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Old 02-12-2015, 10:40 PM
 
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Quote:
Originally Posted by Malloric View Post
Like I said.

I wear in-canal headphones on BART because BART is annoyingly loud. It's far from unbearable. Also I work on BART and it's much easier to concentrate when the screeching is reduced significantly in volume.
Can't harm your hearing or make you deaf? Yet the article you just posted is titled

Mass transit noise may threaten passengers' hearing | Reuters

Gee I wonder what that means. Are they being too dramatic?
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Old 02-13-2015, 11:37 AM
 
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Quote:
Originally Posted by cisco kid View Post
For me the worst thing is the noise and ride quality. BRT may look a bit like light rail but it still
has the same noise and teeth-rattling ride characteristics because underneath the new skin and facelift its still a bus.
Proper roadway construction of a BRT lane can eliminate much of the shaking, while hybrid buses are significantly quieter than their straight-diesel cousins, and electric buses quieter still, and the remaining noise is the result of aerodynamics--the wooshing is namely of air rushing out of the way of the tires--which can be dealt with with proper aero design, like air guides and louvers.
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Old 02-13-2015, 11:42 AM
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Location: Long Island / NYC
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There's a larger difference between grade separation and non grade separation rather than just bus vs technology. I think focusing on the first contrast would be more productive.
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Old 02-13-2015, 05:44 PM
 
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Quote:
Originally Posted by darkeconomist View Post
Proper roadway construction of a BRT lane can eliminate much of the shaking, while hybrid buses are significantly quieter than their straight-diesel cousins, and electric buses quieter still, and the remaining noise is the result of aerodynamics--the wooshing is namely of air rushing out of the way of the tires--which can be dealt with with proper aero design, like air guides and louvers.
The BRT buses in LA have all of those improvements. They are hybrid electric buses with a sleek aerodynamic design. But there is no noticeable improvement in noise and ride quality as the video shows. The Toyota Prius is a very quiet hybrid car so you would expect to see some improvement in that regard with hybrid buses but you don't. Hybrid technology works well on small passenger vehicles but doesn't seem to be very effective when it is scaled up to something much larger like a city bus.
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Old 02-15-2015, 03:07 PM
 
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Quote:
Originally Posted by cisco kid View Post
The BRT buses in LA have all of those improvements. They are hybrid electric buses with a sleek aerodynamic design. But there is no noticeable improvement in noise and ride quality as the video shows. The Toyota Prius is a very quiet hybrid car so you would expect to see some improvement in that regard with hybrid buses but you don't. Hybrid technology works well on small passenger vehicles but doesn't seem to be very effective when it is scaled up to something much larger like a city bus.
I didn't bother to sit through the full video, but I didn't see any data comparing apples-to-apples dB levels. I can't assume the audio fidelity is 100%. But it does seem loud. So, some thoughts: the pavement wasn't autobahn smooth, given the shaking; that was a diesel engine running, given the sound, not the quiet, high-pitched whine of electric motors; the aero setup fore of the tires probably isn't amazing, as a proper setup can largely eliminate tire roar/woosh but requires extensive and expensive modeling. That said, if it runs on asphalt and/or above 45, you can never fully abate the tire noise.
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Old 02-15-2015, 05:54 PM
 
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Quote:
Originally Posted by darkeconomist View Post
the pavement wasn't autobahn smooth, given the shaking;
Do you understand how BRT works? The pavement was brand new at the time the video was made
and the new road built exclusively for the BRT in its own right of way. No other traffic is allowed on it.

Quote:
Originally Posted by darkeconomist View Post
that was a diesel engine running, given the sound,
The primary engine in a hybrid bus is the diesel or CNG engine. The electric motor only kicks in below
10 mph to help move the bus from a stop. But above 10 mph the bus moves on 100% diesel power.
That's why its just as loud as a regular diesel bus. The Orange Line is a CNG hybrid
not a diesel but CNG has no noise advantages over diesel. They are the same kind of engine
the only difference is the type of fuel used (diesel or compressed natural gas).

Quote:
Originally Posted by darkeconomist View Post
not the quiet, high-pitched whine of electric motors
A well designed electric motor should be virtually silent, not have a high pitch whine to it
which would make it noisy and as annoying as a regular combustion engine.


Quote:
Originally Posted by darkeconomist View Post
the aero setup fore of the tires probably isn't amazing, as a proper setup can largely eliminate tire
roar/woosh but requires extensive and expensive modeling. That said, if it runs on asphalt and/or above 45,
you can never fully abate the tire noise.
What is this mumbo jumbo? Tire noise is always going to be there it cannot be eliminated lmao.
Clearly you have never been on a hybrid bus before because you make so many false assumptions about it.
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Old 02-16-2015, 06:11 PM
 
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Even if the bus has a dedicated lane, it's useless if they don't plow it in winter.
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Old 02-17-2015, 11:43 AM
 
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Quote:
Originally Posted by cisco kid View Post
Do you understand how BRT works? The pavement was brand new at the time the video was made
and the new road built exclusively for the BRT in its own right of way. No other traffic is allowed on it.



The primary engine in a hybrid bus is the diesel or CNG engine. The electric motor only kicks in below
10 mph to help move the bus from a stop. But above 10 mph the bus moves on 100% diesel power.
That's why its just as loud as a regular diesel bus. The Orange Line is a CNG hybrid
not a diesel but CNG has no noise advantages over diesel. They are the same kind of engine
the only difference is the type of fuel used (diesel or compressed natural gas).



A well designed electric motor should be virtually silent, not have a high pitch whine to it
which would make it noisy and as annoying as a regular combustion engine.




What is this mumbo jumbo? Tire noise is always going to be there it cannot be eliminated lmao.
Clearly you have never been on a hybrid bus before because you make so many false assumptions about it.
I probably have a deeper and broader understanding of engineering than you do, given your responses and my background. You clearly have little understanding of aerodynamics, else you wouldn't have made a dismissive wisecrack about tire noise. You didn't seem to read what I said about the bus' shaking and the smoothness of the roadway, as I was talking about something that is unrelated to who uses that roadway and largely to do with how flat that roadway is. The high pitch of an electric motor does not imply volume intensity, as something can have a very high pitch but be barely audible, such as a mosquito's wings buzzing.
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Old 02-17-2015, 01:16 PM
 
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After some thought, I think you don't fully appreciate what engineering has to offer but I ran past the limit for post edits.

You show a lack of understanding of aerodynamics, else you wouldn't have made a dismissive wisecrack about tire noise. tire noise can be largely eliminated, as it is the sound of air being forced out of the way of the tire. Using aerodynamic winglets can smoothly redirect air out from in front of the tire. It cannot be completely eliminated, in part because asphalt is what it is and has lots of pockets for air.

You didn't seem to read what I said about the bus' shaking and the smoothness of the roadway, as I was talking about something that is unrelated to who uses that roadway and largely has to do with how uniformly flat that roadway is. Part of the noise of a shaking bus also has to do with the construction of that bus and the amount of sound deadening material is built in to it.

The high pitch of an electric motor does not imply volume intensity, as something can have a very high pitch but be barely audible, such as a mosquito's wings buzzing. A Prius in a parking lot, for instance, isn't making much noise, but the noise of the motors is a high whine.
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Old 02-18-2015, 08:29 AM
 
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Are you an engineer or a comedian? It doesn't matter what you do to the tires the engine and transmission
are the primary source of the vibration and noise not the tires. The pavement isn't old and riddled with potholes as
you claim it was purpose-built new for the BRT. Your "argument" is based on so many incorrect assumptions it
hardly deserves a reply.
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