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  #15041  
Old Posted Feb 24, 2020, 6:42 AM
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Quote:
Originally Posted by Mr Downtown View Post
^Or build a turnback someplace near Chinatown and quit wasting all those platform hours running trains back and forth through areas of the city with suburban densities.
They still need space to hold more trains.
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  #15042  
Old Posted Feb 24, 2020, 7:12 PM
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Originally Posted by emathias View Post
They still need space to hold more trains.
No, if you turned back certain trains at Chinatown you could run trains more frequently on the North Side without an overall increase in the number of trains.

However, if the Red Line ever upgrades to 10-car trains then CTA would need to lengthen yard tracks at Howard. The 95th Yard already has longer holding tracks.
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  #15043  
Old Posted Feb 24, 2020, 9:59 PM
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Seems like you could probably squeeze a low speed loop under the tracks through that parking lot on the north side of Archer without a lot of trouble. Sure speed would limit throughput but you're not going to turn the entire line there.
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  #15044  
Old Posted Feb 24, 2020, 10:43 PM
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You don't want a loop, just a crossover or tail track. To even wheel wear, CTA likes having a loop at one end of the line (Howard, in this case) and a crossover or tail track at the other.

If CTA used drop-back operator scheduling, you really wouldn't need anything but an automated crossover north of Chinatown Station. But there's a lot more latitude for recovering from timekeeping problems if you have a third track to use, as at UIC/Racine.
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  #15045  
Old Posted Feb 24, 2020, 10:48 PM
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Originally Posted by ardecila View Post
No, if you turned back certain trains at Chinatown you could run trains more frequently on the North Side without an overall increase in the number of trains.

However, if the Red Line ever upgrades to 10-car trains then CTA would need to lengthen yard tracks at Howard. The 95th Yard already has longer holding tracks.
I'm assume the upcoming station rebuilds for Lawrence, Argyle, Berwyn, and Bryn Mawr will not include platform lengthening to accommodate the potential for running 10 car trains in the future?
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  #15046  
Old Posted Feb 24, 2020, 11:08 PM
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Originally Posted by Mr Downtown View Post
You don't want a loop, just a crossover or tail track. To even wheel wear, CTA likes having a loop at one end of the line (Howard, in this case) and a crossover or tail track at the other.

If CTA used drop-back operator scheduling, you really wouldn't need anything but an automated crossover north of Chinatown Station. But there's a lot more latitude for recovering from timekeeping problems if you have a third track to use, as at UIC/Racine.
I don't think there is much room in the row south of the portal to add a center track like CTA has elsewhere to facilitate a turn backs unless they feel like doing some likely expensive bridge work.

Alternatively the 13th Street incline could be used.
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  #15047  
Old Posted Feb 24, 2020, 11:17 PM
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Originally Posted by ardecila View Post
No, if you turned back certain trains at Chinatown you could run trains more frequently on the North Side without an overall increase in the number of trains.

However, if the Red Line ever upgrades to 10-car trains then CTA would need to lengthen yard tracks at Howard. The 95th Yard already has longer holding tracks.
It's already running maximum number of cars between Howard and South. The CTA is already running some rush hour Red Line trains on the Green Line tracks south of Roosevelt. If they go to 10-car trains, which they will need to do if the RPM project and increased development along the Red Line north continue the ridership growth at even close to the projections.

Their current maximum trains per hour on the Red Line is 30, but I don't think they actually run a full 30 trains per hour, I think 24 is their maximum, but they have multiple hours with 10-15 trains. If they have 4 hours of trains every 5 minutes, on average. A trip from Howard to 9th takes almost exactly an hour, so in a 4-hour period any given rail car can provide 2 full round-trips. So if there are 12 runs per hour of 8-car trains then you need enough cars for two hours in each direction for at least an hour to get the system primed. 8*8*2=128 cars, minimum, to support that service. The CTA's RPM documents project a need possibly as high as 35 Red Line trains per hour in 2040. That seems optimistic to me, but if that level of demand were to come to be, it could be met with either 35 8-car trains or 28 10-car trains. The same graph shows a maximum of about 22 Red Line runs per hour currently (in 2020). 22*8=176 cars per hour, and because each full run takes 2 hours to support that level for at least 2 hours requires double that, or 352 cars. I don't know what the CTA's in-service levels are, but lets say they can manage 90% in-service rates at the Red Line yards. That means they need to be able to hold 392 cars across the Red Line yards to meet the current maximum levels of service.

If their 2040 levels of service really do require the equivalent of 35 runs of 8-car trains, then they would require room for 623 cars, an increase of 59%.

And that's assuming that the projected 35-car runs assumes 8-car trains. If ridership actually demanded 35 runs per hour of 10-car trains, it would require 778 cars, or over double the current maximum needed. Now, chances are the CTA will not require that many cars, but either way the point remains the same that the CTA will need a lot more cars to meet projected demand.

Plus, turning back south of Cermak doesn't save as much as you seem to think. It takes 63 minutes to get from Howard to 95th, but it takes 45 minutes to get just past Cermak, basically a savings of 25% of the time and so if you turned back half of the runs, you're only saving about 12.5% of the needed cars. Even with that, you're looking at projected yard space increases of 50-60% more by 2040. You can't gain that by only extended track lengths at Howard, even if the space existed at Howard (which is a big if - maybe you could take over Triangle Park, but that would be unpopular and might not even solve the problem), because with additional cars, you need additional repair bays, too, and move for car movement for assembly and breakdown.
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  #15048  
Old Posted Feb 24, 2020, 11:46 PM
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First, the planning documents for RPM are going to show a huge increase in ridership because they have to justify the multi-billion expense of rebuilding the line, pulling from a Federal funding source (New Starts and/or Core Capacity) that are meant to either provide totally new transit service or add extra capacity to overcrowded lines, respectively. The planning studies have to show ridership growth because the Feds haven't created a program explicitly for "rebuilding crumbling rail lines". While the numbers are not outright lies, let's say they are probably very cherry-picked. I'm sure the planning documents for the Green Line rebuild and the Pink Line rebuild showed similar projections of high growth, even though the last 2 decades have shown nothing but population loss on the South and West Sides.

Second, even if there is high growth requiring additional service, it's likely most of that growth will be on the North Side. I'm sure it's mathematically true that this growth can be accommodated by a corresponding decrease in service to the South Side... if you want more air on one side of a balloon, pinch the other side. Of course, this would only apply at peak, and my vague sense is that the South Side ridership is less strongly peaked than the North Side ridership. So reducing service on the south Red Line (from, say, 3-minute headways to 6-minute headways) would not necessarily cause a capacity issue.

Third, such a trade-off may not be easy to make. Even if the turnback was built tomorrow, I don't know if the Red Line's infrastructure could handle 30% more trains circulating on the north half of the line, from a power, signaling, operational or safety perspective. It might end up being more cost-effective to just go bananas lengthening all the platforms to 10-car operation.

Quote:
Originally Posted by OhioGuy View Post
I'm assume the upcoming station rebuilds for Lawrence, Argyle, Berwyn, and Bryn Mawr will not include platform lengthening to accommodate the potential for running 10 car trains in the future?
Supposedly they will include this. Howard and Wilson already did provide 10-car platforms, and Fullerton/Belmont are designed to be easily extended in the future. Loyola could probably also berth 10 car trains with minor modifications. The Belmont Flyover project will probably open up the ability to extend Addison's platforms as well.
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Last edited by ardecila; Feb 25, 2020 at 12:11 AM.
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  #15049  
Old Posted Feb 25, 2020, 4:12 PM
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I don't think there is much room in the row south of the portal to add a center track
Look at an aerial. There's a tremendous amount of vacant IDOT land on both sides of the Red Line from 18th all the way down to 24th.



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  #15050  
Old Posted Feb 25, 2020, 6:22 PM
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Originally Posted by Mr Downtown View Post
Look at an aerial. There's a tremendous amount of vacant IDOT land on both sides of the Red Line from 18th all the way down to 24th.



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Oh I'm sorry, it's almost like I didn't account for that possibility in the part of my post that you cut off. Yeah you can add a center track there to do turn backs for probably a few hundred million that the CTA doesn't have.
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  #15051  
Old Posted Feb 25, 2020, 6:54 PM
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Setting aside the existence of land, the grades may not work. I believe the Red Line is on a grade from the tunnel portal until just before the Cermak platform... a sloped grade is probably not ideal for train storage since the brakes would have to be engaged the whole time... if the slope is not a problem, then the obvious candidate for a layup track is the existing 13th St portal.

The cheapest place for a flat layup track might be in the Dan Ryan median... just get rid of the breakdown lane on either side and spread the tracks apart. You could even do this south of 35th so CTA can bring on extra trains for Sox games.
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  #15052  
Old Posted Feb 25, 2020, 7:01 PM
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Originally Posted by ardecila View Post
The cheapest place for a flat layup track might be in the Dan Ryan median... just get rid of the breakdown lane on either side and spread the tracks apart. You could even do this south of 35th so CTA can bring on extra trains for Sox games.
That's not happening.
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  #15053  
Old Posted Feb 25, 2020, 8:35 PM
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You'd put the new third track east of the existing Chinatown station, on cheap solid fill, with an adjacent platform. The old northbound track would now be a center turnback track. The current station is virtually level, and so would be the new track. The old Alley L between 16th and 18th is another good option, but it would mean half the North Side trains wouldn't serve The 78 or Chinatown.

Can this be paid for by CTA next year, with the rent money from a new Dunkin Donuts downstairs? No; but we're comparing it to an $2.3 billion nearly useless five-mile extension to a sewage treatment plant, which will also waste hundreds of platform hours every day.
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  #15054  
Old Posted Feb 25, 2020, 10:11 PM
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A major, costly (feels like 100-150M) project to increase north side Red Line frequency that doesn't extend benefits to the south side is likely to be a considerable political problem. Adding turn backs to the Blue Line doesn't really raises any eyebrows because it's cheap to simply do. This would be noticed.
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  #15055  
Old Posted Feb 26, 2020, 4:46 AM
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Jarrett Walker has a good analogy for this: the Fishing Pier Distribution Problem. How is it fair to put all the fishing piers in oceanfront neighborhoods that are mostly well-to-do, rather than distributing them equally among all neighborhoods?

Rail transit serves dense areas. The north lakefront is 30-40,000 persons per sq mile. Gresham, Chatham, West Pullman, Roseland are 8-10,000 persons per sq mile, with no demand for any additional units.
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  #15056  
Old Posted Feb 26, 2020, 10:59 AM
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Edit: missed some of the previous discussion and answered my own question
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  #15057  
Old Posted Feb 28, 2020, 1:18 PM
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Quote:
Originally Posted by Mr Downtown View Post
You'd put the new third track east of the existing Chinatown station, on cheap solid fill, with an adjacent platform. The old northbound track would now be a center turnback track. The current station is virtually level, and so would be the new track. The old Alley L between 16th and 18th is another good option, but it would mean half the North Side trains wouldn't serve The 78 or Chinatown.

Can this be paid for by CTA next year, with the rent money from a new Dunkin Donuts downstairs? No; but we're comparing it to an $2.3 billion nearly useless five-mile extension to a sewage treatment plant, which will also waste hundreds of platform hours every day.
Can we all be incredibly honest here:

A lot of the "support" for the Red Line extension seems to be always cloaked in some "equity" framework about providing service to "disinvested" South Side. As a casual observer, I haven't seen any numbers on why it is needed so much or potential ridership, at least from its vocal supporters. It's more of a "well this is GOOD because of its investment on the SOUTHSIDE."

I hear a lot of that type of mentality in school and from articles. However, the other day in my spatial theory class we were talking about built form is a reflection of culture, economics, technology, and values of a generation(think old Boston vs suburban strip mall). Then I started thinking about the "controversial" building going up on Milwaukee(I think) in Logan Square. Does the potential of displacing some lower-income people in 2020 trump the fact that it's net positive will be paying us back even in 100 years? I guess with that thinking you could also argue that a Red Line extension is worth it because it could be a catalyst for future positive development in the far future. However, the current want for the extension seems to be more of a political move and investing that money in other more dense areas will probably pay off more in 5 generations.
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  #15058  
Old Posted Feb 28, 2020, 2:37 PM
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^RLX isn't a bad corridor but it's not the best in the city of course. I'm not sure it's so much "equity" but "politics" that prioritizes it. As mentioned earlier, the red line needs a bigger yard and that community was promised the RLX many years ago. Improvement of the MED would be a much more cost efficient way to bring transit to that area but it doesn't solve the yard issue.

In other news, apparently the CTA is finally doing a real all-door boarding pilot on the J14 (and by extension, the bus I ride most often, the 192, which uses J14 buses): https://chi.streetsblog.org/2020/02/...rnizing-buses/

For the 192, which picks up a lot of people from only a few stops this will probably make a big difference. I imagine the J14 has the same property at least on southbound trips and probably on the limited-stop portion of the northbound (although I've only been on the J14 like once so I know how peaky northbound boarding is).
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  #15059  
Old Posted Feb 28, 2020, 7:29 PM
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Improvement of the MED would be a much more cost efficient way to bring transit to that area but it doesn't solve the yard issue.
Why let the tail wag the dog? If CTA needs more yard space, they should simply expand their yards.

Just a quick glance an an aerial image shows several ways in which the two Red Line yards at 95th and Howard could be expanded, at a small fraction of the cost of the RLE project.
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  #15060  
Old Posted Feb 28, 2020, 9:38 PM
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Honestly I don't know why the existing 57/94 diamond interchange can't accomodate a vastly larger yard. Look at a satellite, it would obviously take strong coordination with IDOT to replace some of the embankment sections with aerials or just a few cross-unders to allow expanded yards to the southwestern part of the right of way, but it seems imminantly doable.
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