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, 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.
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
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.
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.
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.)
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.
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.
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.
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.
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
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.
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.
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...
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 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
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