a good source and an excellent book. I am glad you have it. It has been a long time since I had the pocket ediiton in my pocket. He has one definition and the standard dictionary another. I should apologize. But he is not the only source, and the terms single-wire catenary and messenger catenary and compound-messenger catenary and triangular-messenger catenary (any left on the old New Haven?) all used. in the industry
Does Richey cover the case of pantograph and trollely-pole operation sharing the same wire? Not only Key System, but Sacramento Northern, and Central California Traction. I think New Jersey Transit's Newark Division, since the transition from trolley pole operation to pantographs during the PCC era did not happen overnight. A special type of hanger is required, but it should not be more expensive than a regular trolley-wire attachment "ear." And "messenger catenary" is no problem except for the required "frogs" which require gently ramped sides and are thus larger, to handle the pantographs at switches and diamonds.
Guess I never expected to be accused of making up my own definitions, but maybe should have been aware it could happen given the adversarial nature of many posts. (Has the Goose been silenced?)
To support my position that a single trolley-wire system is not properly termed catenary, consider the following extract from Albert S. Richey's "Electric Railway handbook", McGraw-Hill, 1924 (2nd ed.), pg. 550: "Overhead trolley construction may be classed as (1) direct suspension, or (2) catenary suspension. Direct suspension comprises construction in which the trolley wires are attached, by suitable devices, to the main supporting system. Catenary suspension comprises construction in which the trolley wires are attached, by suitable devices, to one or more messenger cables which in turn are carried (a) in simple catenary by the main supporting system, or (b) in compound catenary, by secondary messengers which in turn are carried by the main supporting system."
Enough said.
The dictionary defintion of a catenary is the shape of wire or rope suspended between two points with the straight line distorted into a sag because of the weight of the wire or rope. Outside of railfan talk, professonals worldwide do use the terms single-wire catenary and messenger-and-contact-wire catenary. I have zero objection to railfans making up their own definitions, but you should be informed about what the profession states the term to mean.
I do agree the messenger catenary has been badly misused, and the worst case is Main Street downtown Buffalo. Absolutely inexcusable. Looks like they were going to run a Deutsches Budensbahn high-speed train under the stuff. Compare that with our beautiful and light single-wire catenary on Jaffa Road In Jerusalem. The North Shore had messenger catenary on the Skokie Valley line, but still ran 80mph north of North Chicago Junction to Milwaukee under simple wire, and with trolley poles and shoes yet! And now, with constant tensioning systems available for both single wire and messenger catenary, lighter construction is achievable with far fewer wire breaks and less pantograph or trolley shoe wear.
The green and yellow trolley cars are not operating under catenary but rather only under trolley wire, a single-conductor system. Catenary is a double-conductor construction which uses a hanging "messenger" wire from which "droppers" are attached to support the trolley wire, and keep it horizontal, thus aiding in keeping the current collector (trolley pole or pantograph) in continuous contact under high speeds.. The term "catenary" originally referred to a cable or chain hanging under its own weight. And yes, I do know that the trolley wire in the picture is sagging under its weight but nevertheless that type of construction is not properly termed catenary.
Streetcar systems used only trolley wire from their advent in the 1880s until high speed interurban transport developed in the early years of the 20th century and often employed catenary. In the 1950s I rode high-speed interurban trolley cars (capable of 90mph upwards) operating under (double-conductor) catenary installed circa 1912. SEPTA's Media and Sharon Hill lines in suburban Philadelphia now operate pantographs under trolley wire but classical trolley wire systems need to have the insulating hangers changed to accomodate pantographs. The picture shows the proper type used to allow pantographs, which as current collectors on RR lines here and abroad normally use catenary (e.g., Amtrak's NEC). Many new light rail lines unnecessarily use catenary (lacking high speeds) which ups the infrastructure capital cost considerably.
Hopefully the above will be informative (eliminating the confusion of terminology heretofore) and deter any need for a riposte.
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