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DH |
Elevated lines in Chicago are basically open deck plate girder bridges which do absolutely nothing to dampen noise, and in a way amplify it, because vibrations are transmitted almost directly from the vehicle to the structure. Modern elevated lines are much, much quieter.
There probably is some way to dampen noise somewhat. Some composite crosstie material that dampens vibrations better than wood. Or some thinner material that leaves extra room for a buffer between the ties and the girders. They say that the L is significantly over engineered, so even a solution that added quite a bit of weight might still work. Maybe something that closes the deck. You'd then have to worry about drainage though. So not sure what can be done. It would probably be expensive no matter what. |
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http://i155.photobucket.com/albums/s...f/P1030772.jpg Orange Line built along railroad right-of-ways, http://i155.photobucket.com/albums/s...030697.JPG.jpg http://i155.photobucket.com/albums/s...f/P1140913.jpg Rehab project rebuilding the Pink Line (former 1895 Metropolitan Douglas Park "L". DH |
The 18th street connection and much of the orange line are examples of more modern elevated structures with ballasted, closed decks and concrete noise walls. They are also much, much quieter than the Lake Street or Loop elevated tracks. They are more visually obtrusive too since light can't pass through the structure, but I'm pretty sure fixing the noise would be worth it. I wonder if the Lake Street or Loop elevated structures are strong enough to support a retrofit to those standards.
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I wonder what the effect would be if they put in dampening ties and added sound walls without going to the extreme weight of a ballasted deck. Would that provide maybe 60% of noise reduction at less than half the cost of a ballasted deck?
Part of the reason DLR structures seem lighter and less obtrusive is because they don't have a ballasted deck or sound walls. It's just a concrete box girder with tracks embedded in the top. |
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DH |
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DH |
^ And CTA's rolling stock looks puny compared to NYCTA or WMATA's 75'-long cars. It's all relative. But importantly, the short car length means DLR can make sharp turns in congested areas without having to tear down buildings. Maintenance yards can be more compact, etc. That could come in handy in a built-up area like downtown Chicago where underground construction is to be avoided.
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Its all a dream anyways....given the costs NYC's Second Subway is the last we'll ever see of such projects. DH |
Imagine how much property values in Uptown, Edgewater, or Loyola would shoot through the roof if the CTA actually had express trains on the north main red line.
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DH, it's not clear that CTA would play any rôle in the Connector project. It's still at such a preliminary-study stage that they haven't had any serious discussions with any operating agency, though they've been told that an actual transit agency will be required to talk with FTA.
I raised the question of incompatible rolling stock with the main consultant, who replied "I do not want to use existing 'L' car design with 19th century dimensions; want 10' car width if possible, much more efficient loading." |
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a) Fare that are possibly compatible with Metra, which will effect the ridership modeling and whatever farebox recovery that they maybe expecting. b) How the fare of this will effect CTA ridership will it actually relieve loading in part of the L that are going over capacity? Quote:
The CTA car dimensions are a base framework and in fact working off of that with a slight modification will make the cost of the work of the railcars cheaper and more likely that this can get off the ground. Or a set of articulated high loading floor light rail trains which are the same width of the CTA trains. SMH |
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No public meetings yet, and still some distance from one. At this point, it's just an idea being explored by the Chicago Central Area Committee
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*: Looking carefully while on Broadway, even the old viaduct has had some columns completely replaced (not yet available in Google streetview) with temporary new ones during the complicated construction project, so even the old viaduct is probably enjoying some sound dampening. The difference is nevertheless noticeable. In any case, because this is next to a station, I doubt it will be possible to make a comparison with trains running full speed. |
^ I live in the vicinity and I can vouch for this statement, since they replaced the old western most viaducts the noise level is unnoticeable for passing trains whereas before it use to be unbearable at times.
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New Green Line 'L' Station Planned At Damen and Lake, City Announces
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I'm glad they're adding this. I kinda wish they'd decided to do both this one and one at Madison/Pink. Damen is better because there is more existing residential nearby, but that sea of parking lots near Madison/Pink could easily become developments if there were a stop there. At some point the land value will be high enough that United Center can create multi-story parking garages adjacent to the Center and do some intensive development on the outer lots. |
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that CTA stop is badly needed there for UC. I always thought maybe they would do a giant pink line stop right where it crosses near the UC to the east I wish they would eminent domain a couple of those ridiculous parking lots |
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