I'm not sure what you mean by "viaducts." Every place where the railroad crosses above a street is getting a new through-girder bridge to span the street.

I'm unclear on the rationale for the wider track centers, but I suspect it's a UP systemwide standard. So they're insisting on it here even though there are no curves where freight trains might meet and tilt due to speed, and even though it's unlikely they'll ever carry enormous windmills or pressure vessels through here on flatcars.

Does catenary require more spacing?

Mr Downtown, as far as carrying wide-load cargo, presumably they could just do it at nighttime and have all the clearance they want without worrying about passing trains?

The $64k question here is, spreading the tracks is largely meaningless unless ... they're going to do it all the way to Zion or Kenosha or wherever. So, are there plans, beyond the theoretical, to rebuild further dozens of miles?

Catenary would only require more spacing if you put the line poles between the tracks.

Day or night, it's absurd to ever again expect any freight operations along the Shore Line, at least south of Highland Park. The line into Ogilvie is a cul-de-sac. Any freight to or from Proviso moves via the New Line. That's what makes me think the UP is just saying "oh, there's no reason for it; it's just our rule." Same as they're doing with the C&EI down in Roseland.

"Viaducts" I mean the elevated hilly embankment that the tracks sit on. I don't know what that's called. Are they changing that part or just the tracks? I still don't quite understand why they are doing this for an 8 year inconvenience. It's hardly a temporary thing. I think they should wait for more money if they can't do it quicker with the resources they have. At that rate it would take 100 years for them to redo all the track to Milwaukee. I kind of like the old bridges. They look really cool with the old rivets, just need a paint job or something.

Are the bridges really in that bad a shape? What's really going on with this project? There's thousands of these bridges all over Chicago that look the same. If so why aren't they replacing more of them if it's a safety hazard. I still don't get it.

Of course there are capacity constraints elsewhere as well, but it's a shame the new viaducts aren't being built to allow for future (re-)installation of a third track.

The embankments are just fine. They're not retained like the Red/Purple Line is, and the weeds and trees prevent most erosion. They really don't need a whole lot of maintenance, and they're good pretty much forever, unless they begin to subside.

It's the bridges that need replacement, because they're decaying and because replacing the bridges en masse is the easiest way to add clearance to the roadways below.

Since Metra is switching to a through-deck girder design, the plate girder between the two tracks will stick up 5-6 feet, and it will be fairly wide. This may require an increase in the track spacing to make sure the girder doesn't intrude on the train's clearance envelope.

^ I think I understand what you mean though I'm not sure what a "plate" girder is. But more relevantly, is the upshot that they will build no viaducts having supporting columns between roadway lanes or between roadway and sidewalk?

Also, how do you know all this stuff ?

^I don't think there are currently any viaducts on this line with center columns (except the special situation at Lincoln/Addison). Can you think of one? As far as I can tell, the current bridges all are through-deck girders, so the track centers wouldn't need to change on that account. I would imagine that the new bridges will have slightly deeper girders on the sides and will span from abutment to abutment without the piers next to the sidewalk as you currently have at Leland.

Would love to see them do something to the Addison/Lincoln bridge to make it less overbearing. It's a hulking unattractive behemoth.
http://farm4.static.flickr.com/3403/...0a186d85_o.jpg

Paint would be a start, but that must be WAY tooo hard and expensive.http://forum.skyscraperpage.com/images/smilies/koko.gif

It looks like the bridges south of Montose already have girders that stick up higher and don't have column supports on the side walk. Perhaps, they are newer.

Irving Park and Clybourn have column supports in the middle of the street.

There is an interesting solution to this situation in Evanston at the 5-way intersection of Ridge, Green Bay, and Emerson: After trouble with graffiti, the sides of the giant viaduct were covered with fabric. Presumably it's a quasi-temporary solution, but it really was carried out rather well.

^ Good news here. However, after seeing what is planned near the 55th street stop (Food4Less, gas station) I am becoming less and less hopeful of any "transit oriented development" despite what these architectural planners are presenting at these "visioning sessions", as described in the article.

I would love something like this in Chicago

http://home.rebstech.com/wp-content/...do--renfro.jpg

http://newsblogs.chicagotribune.com/...-downtown.html

September 27, 2010

Daley hopes Asian investors will bet on high-speed rail to downtown

Share | Posted by Hal Dardick at 12:11 p.m.

Mayor Richard Daley returned from his trip to Asia convinced foreign investors might put up the money to pay for fast, high-end rail service from O’Hare International Airport to downtown.

“I think they are very interested — China, Korea, Japan, the Middle East — yes,” Daley said today when asked if business people he met in China and South Korea might fund the effort. “There are many, many interests. You have to have a high-speed train from the international airport downtown. What that would do is that would rebuild our commercial market and our hospitality industry.”

Before leaving on the trip, Daley said looking for rail financing for the effort was one reason he was headed overseas

....

Daley repeatedly noted that it took him seven minutes to get from the airport to near downtown in Shanghai. “Just think, it’s seven minutes, they can get almost to downtown,” he said. “Seven minutes. That is unbelievable.”

...

And how is NY's High Line like the active commuter railroad bridge at Addison & Lincoln?

Sounds like Daley has seen the light and will realize there is no way you can accomplish rapid high speed operations by a ridiculous passing system on the Blue Line. The airport train requires non-CTA ROW and Stansted Express style operations.

^ :multibow :thrasher:

That would be so incredible if Chicago were to achieve anything close to this

I believe that this bridge is slated to be replaced in the next 5 years. It's part of the ongoing UP-N bridge replacement project being discussed. In other words you won't see any paint.

The best we can hope for is proper zoning so that eventually something transit oriented can be built. At this point, there is not enough spending power in those communities to be able to dictate any kind of building form or land use standards.