Some Sound Transit light-rail screeches just won’t stop
Just to raise the sights a little, light rail, often promoted here as the solution to all our transit concerns, is proving far from problem free in Seattle. Noise is a serious issue – and they are working hard to do something about it.
Surface light rail does have impacts on its surroundings. Indeed, it would be foolish to think that any technology has no impacts at all. Wind farms look very good in comparison to off shore oil wells these days, but are still a threat to birds.
While I do not recall there being very many public outcries against the noise of our rapid transit, the one that bothers me as a reasonably frequent passenger is the squeal on the Canada Line as it winds its way around the granite outcrop underneath Queen Elizabeth Park. Initially I thought this might get better as the track was conditioned – or through a combination of wheel turning and rail grinding. I cannot say I have noticed any improvement. That did seem to work at some places in Seattle – but not all of them
Rail grinding last winter improved the sound on much of the line but loudness inexplicably increased near the river
They are also going to to try flange lubricators
Transit contractors installed lubrication machines to reduce screeching on curves. The biodegradable gel automatically is squirted on the rails, where wheels pick it up and spread it near Mount Baker Station. The lubrication is helping somewhat, and Gray said one lube point will be moved closer to the Beacon Hill Tunnel soon.
Since the squealing only occurs inside a tunnel there are no neighbours to annoy, and I suppose that users of the Canada Line are expected to simply tolerate it. It does not happen on SkyTrain since the trucks under the cars have steerable axles. I don’t think that is an option with conventional traction motors which tend to be hung on the axles on most electrical multiple unit trains. But I would also think that since the noise is created by metal grinding on metal that is must have cost implications in track and wheel wear too.
Stephen Rees's blog 
The Canada Line is overall a very smooth ride from my experience on various systems in Europe and North America, but that segment is one of the worst noises I’ve heard. I remember the BART from SFO to downtown San Fran having some really noisy sections. Both in tunnels which doesn’t help either.
Warren
June 7, 2010 at 12:58 pm
Portland’s MAX system uses a modern waterbath (sprinklers that turn on as the train approaches the curve) technique to reduce flange squeal on tight curvature.
zweisystem
June 7, 2010 at 1:00 pm
I remember there were noise complaints when SkyTrain opened and they continue to run trains slowly between Stadium and Main in order to keep park users and residents happy.
The QE Park section of Canada Line is particularly bad and I get to “enjoy” it twice a day. I’ve got to think all that noise indicates a lot of wear and tear on wheels and rails.
SkyTrain is generally quieter, but because it’s outside most of the time people tend to open windows so it can get pretty loud in the tunnel.
I’m happy that the bus route near my house uses mostly new Nova diesel and hybrid diesel buses. Even with the windows closed I can tell when one of the older Flyer low floor buses goes by.
David
June 7, 2010 at 2:51 pm
The TTC Subway in Toronto was/is awful at the turn south from St. George to Museum Station. The squeal there was high pitched and deafening depending on the particular train – many people put their hands over their ears..
Ron C
June 7, 2010 at 3:51 pm
The squealing sounds produced by wheels on the curves at Queen Elizabeth Park are the result of check rails installed at three or more points on each curve. There are check rails near the start, mid-point and end of each curve; these are visible through the train’s windshield.
Expect the noise to continue as long as those check rails are in place. It seems the operators consider the noise to be a reasonable trade-off against the risk of derailment at a tricky spot.
Melfort
June 7, 2010 at 4:24 pm
Another factor that helps in minimizing the squeal is to bank the track at the turns.
To save money they decided not to build the Canada Line with a bank at the turns around QE park.
Which you will probably notice a lot of turns along skytrain are banked. The ones that aren’t banked tend to squeal a lot more. One prime example is the turn on the west side of the Main st Station. Another is the one right by Broadway.
Paul C
June 7, 2010 at 7:17 pm
Thank you. I should have thought of that. It is also known as “cant” or “superelevation” and there is a discussion of that on
http://en.wikipedia.org/wiki/Cant_(road/rail)
Stephen Rees
June 7, 2010 at 7:22 pm
Thanks for the link. I didn’t know the actual term for it. The other big advantage to it and was mentioned in the link you provided. Not only can it reduce the squeal of the wheels. But it also allows a train to go around a curve at a higher speed.
Paul C
June 7, 2010 at 11:03 pm
I’ve noticed it also slows down for that curve much more than I notice it on skytrain, so yes, a cant would be really helpful. Too late for that, but anything to stop that awful squealing would make the ride a lot more comfortable. I really wasn’t expecting it when I first rode the train, as I never noticed it at all on skytrain.
Tessa
June 8, 2010 at 12:14 am
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re:place Magazine
June 8, 2010 at 9:52 am
@Tessa
I’ve noticed it on the old skytrain as well. Especially at Main st Station and Broadway Station. Although it doesn’t seem to be as bad. Which I think can be attributed to the fact that the trucks on the cars of the MKI and MKII trains are steerable as Stephen mentioned.
The sad fact for me is they didn’t put the cant in that area all to save a bit of $$$. Which on a project that is at least $2Billion is really stupid. How much more would have it really cost. To me it would be like having a house built, but then deciding to not install a door bell just to save some $$$.
Paul C
June 8, 2010 at 11:07 am
Canada Line also makes a lot of noise between Yaletown and VCC. I don’t think check rails can be blamed. When you look out the front window most of the corners are just the regular two running rails. If other steel was the cause of the noise you’d only hear it when the trucks crossed those points, but the screeching is continuous.
Canada Line was built with provision for a possible future station at 33rd so that may have played a part in keeping things as flat as possible. However, I don’t believe a station at 33rd will ever make sense.
There are 3 logical locations for future stations based on purely on spacing. 17th, 33rd and 57th.
17th is already zoned for 4 storey mixed use, but it was never identified as a possible station location.
33rd is beside the city’s second largest park where nothing can be built and it’s on the edge of a steep slope making it difficult to access from the west. Yet it was identified as a possible future station.
57th is the other location where a future station has been pencilled in. It has some existing high density housing which could mean more in the future.
David
June 8, 2010 at 11:45 am
@David
17th or any section in that area. Can never have a station in the future. The track is at an incline in that section. So unless you want to build a station with a massive slope and baby carriages rolling away. It will never be built.
That is why there is a short section between 49th and Marine that suddenly flattens out. That is where the future 57th station would be put in.
Paul C
June 8, 2010 at 12:05 pm
The cant of a rail line at curves has nothing to do with flange squeal, it has everything to do with passenger comfort; to prevent passengers being flung out of their seats on curves. It is the same reason why we have ’tilt’ trains, which tilt at curves to keep passengers in their seats on curves.
Trains remain on the rails by the principle of conicity. All train wheels are coned and being so designed, maintain an equilibrium when traveling on the rails including curves. In fact, the flange should not touch the rail at all.
Flange squeal does happen on tight curves and switches/turnouts/points. Flange squeal could be a problem of poorly laid or maintained track or poorly maintained trucks or bogies. Corrugations on the rail also cause noise and SkyTrain went through several years of rail grinding trying to cure noise issues.
The squeal on SkyTrain could be a problem with the self steering trucks, which when poorly maintained tend to ‘hunt’ or move back and forth causing squeal and noise, plus making it uncomfortable for passengers.
Most modern trains & tram’s trucks (bogies) do steer but unlike SkyTrain do not actively steer the other axle. I believe the ROTEM EMU trucks also steer, with the axles held in place with rubber-like ‘chevrons’, which permit the axle to steer on curves.
The on going noise problems on most transit systems can be traced to poor installation and/or poor maintenance of track.
As for stations on grades, the steepest tram stop in Sheffield is 9%, with metro’s stations can be placed on slight grades with no problems.
zweisystem
June 8, 2010 at 2:34 pm
@ Paul C
I know Cambie village can never have a station because it wasn’t planned for.
My point is that it makes more sense to plan for a station in a growing, mixed commercial/residential area than to plan for one in a location with poor accessibility and very limited development potential.
David
June 8, 2010 at 4:12 pm
“The cant of a rail line at curves has nothing to do with flange squeal”
basic physic eventually suggest otherwise (think a ball rolling down a gutter): you need to have a cant in order to avoid to rely on flange squeal, to keep you in the trajectory otherwise, which reason could have the train to turn?
but back to LRT (where typically cant is not an option)
I have noticed that European LRTs don’t rely on axle anymore, and seems to have independent wheel, allowing the outside one going faster than the inside one:
That eventually reduce friction problem in tight curve, hence noise:
LRT not relying that much on conicity (I have heard they have in fact cylindric wheel) have to rely on flange to keep them on track, but at this moment the outside wheel has more distance to run than the inside wheel in the curve…
at the end, the noise on the Canada line is amplified by the reverberation of the tunnel: Toronto St georges is also in this case, but the approach to Union station is far worse…
I had been surprised by the noise of the Canada line, and could have been quick to blame P3, but from David comment, it looks it is more the project definition with the very improbable 33th station forecast to blame in that case (which may be also justify this useless elbow).
voony
June 8, 2010 at 8:59 pm
^Good point about the curve and the future 33rd avenue station, voony.
If anything, once the old st vincent’s and RCMP lands are re-zoned and TOD built, we will see the movment with the 33rd AVe station. I wonder if this will happen before or after ProTrans’ concession ends, though.
mezzanine
June 8, 2010 at 9:14 pm
If a train or tram has to rely on the flange to keep it on the rail, it will soon derail. Streetcars, of course are not canted at curves, especially tight radius curves, for obvious reasons, but most LRT lines are canted on high speed sections.
Many low floor tram designs are axleless and use vertical motors to power wheel sets because an all low-floor tram (250mm to 350mm) above the railhead can’t use a conventional axle truck.
To restate, a cant on a rail curve is to mitigate centrifugal forces, when traveling at speed and has little to do with flange squeal. The lower the speed on a curve, the less cant that is needed.
Without a cant on a high speed curve, a train would derail, flange or no flange.
George Stephenson demonstrated the principal of conicity to a Parliamentary Committee in the 1820’s, by building a model which consisted of a sloping curved track and coned flangeless wheels on a small truck, which rolled down the curved grade without derailing.
zweisystem
June 8, 2010 at 9:57 pm
Mezz,
to the risk to be off topic, but since we are talking about 33rd avenue:
I will bring one principle of sustainable communities as worded by Patrick Condon:
“Create a linked system of natural areas and parks”
As you could know I could have some reservation on some of its principle, but certainly wholeheartedly agree with this one:
as such I believe the 33rd corridor, should be reserved for such from Granville to Fraser: Connecting Van dusen garden to the cemetery along Fraser (thru Riley park)
…hence don’t see a subway station at 33rd as a desirable from an urban form perspective (discounting the fact it will slowdown my commute from Richmond 😉
voony
June 8, 2010 at 10:51 pm
@Zwei.
While cant won’t eliminate all flange squeal. It does help to mitigated it by helping to keep the wheels more centralized on the track.
I do agree though that the main purpose of cant is to allow a train to traverse a corner at a higher speed without derailing.
“As for stations on grades, the steepest tram stop in Sheffield is 9%, with metro’s stations can be placed on slight grades with no problems”
I believe the maximum allowed grade for a station is 1-2%. There is no way we could have a track with a grade of 9%. The platform would never line up with the train. And a station platform with a grade of 9% would be suicide.
Paul C
June 9, 2010 at 2:25 am
I did say, “with metro’s stations can be placed on slight grades with no problems.” I would wager 1% to 2% grades are slight.
Again I reiterate, Sheffield’s steepest tramstop, with platform is on a 9% grade. I did not place it there!
I was told by a ‘track’ specialist some years ago that flanges touching the side of the rail was fraught with bad consequences, at speed. The lower the speed the less bad consequences. With simple trams or streetcars, flange squeals indicate locations of excessive track and wheel wear and can be mitigates with water-baths or track/wheel lubricants.
zweisystem
June 9, 2010 at 11:09 am