Dave,
Thanks for the description of the surface contact system. While it does sound cheaper (well, maybe) to install and operationally more flexible than the conduit system, it also sounds like a royal maintenance headache. I think you are right on the money in saying it is not compatible with grass.
- Erik
HaRakevet means The railway or railroad in modern Hebrew, with Rakevet HaKala meaning The Light Railway.
If anyone wishes to subscribe, you can easily the web address or contact me at
daveklepper@yahoo.com and I will provide the information.
But if anyone reading this is currently a subscriber, and has read or has issue No.80, please contact me. Thanks!
The system referred to by the Jerusalem Post was not the conduit system but a surface contact system with the conducting strip about two milimeters above the pavement surface and control boxes that sense when a rail vehicle is directly above and that powers the segmant only when the car is directly above.
That's what I was referring to as the conduit system - which was the term used by the transit industry 100 years ago. (look at any electric railway engineering textbook or handbook from that era). The conduits were often re-purposed cable car slots.
Several cities in Europe and USA had underground electric vaults built in the early 1900's into the center or along side of the rail lines for the collection of power to move the streetcars. These vaults were like the cable car vaults except that the electric wire or rails were attached to the side walls of the vault with one side the positive and the other the negative source of power. Each car had a "Plow" which extended from the car into the vault with spring loaded "shoes" pressing against the power wire or rails. The power was transfered to the controls of the car from one shoe then back to the ground with the other shoe. These systems were more expensive to build and maintain than overhead wire systems, but were required for clear views and esthetic reasons in many capital cities, Berlin, Paris, Washington DC and others.
As with many underground systems where electric is exposed to the weather and wet conditions they did not function well without much repair, maintenance and most were removed after a very short time. The system in Washington DC lasted until 1950 when the streetcars were removed and replaced by bus transportation.
Firelock76 Dave K's comment about ground contact reminded me of the old Washington DC trolley system. Now that was a bit before my time, but the DC trolley system ran on ground contact, the contact being in a "trench" below the road, DC not permitting any overhead wires. What Dave said about the pitfalls of such a system is correct though, the DC system was on paved streets and not through grassy areas.
Dave K's comment about ground contact reminded me of the old Washington DC trolley system. Now that was a bit before my time, but the DC trolley system ran on ground contact, the contact being in a "trench" below the road, DC not permitting any overhead wires. What Dave said about the pitfalls of such a system is correct though, the DC system was on paved streets and not through grassy areas.
From the sounds of it, the ground contact system may not be the same thing as the conduit system used in DC. The "segmented rails" seems to imply the running rails are powered as in a scaled up version of two rail power for model trains (I may be way of on this), where the rails are only energized when a train is in the segment.I don't see this or the conduit system as having any initial or operating cost advantages with respect to overhead wire.
FWIW, there was a book published in the mid-70's titled YV88, an Eco-fiction (eco-fantasy was more like it), that described what I think is the ground contact system. The authors had proposed spring supported rails above feeder conductors, where the weight of the electric railcar would compress the springs and initiate contact between the feeders and running rails. The book did get a couple of things right, fiber optics for communications and computer bulletin board systems.
To Falcon48: Oh yeah, what you said about salt and underground contacts is totally correct. I suppose what made the DC system workable was the fact that winters in Washington are usually prettty mild, snowfall and ice typically aren't much of a problem. Of course, the DC trolleys have been gone for decades so it's a moot point anyway. I'm not aware of any other city in the US that used that kind of a system.
Trouble with paved streets and underground conduits is that, in most places in the US, they use salt in the winter. Salt's really bad on under street conduits.
Dave, can you give us a literal translation of RKV (did I get the root right?) (HaRakevet)?
Johnny
In the 9 December magzine section of the Jerusalem Post, a reporter said that use of ground contact as developed by Bombardier would have saved money be eliminating the need for the overhead wire, as well as improving esthetics next to the Old City Wall. I wrote the Post Letters Editor and the reporter with the correction, noting that ground contact systems are more expensive becuase of the complicaton in track construction, plus the need for maintenance and inspection of the automatic devices that power the segmented rail only when the rail vehicle is over the segment. I also pointed out that the system isn't applicable to the area next to the Old City Wall, because this area is grassed, including over the ties between the rails, and there are trees as well. Wet grass and fallen leaves to not make good insulators! The track would have to be paved, with a net esthetic loss in my opinion. The reporter said she doesn't claim to be an expert. But she did accept a freebe trip to Germany to see the new Israel Railways double-deckers under construction at a Bombardier plant there. So far, no correction has been printed.
Also, she has contributed for years to the magazine HaRakevet. I had planned to subscribe to this magazine, but came across a piece in issue No. 80 that affects me directly here in Jerusalem and again has some bad distortions of fact. I would like to subscribe, and if any reader wishes to help me, he or she can contact me at: daveklepper@yahoo.com. I will explain the problem, and then you can tell me if any correction should appear. Thanks..
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