[Streety McCarface]

One thing to note with tunnelling: You can work through the winter and work through the winter well.

One risk with elevating the line (or even building it at the surface) is that you only have a small window of about 6-8 months every year where you can actually build the columns and do station pours without spending insane amounts of money on curing practices (Soaker hoses, burlap, poly, heaters, inspections, rebar heating, 28-day break tests, etc). Concrete curing has standards that must be adhered to at the highest extent especially on public works projects.

However, when tunneling, using precast tunneling segments doesn't have this issue. They can be formed, cured, transported indoors to prevent all these additional costs, meaning you can still construct the guideway even through the winter. On top of that, there is no need for laying off huge amounts of your workforce, returning rental equipment (incurring costs there), realigning traffic control measures, purchasing additional traffic control equipment, paying your management/admin staff during less productive timeframs,

Building LRT at the surface really is not as cheap as people claim it is. Look at how the bids for Hurontario and Finch turned out: They're costing so much more than what people originally expected. There were some really hard lessons learned back on previous projects, and you unfortunately are never going to see an LRT built as cheap as iON in this province ever again.

 

[afransen]

Couldn't elevated guideway be constructed with mainly precast members lifted into place? And it is not that difficult to parallelize the footings for columns and station construction. With TBM, don't you have to wait for the bore to go through before you can build the station? The station gets mined out from around the tunnel?

You have to be kidding about not disrupting traffic, after what happened on Eglinton.

A line like this should be grade separately to avoid conflicts with surface traffic--it should go up (elevated), not down.

 

[Streety McCarface]

Couldn't elevated guideway be constructed with mainly precast members lifted into place? And it is not that difficult to parallelize the footings for columns and station construction. With TBM, don't you have to wait for the bore to go through before you can build the station? The station gets mined out from around the tunnel?

You have to be kidding about not disrupting traffic, after what happened on Eglinton.

A line like this should be grade separately to avoid conflicts with surface traffic--it should go up (elevated), not down.

The I-Beams/Gurders? Yes...but that's pretty much it, and those are far more difficult to transport, especially in the confined spaces of midtown. The station itself and the columns/caissons have to be formed on-site. Worst of all, the joints still require concrete to be formed properly. As someone who has experience scheduling this type of sh!t, it's not as simple as it sounds. When drilling, there's groundwater, boulders, artesian wells, bedrock/shale, unstable soil, contaminated soil, etc that can throw a column's location into wack at a moment's notice. Concrete scheduling really complicates things on top of that. If the weather throws you a curveball, that's additional costs. When everything is underground, you have a lot more control over the temperature, precipitation, public safety, etc. There are of course risks, but there are other risks that are mitigated.

With regards to the TBM breaking through, that depends on the station construction methodology, however, if it's cut and cover, the station has to be excavated first, so it doesn't usually conflict with scheduling. Even with guideways, they have to be built before station forming can occur.

As someone who lived through Waterloo, I can 100% guarantee that it was far worse there. In terms of traffic control, I was not referring to specific measures, I was referring to traffic shifts that are required due to winter configuration requirements.

I'm not saying the line shouldn't be elevated, I'm saying there are good engineering and construction reasons as to why it may not be elevated.

 

[ARG1]

The I-Beams/Gurders? Yes...but that's pretty much it, and those are far more difficult to transport, especially in the confined spaces of midtown. The station itself and the columns/caissons have to be formed on-site. Worst of all, the joints still require concrete to be formed properly. As someone who has experience scheduling this type of sh!t, it's not as simple as it sounds. When drilling, there's groundwater, boulders, artesian wells, bedrock/shale, unstable soil, contaminated soil, etc that can throw a column's location into wack at a moment's notice. Concrete scheduling really complicates things on top of that. If the weather throws you a curveball, that's additional costs. When everything is underground, you have a lot more control over the temperature, precipitation, public safety, etc. There are of course risks, but there are other risks that are mitigated.

With regards to the TBM breaking through, that depends on the station construction methodology, however, if it's cut and cover, the station has to be excavated first, so it doesn't usually conflict with scheduling. Even with guideways, they have to be built before station forming can occur.

As someone who lived through Waterloo, I can 100% guarantee that it was far worse there. In terms of traffic control, I was not referring to specific measures, I was referring to traffic shifts that are required due to winter configuration requirements.

I'm not saying the line shouldn't be elevated, I'm saying there are good engineering and construction reasons as to why it may not be elevated.

Glad to have an actual engineer pitch in on this.

 

[robmausser]

I cannot believe how stupid this project is. If I didn't hear it from the Premier's mouth himself, I'd think this proposal was out of a Beverton article or something. $510 Million / km!? It is so mindbogglingly dumb.

Literally 1.5 billion dollars could be saved if they didnt tunnel the section from Martin Grove to Renforth....

 

[afransen]

Glad to have an actual engineer pitch in on this.

Seems like he is defending the status quo: that Toronto is doing everything right building some of the worst value-for-money transit in the world. Sometimes tunneling is the best solution, but it should not be the preferred solution. There are engineering challenges in any project, you could make an at least as compelling list of reasons why tunneling presents engineering challenges. I have never heard the argument that tunneling is the fastest way to build transit--it's a new one for me.

 

[robmausser]

Seems like he is defending the status quo: that Toronto is doing everything right building some of the worst value-for-money transit in the world. Sometimes tunneling is the best solution, but it should not be the preferred solution. There are engineering challenges in any project, you could make an at least as compelling list of reasons why tunneling presents engineering challenges. I have never heard the argument that tunneling is the fastest way to build transit--it's a new one for me.

Its not only new, its wrong.

Tunneling is by far the slowest method to build transit. Period.

 

[JSF-1]

Its not only new, its wrong.

Tunneling is by far the slowest method to build transit. Period.

Not just tunnelling but deep bore tunnelling which is the slowest and most expensive type of tunnelling. We could probably save some money and time going with cut-and-cover but that's never happening.

 

[syn]

Seems like he is defending the status quo: that Toronto is doing everything right building some of the worst value-for-money transit in the world. Sometimes tunneling is the best solution, but it should not be the preferred solution. There are engineering challenges in any project, you could make an at least as compelling list of reasons why tunneling presents engineering challenges. I have never heard the argument that tunneling is the fastest way to build transit--it's a new one for me.

That's not an exaggeration either.

At least one of our transit projects is considered one of the worst ideas in the world.

Before anyone points out the age of the article, the same people who defend it now defended the previous plan too.

We are wasting billions of dollars and value engineering the one project that deserves a sensible investment (the OL).

How did we get so bad at this?

 

[kamira51]

Glad to have an actual engineer pitch in on this.

And people will still argue over it being tunneled.

 

[NY99]

you unfortunately are never going to see an LRT built as cheap as iON in this province ever again.

Why specifically is that? What is it that iON did to overcome the supposed difficulties of building surface transit you described in your comment? They clearly got far, far better value for money than we’re getting.

Why can’t we just mimic their best practices instead of building an insanely expensive tunnel in the middle of suburbia?

 

[slapped_chicken]

is it deep bored tunneling for the all the tunnels on the west extension? Seems funny that metrolinx wrote an article on the advantage of the Eglinton west median for construction without mentioning it is easier to cut-and-cover in that same median without much disruption (unlike in midtown, where even just digging station portals were messy). Not that I think this particular extension should be tunneled regardless of method, although I find it funny that it appears they'll be choosing the most expensive tunneling option as well lol. Anyways, whatever way you put it, tunneled transit will always be the most expensive *and* slowest option, and probably should be only built where reasonable. It isn't reasonable for this specific extension - much more important for the nearly-finished midtown part of Line 5 where streets are narrow and buildings aren't setback far from the street, but not this area.

We are wasting billions of dollars and value engineering the one project that deserves a sensible investment (the OL).

Aside from the deep deep sadness I feel about the Science Centre station interchange (they should pour more investment to bury that part of OL), OL seems pretty good. EW and SSE are quite wasteful and could use the same kind of value engineering that OL got, which I'd much rather than burying the OL just because 'it deserves to be buried underground'

 

[Johnny Au]

Not just tunnelling but deep bore tunnelling which is the slowest and most expensive type of tunnelling. We could probably save some money and time going with cut-and-cover but that's never happening.

After all, deep-bore tunnelling is deeply boring at best.

 

[daniel_kryz]

Aside from the deep deep sadness I feel about the Science Centre station interchange (they should pour more investment to bury that part of OL), OL seems pretty good. EW and SSE are quite wasteful and could use the same kind of value engineering that OL got, which I'd much rather than burying the OL just because 'it deserves to be buried underground'

Thank you for mentioning this! What boggles my mind is how many people want the Leslieville section to be buried, without even noticing the importance of the northernmost part of the line! The Don Mills/Eglinton intersection will have tons of new high-density development and yet everyone cares so much more about a few houses - instead of the negative effects of the OL in a neighbourhood with far more people.

 

[superelevation]

That describes politicians at virtually every level of government.

Transit expansion was best when the city was in charge.

IIRC PC provincial governments were in charge when substantial amounts of the subway was getting built. Sorry to say but several streetcars or tramways on massively long routes (which Transit City was) would barely be justifiable with European land use. Also worth pointing out that what were supposed to be affordable projects are actually still super expensive (see below).

Couldn't elevated guideway be constructed with mainly precast members lifted into place? And it is not that difficult to parallelize the footings for columns and station construction. With TBM, don't you have to wait for the bore to go through before you can build the station? The station gets mined out from around the tunnel?

You have to be kidding about not disrupting traffic, after what happened on Eglinton.

A line like this should be grade separately to avoid conflicts with surface traffic--it should go up (elevated), not down.

I mean they are doing this on the REM iirc

Literally 1.5 billion dollars could be saved if they didnt tunnel the section from Martin Grove to Renforth....

1.5 billion is sadly not much in terms of transit in Ontario these days, that doesn't even get you the Finch LRT, would a very short LRT be worth not grade separating our second North South Line? Probably not imo, especially when connecting the massive job centers near Pearson as well as to the Miss. Transitway.