I noticed this in another thread
There are only few real Bus Rapid Transit Systems Out there...
daveklepper wrote: The Seattle Bus Tunnel has reopened, and during the night when buses aren't running, light rail for intended dual use is being tested. The buses are now GM Hybrids, with battery as well as diesel power. The former dual trolleybus overhead is now all positive, both wires, with pantograph operation at 1500V DC.
The Seattle Bus Tunnel has reopened, and during the night when buses aren't running, light rail for intended dual use is being tested. The buses are now GM Hybrids, with battery as well as diesel power. The former dual trolleybus overhead is now all positive, both wires, with pantograph operation at 1500V DC.
I'm familiar with Philadelphia and Toronto, which once uipon a time had streets with both streetcars and trackless trolleys. In Philly the only street with this situation was Wyoming Ave, Toronto had a bunch of streets with both streetcars and trackless.
In some cases they used separate sets of wires for the streetcar and the trackless, probably to allow the trackless to pull over to the curb, while the streetcar stayed in the street center. But in some spots they just used 1 set of double wires. The streetcars used 1 trolley pole on 1 wire for half of the electrical circuit, the other half of the electrical circuit used the running rails. The trackless trolleys used 2 trolley poles and each half of the electical circuit went through each wire.
So what does one do when the streetcar, or light rail, uses a pantograph? Does anybody know of any such installations, where pantograph LRV shares the same street with 2 pole trackless trolley? I see from daveklepper's post that Seattle has decided not to try to mix double trolley poles and pantographs. Does anybody out there know how one could? I imagine that one would need separate wires, and that the LRV wire would have to be appreciably far away from the trackless trolley wires.
If this is true, does anybody know what the plan had been in Seattle? When they built the tunnel I thought the intent all along was to convert to rail, so were they planning all along to have mixed rail and rubber? Had they allowed enough space in the tunnel for all the wires they'd need to do both?
Was the intent to have the rubber not use wires, as is the case now? I'm also assuming that hybrid technology has advanced since Seattle started dreaming up the tunnel, so was the state of the art at the time good enough then, or were they gambling on future technology?
And does anybody know of any tunnels with mixed pantograph LRV and electric rubber tired buses?
Patrick Boylan
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Can't speak to Seattle's operation, but this video shows a European mixed use tunnel with both LRV (pantograph to single contact wire) and trolleybus with double wires held far to one side of the tunnel (where the pantograph wouldn't likely reach).
The initial part of the video shows the dual use, the middle of the video shows better detail in a lighted station where you can see the trolleybus poles at an extreme angle.
http://www.youtube.com/watch?v=d1EQkObn55I
Paul F.
That is one way. Another way is simply to center one wire, positive, for both pantograph and trollybus, and the negative wire only off to one side. Marseiilles and London (bow collector) were both examples.
Currently, both wires in the Seattle Bus Tunnel are positive for the light rail cars which are being tested. Only Hybrid buses with battery power now use the tunnel. Some Breda dual-mode buses that opened the tunnel have had the electric drive equipment removed and are being used as regular diesel buses, while a few are t he reverse and run as pure trackless trolleys.
Does anybody know what Seattle's original intent was?
In other words when they were designing the tunnel, had they planned to keep it all electric with current collection, and if so had they properly planned for enough space to have the wires separated enough? Or was the plan to do what they're doing now, electric with mixture of overhead current collection using the existing 2 wires for the steel wheels and hybrid for the rubber tires?
Was the level of hybrid, flywheel or battery technology good enough when they designed the tunnel, or were they gambling at the time that it would improve enough to be practical? Is it practical now?
You mention the hybrid buses are battery power, is that similar to what I think is the case in automobiles like Toyota Prius, conventional engine + battery and electric motor + system where the car decides which is best? What system does Seattle use that decides when to turn the conventional engine off and on? I'd assume one part would be rather simple, turn the engine off when you enter the tunnel, don't turn it on until you leave.
A little bit of an aside, all other things being equal automobiles usually get better gas mileage in winter because in warm weather one usually runs the air conditioner, while the conventional engine heaters use waste engine heat. A Toyota Prius owner friend says the optimization system shuts the engine off before it gets hot enough to make passenger heat, so he doesn't get the same gas usage improvement in winter that a conventional engine does.
The original intent of the bus tunnel was to use the positive wire for both light rail and trolleybus, and the negative wire only for trolleybus. The deisgners did not do their homework. Testing found that the return through the steel rails (instead of the negative wire) would interfere with Seattle's telephones, since the grounding impedance was much too high. So the track had to be rebuilt. They lowered it at the same time for level boarding of both the new hybrid buses and the light rail cars from the existing platforms. The original designers did not think about pantographs but simply remembered the old Seattle trolleypole operation.
Again, currently, all the buses are hybrids, using battery power in the tunnel, with occasional use of the diesel away from stations, to insure no dead batteries. The basic principle of the operation of these buses is like a hybrid automotible, but instead of the electric motor-generator (motor that is a generator when charging the battery and braking the bus or car at the same time) and the diesel both driving the conventional drive train, gearbox, differential and all, instead these buses use an electric motor/generator only driving the drive train, and another generator-alternator on the diesel. The operation is somewhat like a diesel locomotive, except for the added batteries, and instead of dynamic braking with electric energy going to waste as heat, is charges up batteries, which can then be used to power the motor instead of or in addition to the alternator attached to the diesel. The Toyota system (most other automakers' hybrids) is called a parallel system, while the Seattle buses and those on the MAX line in Las Vages and the hybrids in New York City are the series system.
The buses that opened the Tunnel, use before it was remodeled for light rail and dual use, were Breda buses that were not diesel electrics in the sence that locomotives were, but were dual mode with the operator choosing electric powering the drive train or diesel directly powering the drive train. No energy storage waws available, and in the electric mode the buses were like typical articulated trolleybuses, but a lot heavier.
I had argued strenuously that lower the track and rebuilding it was unecessary. I argued for simply dual trolleypole operation in the tunnel, moving one wire further to one side, and pantograph outside. And instead of lowering the track, simply accurately designing portable lightweight concrete risers moved into the tunnel over a weekend to raise the platfrom level. Would have saved several million but nobody listened.
daveklepper wrote: I had argued strenuously that lower the track and rebuilding it was unecessary. I argued for simply dual trolleypole operation in the tunnel, moving one wire further to one side, and pantograph outside. And instead of lowering the track, simply accurately designing portable lightweight concrete risers moved into the tunnel over a weekend to raise the platfrom level. Would have saved several million but nobody listened.
What's the problem with Seattle's approach? Isn't it the same as what riverboats frequently do when they have clearance issues? They don't raise the bridge, they lower the water.
But seriously, how did you conduct your argument? Was it just on railfan forums, or did you contact the Seattle transit authorities? Does anybody have info on what Seatlle's justification was for lowering the track instead of just fixing the platforms? Bear in mind that raising the platforms also has an impact on stairs, escalators and elevators, but I can't imagine how that's more expensive than lowering the track.
Also I'm assuming that they lowered the track only in the station platform areas, not in the entire tunnel. You've already mentioned that they had to do trackwork anyway because of electrical issues, I betcha their argument was that they would have had to close the tunnel anyway for that.
The consultants would not listen to outsiders nor consider all past practice of 120 years of streetcar history. They simply wanted light rail design to be similar to the other projects where they were consultants. The track did not have to be rebuilt if they used the Havana - Cincinnati dual wire approach in the tunnel. They had their minds made up before they even began the project. Never received any answer that addressed my questions. They never costed alternative approaches, only what they had used on other projects. Cookie-cutter consultants.
Obviously, desiging the individual portable risers to bring in to each station platform would have required quite a bit of computer-aided engineering effort, and ditto reprogramming escalators and elevators. And standard light rail cars today do not come with dual trolley poles.
A lot of government funded projects are like that. A lot of Acela's mistakes, the original Amtrak diesels, a lot of rail-related planning isn't any better. On the other hand, I think that original Amfleet and Superliner designs were amazingly good for their times and circumstances. PATCO in Philly and the M-1's for the LIRR and Metro North. The River Line. Both Denver and Salt Lake City light rail.
I am happy that Jerusalem is getting light rail. I am very unhappy that the cost per mile is twice what Canal Street New Orleans required with less attention to the latest research on how to reduce noise, vibration, and wear. And twice the turmoil in temporary disruption of downtown civic life. Use of girder rail instead of t-rail on straight PRW, pavement with individual paving blocks over concrete base, lack of continuous support of the rail, I could continue. Downtown Jerusalem should have had prefabricated track and roadbed panels lowered into precisely done excavations, not the tearing up of all of 3/4 (three lanes of four) of the city's main street (Jaffa Road) for what seems like a two-year period, and with only limited access to remaining very narrow sidewalks. Of course the merchants are protesting and filing law suites and so forth. All could have been avoided with intelligent design.
Yes, at one point the same consultants were used as in Seattle.
Yet another approach (which can be limited by overhead clearances) is to have the positive wire several inches lower than the negative. The trolley buses would have no problem with this, since the poles are generally independent, and the pantagraphs are held away from the negative wire by a few inches. This would be fine in the tunnels but probably not in the open where wire supports are further apart, and care would be required in the engineering to allow crossovers of the rail vehicles within the tunnels. I don't know what Seattle's trolley bus overhead voltage is, either, but with their light rail going in at 1500 VDC, that may play into the equation.
Commenting on another response: I doubt the stated reason for rebuilding the track (telephone interference), although that may have been an excuse given officially. I understand there were two problems: 1)- Rail to earth insulation was considered inadequate and there was concern over possible damage to underground infrastructure in the form of electrolysis due to leakage currents; and: 2)- the crossovers for short turns were located within the stations and between platforms rather than outside the stations beyond the ends of the platforms. Short-turning equipment would have been hampered by the body swing with respect to platform clearances and in the middle of a station is not the place to be switching cars from track to track where they would then have to reverse back into the platform to swap passengers. The engineers who designed that fiasco should have been decertified and had their licenses lifted.
Regards: Tom Fairbairn
No one told me about the crossovers, and they were not in the photos of the stations sent me. I agree such crossovers could not be used. But this still is only an excuse for tearing up the track, they could have simply not used the crossovers and installed new ones where operations suggested they could be used. And you solved all the current leakage problems with your idea (better than mine, involving just one pantograph and one trolley pole on each car). Note that in implementing your idea, there would be no reason with a suitably designed insulated car body (like all trolleybuses) why in the tunnel the pantograph could handle the negative side and the trolley pole and higher wire the positive. That way pole-dewirement would not leave the electrical equpment all at high voltage.
Again, creative engineering would have saved construction costs, and the tunnel would have been closed just for a seccession of weekends and not for a whole two years.
paulsafety wrote: Can't speak to Seattle's operation, but this video shows a European mixed use tunnel with both LRV (pantograph to single contact wire) and trolleybus with double wires held far to one side of the tunnel (where the pantograph wouldn't likely reach).The initial part of the video shows the dual use, the middle of the video shows better detail in a lighted station where you can see the trolleybus poles at an extreme angle.http://www.youtube.com/watch?v=d1EQkObn55IPaul F.
Very interesting and informative. Is that system in a German-speaking country?
Kerb seems to be a borough of Essen. Essen is a town in Western Germany, in the heavily industrialized Ruhr-Area.
Note the trolley-bus: it has doors on it's left side to be able to serve the island-platform (and of course on the right side). In Continental Europe, most buses have doors only on the right side. It must be a modified or specially designed car.
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