^^^ Sounds like a job for Studio Gang. I've seen then use plexiglass in innovative ways in many concept projects. Perhaps, if angled properly, some kind of transparent barrier could be made to be relatively self-cleaning and provide the necessary debris/oil drop protection over walk ways.

The flap over the UP reconstruction project revealed pretty clearly that the modern standard is a ballasted bridge rather than a direct fixation, since a ballasted bridge allows the continuously-welded rail to continue without a break, whereas the direct-fixation bridge requires an expansion joint at each end.

Maybe that doesn't matter in a railyard setting, where there will be plenty of jointed track anyway.

There are plenty of European examples of innovative rail viaducts, but only in an American (or possibly Chinese) city would a massive railyard get built in a residential neighborhood, so this is a pretty unique design problem.

Your proposal for I-beams beneath each rail creates a big clearance problem. The clearance between rail and road is already so low that they had to use a through truss on the existing overpasses. I wouldn't be surprised if the construction depth already is less than 12 inches. Plus, a 12-inch depth wouldn't be able to span very far, so you'd need frequent supports - possibly even narrowing the roadway.

^ From aerial photos the current Garfield viaducts don't look like through trusses (assuming what Google Images displays as through trusses is correct).

There would be so much steel in building 20 +/- such through trusses that you'd think the money could be better spent on depressing Garfield slightly. Or, maybe instead elevating this (soon-to-be center) part of the yard could be compatible with a hump or gravity yard scheme (which needs only like 1 track at the center), where the center point is at a higher elevation (based on my very slight understanding of such things).

http://i51.tinypic.com/14ax2qf.png
Bing Maps

See the steel members sticking up on both sides of the tracks above the rail height? That makes them through-trusses, though they're quite shallow compared to what you might be picturing crossing a river.

I guess my thought was that if you were building a big new yard and crossing, it would be easy to elevate it an additional foot, or to depress the boulevard that much. By dividing it into three short segments, the girders could be under 40 feet, with less depth and less concern about torsion. Some combination of glass or polycarbonate just underneath could take care of dripping oil or debris. But I'd love to hear other ideas that don't rely on wishful thinking (this won't be a hump yard).

There was a time when the various park districts demanded "decorative" overpasses from railroad (and L) companies. That usually meant a little wrought iron or decorative concrete work. Here's the UP-N at Pratt:

http://farm6.static.flickr.com/5061/...96780e9c8a.jpg

Photo by Robert Powers from his blog A Chicago Sojourn

I've always thought the various under-bridge shield structures along the Riverwalk were excellently done. There isn't as much clearance here, of course, but you could look to those as a starting point.

You really only need protection for the sidewalks and maybe the boulevard median, although I'd love to see the median under the overpass planted up with shade-tolerant plants. You could also do what the IC did at the Midway, namely to put solid infill under the median span and create a terminus/focal point for the greenspace. On the Midway, the focal point is the Masaryk Monument.

http://img838.imageshack.us/img838/2964/masaryk.jpg

I can't wait for Clark and division to be cleaned. I can't imagine what a good cleaning will do for it's appearance.
9-25
http://i592.photobucket.com/albums/t...N/789a1db5.jpg

I for one quite enjoy the post-apocalyptic condition of Clark/Divison. It has a certain charm.

Supposedly it was to be rebuilt by CDOT after Grand/State was finished. I think they may have raided those funds though to actually finish Grand/State...

As far as I know, most of the money for the subway-station renovations has come from CMAQ grants, so they can't "raid" the funds.

My guess is that the constant bickering in Washington has prevented the creation of a new transportation funding bill, and the stopgap funding put in place hasn't included any money for CMAQ.

Poking around a bit it seems CDOT paid for it by borrowing against a number of other projects that were given federal funds, including the Clark/Division rebuild.

Ha, Post apocalypse definitely fits Clark/division

Hmm, seems you're right.

I agree, and it's been that way for at least a couple decades.

If Reilly is going to attempt to hijack the Jewel site with their redevelopment plans, perhaps he could just get them to do something to help integrate with whatever the city has planned for that remodel. I know one of the original rejuvenation plans for Clark/Division included putting in an entrance at Lasalle, although I don't know if they're still considering that. It'd be nice if they did, though.

It's really too bad that the city hadn't just spec'd out all the remodels and had them ready to go so they could have captured more of the stimulus funding. It might be nice, too, if Rahm asked CDOT to come up with some better-looking tile options. The current standard isn't really one I think is worth maintaining just for consistency's sake.

Apparently I'm the only person who thinks Chicago's subway stations should be restored rather than remuddled. Chicago's subways stations had a handsome, though spare, WPA Moderne design. Curved gray Vitrolite walls led to stairways lined with "radio black" marble. Down on the platform, bright (for the time) fluorescent lights illuminated clear, open platforms. Signage used a modern sans-serif design created specifically for the system.

Now we're intent on wiping out all of this moderne design just because the stations need fresh paint and better lights, and replacing it with a third-rate imitation of the IRT.

You practically can't get that when you google "through truss" -- you always end up with what you might possibly refer to as a box truss river bridge. I suppose the term might have a different meaning (your meaning) in the urban context of road-rail viaducts as opposed to long spans.

I remember the stated reason for the recent rebuilding of the North Avenue bridge as a combination suspension and cable-stayed bridge was to minimize the thickness of the bridge deck, in order to maximize clearance underneath. Presumably just depressing Garfield for a few blocks would be far cheaper than building something practically Calatrava-esque for a simple railyard at the edge of an impoverished neighborhood, but maybe it indicates there could be configurations other than those relying on the brute force of chubby girders to deal with the Garfield issue.

Speaking of the North Avenue bridge, the recent advent of bright and inexpensive LED lighting would allow the city (or NS) to bathe the entire underside of the Garfield viaduct in light, hopefully addressing one of the main worries there.

Looks like they got some more money between 2007 and now and the rebuild is apparently funded, including an entrance and mezzanine at LaSalle. Completion by......2017 :rolleyes:

Fortunately the long awaited combination of loop stops over Wabash is also still slowly moving forward.

http://www.chicagotribune.com/classi...4960861.column

No, I completely agree with you. I'm liking the program Rahm is pushing with the renovations/clean up of 100 stations. Unfortunately it might have come too late to buy time for more than a handful of the old stations. It certainly has bought some time for the Logan Square station which is much much nicer looking now. In fact, it looks almost brand new with the exception of a few hack-job repairs where ill-matched and over sized brick was used to patch the walls. I really like the design of the Belmont and Logan Square stations and am glad they will be cleaned up back to their clean modernist appearance.

My one complaint is that there is no auxiliary entrance at Belmont which really hampers it's ability to serve the extremely dense areas north of Milwaukee/Diversey as well as they should be served (Spaulding Aux is the only entrance within reasonable distance of that area and it's practically a 5 min walk once you are on the long ass platform). Any idea if there are plans to build an auxiliary entrance at Wellington/Wisner and Kimball? I assume the station was designed with that as a future option. In any case they at least need to add another set of stairs on the West side of Kimball because the current station entrance is just not big enough to handle the amount of traffic Belmont Blue gets. I regularly find the platform there crowded to the point that it is almost dangerous during morning rush. There are huge numbers of people piling out of buses and onto the train.

The news about Clark/Division is very welcome. CTA is taking the opportunity to extend the platform by an additional 2 cars, and building an entirely new mezzanine at LaSalle will prevent the annoying disruptions to riders that occurred at Grand. Then, once LaSalle is mostly complete, the Clark entrance can be shut down completely for modernization. It's a really smart move, even if it does extend the construction timeline. 2017 is really not that far out.

I wonder, though, if the new mezzanine is meant to forestall discussions of a new Brown Line station at Division.

I'm less thrilled about the new station at Washington/Wells. The east stationhouse at Madison is an architectural gem, and the stationhouses at Randolph are the same kind of elegant early-Modern design as the subways. On the positive side, it seems like there will be lots of access points to the new station, so the consolidation shouldn't affect walking times too much.

Mr. D, I agree with you about the elegant minimalism of the State Street Subway, but I'm not sure it's something that can really be restored. Vitrolite is out of production, and modern glazed-block doesn't have the same opacity or razor-thin grout lines. The large painted surfaces don't look very good over time, either, because the original concrete pours of the tunnels have serious issues with waterproofing.

Especially in harsh situations like an underground cavern, architects really need to future-proof their designs (within reason) so that ongoing maintenance and replacement can occur. Unfortunately, the WPA Moderne designs were a creature of their time, and shoestring public-transit budgets don't allow for expensive preservation work.

I do, however, wish the new designs had something more to offer than tacky multi-colored mosaics. SOM really set the bar for underground facilities at Millennium Station - easily my favorite train station in the United States. The CTA architecture has gotten better, though - I like the dark-blue barrel vault in the mezzanine at Grand. It really helps to organize the space. The new interior at North/Clybourn is also fairly well-done and restrained. Also, they all seem to use the same long box-shaped lighting fixtures, so that if one is broken, it can be replaced easily.

The new mezzanine combined with 10 car Red Line trains would probably only work to service existing and near term demand. Many times people waiting for trains at Clark/Division are not able to board during rush since the cars are already full to the gills.

The Division Brown Line stop will have to be built as well, particularly when the Atrium Village redevelopment goes ahead and the redevelopment of the CHA land gathers steam in coming years.

10-car Red Line trains? I don't even see that as a possibility. North/Clybourn, Grand, Chicago, Harrison, and Roosevelt are not long enough for 10 cars (are they??) South of there, it should be fairly easy to add 2 car lengths to the Dan Ryan platforms, and the Loop stations are all one continuous platform anyway.

IIRC, most of the issues were on the north side not in the subway. Belmont and Fullerton were not long enough until their rebuild was done. Sheridan and I think a couple others are also not long enough or are on curves which can't accommodate longer trains. There also probably isn't enough rolling stock to cover longer trains on the present rush headways.