Originally Posted by MalcolmTucker (Post 7116256)

Well, the less dirt you have above a tunnel, the more structural strength has to be gained from the tunnel materials itself, not from adapting the ground to use as structure. Plus there would be codes on crossing underneath rivers - wouldn't want the tunnel daylighted during a flood event.

Originally Posted by sim (Post 7115767)

I'd go with Option B or Option D.

Option C is a non-starter. Option A would aid in replicating past mistakes - in that the travel time through the centre would reduce the lines diametrical efficacy, i.e. for trips going through the centre, not to the centre.

Although I'm for Option B or D, I predict and believe what will happen, assuming all the funding does come together, is that when actually looked at a bit closer, Option B will look a lot more challenging and would have actual costs that are much closer to those of D.

The large difference in costs appear to be because D would be bored and B would be cut & cover - otherwise the cost difference doesn't make sense to begin with.

While I don't doubt it can be technically done, I'd be curious as to how it is thought that the savings between the two methods can be realized, given the myriad of operational and logistical challenges presented by cut & cover.

So we are going to go under Macleod, go under CP, go under a parkade entrance, go under the current LRT line supposedly with, remove/relocate countless utilities, remove ~ 5 - 10 high value properties on a bluff and trench into something that will take some considerable stabilization, and disturb/disrupt businesses - some of which likely have disproportionate influence, all with cut and cover..? Or tunnel-jacking? The Evergreen Line jack (posted above) had considerably less constraints than any of the above would.

Well, good luck. Even if all that can directly save some of the $500 million, it may not be worth the headache and likely community opposition.

And that it needs to go 20 metres under the river in Option D, I'm sure can be reevaluated as well. Likely trying to stick to bedrock to avoid boring in very wet till, but if my limited understanding of tunnel methods and soil mechanics serves me correctly, there are methods to address this - freezing it for example.

Ultimately, I think the next step would be to take those two options and look at them in detail.

Originally Posted by MalcolmTucker (Post 7116109)

Staying underground means they don't need to find space for a tunnel portal. Not counting the land needed underground (whether sites not on the roadway sterilized from building, or land acquired to retain enough road lanes) for the portal approach, this tunnel to elevated section in Vancouver requires 180 meters.
http://i.imgur.com/oFtihKj.png

A tunnel portal where you are already planning to take part of the ROW for the LRT doesn't take any additional land.

Originally Posted by shogged (Post 7115337)

option c would be my first choice. I think the low floor aspect of the line would be better suited to an elevated design vs a subway. the first station under the hill in option D at 13 stories underground seems insane.

Originally Posted by RyLucky (Post 7115985)

I think an interesting side effect of the elevated option is that the +15 Network will be increasingly perceived as "public" space. Currently, it is a little uninviting to those who don't have business walking through downtown office towers. If an elevated train was made to inferface beautifully with the +15s.

Originally Posted by Nouvellecosse (Post 7116084)

After looking at the options and checking out the affected areas on street view, what I fail to understand is why they all involve a tunneled section on centre st before 20th ave. Why not have it elevated?? I mean, it's not like it's going to hurt the "ambiance" of the street or anything.

Out of the existing choices (as someone who's admittedly not a Calgary expert) I'd go with C.

Originally Posted by red_179 (Post 7116603)

I like Option C the best. I like that it elevates earlier on 10th Ave (1st St SE), than where the tunnel would begin (1st St SW). A few extra blocks not being at grade will be helpful for traffic.

Originally Posted by ssiguy (Post 7116338)

I'm probably dreaming in technicolour but............if they decide to go under the Bow then the tunnel will have to be very deep. Is it therefore possible that at roughly Stephen Ave they have the deep Green Line station that connects with a on top and shallower east/west tunnel for the other system lines?

Originally Posted by suburbia (Post 7116672)

Looks like my choice has some momentum here. I've been advocating for an elevated downtown section for a very long time now - from well before the options came out. My thought process had always included what RyLucky is now cluing into, which is that this will enhance the +15 network (while also not being so far away from the street as the burial option would take it). I'd bet the police would prefer the non-buried option also.

Originally Posted by RyLucky (Post 7117117)

I know proponents of option C will try to sell it as though it were the Loop in Chicago, but 2nd st is much narrower and concrete would likely be used instead of steel in Calgary. While Chicago has a lot of great things about to do in it, strolling under the elevated rail is anything but pleasant. Could there be a way to design around these problems? Maybe. If the prices are comparable, option B is probably preferable.

Originally Posted by PPAR (Post 7117167)

I have yet to walk under elevated rail in any city (thinking of experiences in Vancouver, Seattle and Chicago) without being uncomfortable with the surroundings. Elevated rail ruins streetscapes in my experience and would be a disaster in downtown Calgary where the street ambiance is improving but continues to be suboptimal.

Originally Posted by ClaytonA (Post 7117437)

Found this table in the publicly accessible January 2005 SELRT Future projections study of preliminary ridership estimates. It's dated now, but with Lynnwood, Ogden, and South Hill being appreciable, it's not as bad as the criticism that it needs to reach Douglasdale/McKenzie Town before significant ridership. Note that 1.25 million population was supposed to be reached in 2033, not 2016-7ish.

Originally Posted by ClaytonA (Post 7117437)

Found this table in the publicly accessible January 2005 SELRT Future projections study of preliminary ridership estimates. It's dated now, but with Lynnwood, Ogden, and South Hill being appreciable, it's not as bad as the criticism that it needs to reach Douglasdale/McKenzie Town before significant ridership. Note that 1.25 million population was supposed to be reached in 2033, not 2016-7ish.

Originally Posted by Wentworth (Post 7117573)

I can't see there being 5400 people living in the Lynnwood area. Maybe this study is so old that is based on the pre-evacuation population?

Originally Posted by MalcolmTucker (Post 7117630)

Maybe Lynnview had a larger park and ride lot in the 2005 study? Probably a transfer point for buses serving Foothills Industrial, and Erin Woods and Dover — it is a six bay bus loop sketched there.

Originally Posted by ClaytonA (Post 7117437)

Found this table in the publicly accessible January 2005 SELRT Future projections study of preliminary ridership estimates. It's dated now, but with Lynnwood, Ogden, and South Hill being appreciable, it's not as bad as the criticism that it needs to reach Douglasdale/McKenzie Town before significant ridership. Note that 1.25 million population was supposed to be reached in 2033, not 2016-7ish.

Originally Posted by nick.flood (Post 7116800)

Elevated would need to be +30, and while you'd have more use of the +15 to get up to it.

Originally Posted by ByeByeBaby (Post 7117757)

It's not as bad? It's worse. I dug up the 2005 platform counts by line. Only one of the 13 stops was even above average; 6 of the 10 lowest ridership stops are on the SE.

http://i.imgur.com/J3WQfTJl.png
Link for full size