friedman@uiucdcs.UUCP (07/05/84)
#R:dciem:-96300:uiucdcs:20600012:000:1934 uiucdcs!friedman Jul 5 09:53:00 1984 Thanks to Mark Brader for the additional details on Toronto. My information is second hand. As to "tunnel" vs. "subway", I don't know; I would not have made such a distinction, but the information reported was supposedly supplied by TTC, and either they or Mass Transit could have used such a distinction without my realizing it. I would only quarrel with the statement that TTC's streetcar system is the last such on the continent. It is a very good one, and perhaps the most extensive surviving streetcar system. Mexico City also has a good one (I limited my article to USA and Canada, but Mexico is on this continent). And at least Philadelphia (10 routes) and San Francisco (5 routes) still include enough routes to merit the (subjective) noun "system" (as opposed to a one-route remnant, such as New Orleans) with significant amounts of street running. As to trolley poles vs. pantographs: I suspect that the real reason that trolley poles are going the way of the dinosaur, in favor of half-pantographs, is that a pantograph (or half) can't slip off the wire, as a trolley pole can. Junctions are also simpler, requiring no frog (that "thing" in the overhead that connects one wire from one direction to either of two from the other direction). I have seen a picture of an LRV of the San Francisco/Boston type (Boeing made) equipped with a trolley pole, but only for testing purposes on a system whose overhead at the time (I think it was Boston's) would not accept a pantograph. Obviously, if SF had wanted to, they could have used trolley poles on their LRVs, but I think the problem of losing the pole while in the subway probably made the difference. You're right, though, about the problem of crossing a pantograph line with a trolley coach dual-wire line; I can't think of any way to equip a TC with pantographs! I'm not sure of this, but I'll stick my neck out: I think SF may in fact have no such crossings.
stevel@haddock.UUCP (07/09/84)
#R:dciem:-96300:haddock:15300024:000:1021
haddock!stevel Jul 8 16:51:00 1984
Boston does have two Boeing trolley cars that have both a panograph and a
trolley pole at each end. Until very recently the Arborway line was all
PCCs with trolley polls while the rest of the system could run either
type. They have since modified the Arborway overhead to run panographs
out at least as far as the Northeastern stop. All of the work cars have
trolley polls and all of the trolley lines still support trolley pole
cars.
The Green line, the trolley line, has four different routes that converge
downtown and run together for about a one and a half miles. There is
also a totally seperate piece of trolley track, no outside rail
connections at all, in Mattapan. The trolleys are put on a truck to get
to the maintainance shop. Does this make a trolley system? Nearly all of
the route miles are seperate.
Rumor has it that one of the advantages, along with lower maintainance,
is that more power can be gotten through a panograph.
Steve Ludlum, decvax!yale-co!ima!stevel, {amd70|ihnp4!cbosgd}!ima!stevelhrs@houxb.UUCP (H.SILBIGER) (07/11/84)
Depending on the type of suspension used for the overhead (trolley) wire, a switch to pantographs may be possible. Some overhead wire systems use a "t" system to hold the wire. In the t system the support wire is straight, and a t shapped fitting holds the trolley wire, such that it is below the suspension wire ( at the bottom of the t.) In the u system, a fitting like an inverted u is inserted in the suspemsion wire, and the trolley wire is in the inverted u. In the t system it is easy to convert to pantographs, since there are no obstructions at the same level as the wire. With the u system, wich is used in Toronto, the trolley wire ends up at the same level as the suspension cable, and it is not possible to use pantographs without extensive changes. Crossings of streetcar and bus lines, when pantographs are used are handled by isolating the trolleybus return wire at the crossing. The bus is then not powered for that short distance. By the way, the half pantograph is called a Faively pantograph. Herman Silbiger