ICTS noise
Maury Markowitz
mover articles on the Wikipedia, and I'm working on the ICTS/ART
article right now.
One question that has come up is the noise issue. When originally
proposed, the system was supposed to be very quiet - this was a major
design criterion. However, the system is widely commented on as being
fairly noisy. What is this noise?
Several newspaper articles from the era when the RT was installed
refer to problems with the wheels being rubbed flat by over-
application of braking. I was under the impression that most of the
braking was handled by the LIM.
Another article talks about Bombardier employees riding the RT trying
to figure out what was causing the problem. That's it.
Does anyone have some information on these issues or might point me in
the right direction?
Maury
Richard Gronning
I've been involved with PRT through Citizens for PRT since '94. I've
listened to Dr Ed Anderson expound on PRT for many years. I went to
Uppsala to see the Vectus system. Maybe I can answer some of your
questions.
Maury Markowitz wrote:
> When originally
> proposed, the system was supposed to be very quiet - this was a major
> design criterion. However, the system is widely commented on as being
> fairly noisy. What is this noise?
>
Which system? There are only two running and both for tests; 1) Vectus,
2) ULTra. Vectus makes as much noise as a fat-tired mountain bike. I
haven't seen the ULTra system, but I would bet that it's quiet. The 60'
of Taxi 2000 makes practically no noise, but it is only going at about
10 mph max. I wonder which system they're talking about.(?) Morgantown?
To begin with, Morgantown is technically a GRT. I've never heard that
it's particularly noisy, but I can ask people who would know. Who told
you this about which system?
> Several newspaper articles from the era when the RT was installed
> refer to problems with the wheels being rubbed flat by over-
> application of braking. I was under the impression that most of the
> braking was handled by the LIM.
>
LIMs were suggested by Ed Anderson, but 2Getthere and ULTra use
conventional rotary electric motors as far as I know. These systems
would have some sort of conventional braking, but I wonder what they're
talking about. Who said this for which system? They're all different.
> Another article talks about Bombardier employees riding the RT trying
> to figure out what was causing the problem. That's it.
>
Bombardier has no interest in PRT as far as I know. They're not involved
at all. Where did you get this information?
What are you referring to by, "RT?"
Dick
eph
http://en.wikipedia.org/wiki/Scarborough_RT_%28TTC%29
F.
Marsden Burger
Maury,
Some thoughts on both of your ICTS questions.
I was responsible for the marketing of this technology for the United States from 1981 until 1985 when the installation of the Vancouver, Toronto and Detroit applications were underway; later I was the operations manager for the Detroit People Mover, and left that position in 1996.
First the snow issue
The ICTS vehicle in the past had a small "cow catcher" at the front of the linear motor - I would expect that they still do.
This v-shaped piece of heavy metal simply met ice buildups on the reaction rail and shattered or sheared it away - the mass of the vehicle was too great for the resistance of the ice built up on an aluminum sheet that served as the upper element of the reaction rail.
The problem that you describe, would be the build up of ice under the motor that would eventually lead to the motor encountering the ice. At that point, if I follow your scenario, the ice would have an impact in some fashion on the vehicle operation. From the experiences at the three installations and the Kingston, Ontario test facility, the contact at this point resulted in the ice simply shattering. If one were to assume that over time the reaction rail were to oxidize to a greater extent, and the adhesion of the ice to this weathered surface would not allow it to shatter as it had in the past, then one would expect that the ice would either shear, or start to force the vehicle to rise. But the rising of the vehicles would assume that the force of the downward pressure on the reaction rails of the motors plow blade would not be sufficient to cause the ice to sheer, and that eventually the vehicle would be raised to the point where the vehicle would de-rail - which could be expected long before a multiple train set with two motors per car would lose power through the expanded motor air gap.
The quote that was used regarding my "odd" nature issue of the reaction rail was not addressing the issues you describe, but rather the issue that “any” snow or ice covering would cause a linear motor system to shut down or have operating problems. Something that I have not seen, or been aware of from my experience in this field - does not mean that strange things can not be the case in some situations, just that I am not aware of it. Here again were my full comments:
"This sounds very odd. From the test track in Kingston, to the operations in Vancouver and Detroit, I have not heard of this problem. The ICTS vehicle simply knocks the ice build up off the reaction rail. Problems with power pick ups and the packing of snow under the vehicles have been problems in winter - as they can be with any rail system, but the existence of snow on the reaction rail causing the system to shut down has not been something that I have encountered on any ICTS system application or any of the linear powered system that I have been involved with - ICTS, Transrapid, Cabintaxi, or M-Bahn."
The Scarborough line in Toronto has been subject to snow problems, but a quick phone call to those responsible for maintenance support to the Scarborough line indicate that the problem that you describe, has not been an issue. The Scarborough line problems come from many things, but the basic issue is that the line is subject to drifts too much for any vehicle system to handle. Once a vehicle encounters snow of the level that causes it to pack under the vehicle and lifts the vehicle, no system can be expected to operate, and the standard rail systems are more susceptible to these conditions than linear powered systems. Generally the problem is even simpler, the power rails, and their heaters, are overcome by ice build up and the vehicle loses power. Weatherization is the most difficult thing to address of all of the issues that go into transit system design. What water will do, and when it will do it, is usually only finally established on a one-to-one test facility.
What was shown on the Kingston test track was that an ICTS vehicle, from a standing start, could push its way through a six foot deep snow drift up a six percent grade. No conventional subway vehicle in the world can do that. That is only one aspect of a linear motor powered system. With this capability, the efforts to keep Scarborough project cost low could have easily led to accepting alignment situations that allowed drifting greater than conventional transit, because the system can handle snow problems better than conventional transit – just not all the levels of snow problems – maybe they over estimated how good the system was going to be. It just means that when you go from concept to installation, you are best served by having a lot of testing behind you.
Noise Issues
The ICTS utilizes the steer-able truck with the intent to reduce the noise in urban areas, while allowing the system to be more flexible for system integration than standard subway style transit. It is designed to do sharper curves at speed, and smaller curve radii than any conventional subway would ever do. This utilizes and requires a wheel profile and the track profile ground to the proper relationships, know as a worn wheel profile. What the ‘worn wheel’ profile does is allow the wheel to maintain one contact point between the wheel and rail and to allow the wheel to “ride-up” a bit on the rail when the system goes into a curve. As the wheel goes into the curve, there is a pressure that is created and that pressure is transmitted through a steering link back into the undercarriage and forces the final “steering” of the axel. By the axel steering in the curve, it keeps the optimum wheel to rail relationship that keeps the noise the lowest.
The goal here is to provide a low noise system that can have a lower cost of installation while having still high carrying capacity, a balance between more flexible routing (lower cost) and still high service levels.
To quote my favorite phrase, there is nothing more effective than an undeveloped transit system. It is going to do everything perfect, and only when you actually start getting to the real world, and finally to the “real world” do you start to realize that what you hoped for has potential limitations that one might not have calculated.
I have little doubt today that the ICTS systems, and the follow-on versions, are the quietest steel wheel systems in the world – that can do the curves that they can do, and when the proper maintenance is kept up. The ICTS system at its worst is dramatically quieter than a conventional subway at its worst. However, a subway system is laid out to more demanding requirements, because if they are not, the noise will be excruciating. The rail noise from a standard rail comes from the flange, used for guidance, contacting the inside of the rail while the rolling portion of the rail is riding on the surface of the rail. This creates a dual contact situation where the second contact point, the flange at a longer radius from the center of the wheel, is scraping up the inside of the rail at a faster speed than the contact point on the top of the rail. In subway operation you generally do not hear this, as the runs are straighter than what was hoped for in an ICTS system – remember, lower cost more flexible installation, not requiring as much tunneling or condemnation.
Now you add in some more imponderables at Scarborough, the addition of drivers to an automated system that was never meant to have them, but were forced as part of the political acceptance of the project. Now the automated system that was supposed to be computer controlled with blended braking has instead a driver who has the option to manually break and the problems of flats – wheels that go into a grinding slide – becomes magnified by the smaller diameter wheels, 18”, that are manageable under computer control, and meant to provide a smaller tunnel cross-section than conventional transit (smaller tunnel\lower cost as truly seen in the double decking of the Vancouver tunnel.) Now you take in the fact that the papers you are referring to were from a time frame where the rubber is just starting to hit the road (or more correctly, the steel is hitting the steel) and the new drivers do not really know the system and the 18” wheels slide a lot easier than what they were use to.
Next you add the reality that maintenance is often preformed more when “needed” than preventative, and when the profiles of the wheels and the rail start to wear with the noise relationships getting further from the optimum, when do you do the maintenance to bring the noise back into original spec…??? You have a budget that is short, and you have a pressure to keep the system moving, and the noise is no where near what a bad conventional system is - do you spend the time and money to keep the system in spec, or do you go until people start to complain..??? The best of technical intentions start to meet real world reality. “However, the system is widely commented on as being fairly noisy. What is this noise?”
What that noise is, is the noise of an excellent steel wheel steel rail transit system that was not stewarded into its Toronto installation by the same loving hands that created it. A very classical case where the outside observer will fault the technology as if “it” is the problem and the hobby technologist is sure that they could have done it better, where in reality, the real world is full of all kinds of imponderables.
Best wishes,
Marsden
Happily go into more detail if needed during your call.