[crs1026]

This might be common sense but I was really wondering...

Why don't the lrt trains have third rails? Wouldn't it make sense for lrt trains to use a third rail whenever they are in a tunnel? One of the things that increases cost for lrt underground is the need to build in clearance for the catenary no?

Third rail is great for heavier rail that is used throughout the length of the line, but adding pickup shoes to LRT vehicles that will run above ground for long stretches is not that practical. There are platform clearance issues created, and the risk of electrical contact with pedestrians is not acceptable.

There are certainly systems out there that use third rail for above ground lines, but that's not ideal for Toronto. We don't need memorial shrines all along the Jane-Humber flats just because another raccoon has contacted the third rail.

- Paul

 

[rbt]

It seems to me it would make so much sense to have trains that would transition from catenary to third rail the second they entered a tunnel retracting the pantograph and significantly shrinking the size of tunnel needed, surely the engineers at Alstom or Bombardier could figure that out?

3rd rail has a number of issues (mostly smoke/fire and evacuation challenges). Overhead fixed rail (see Queens Quay and Spadina tunnel portions) is preferred by a number of Metros around the world for new tunnelled lines; even entirely underground heavy-rail ones.

Eglinton's tunnelling costs were not noticeably more expensive, as a %age of the overall project, than Spadina's (adjust for start year).

 

[dowlingm]

Mixed catenary and 3rd rail also means more weight for the pickup shoes which is another thing which will need maintenance. Also, with low floor cars shoehorning more stuff in at wheel level is another PITA.

 

[Edward Skira]

Getting closer.

 

[hawc]

Are the machines tunnelling towards each other? What happens when they meet?

 

[TheTigerMaster]

Mixed catenary and 3rd rail also means more weight for the pickup shoes which is another thing which will need maintenance. Also, with low floor cars shoehorning more stuff in at wheel level is another PITA.

From what I've heard, 3rd rail adds a non negligible amount of friction.

 

[cplchanb]

Are the machines tunnelling towards each other? What happens when they meet?

I think I remember reading before that they might bury 1 set and extract the other....or was that for something else............

 

[TheTigerMaster]

Are the machines tunnelling towards each other? What happens when they meet?

They keep drilling into each other until one tears the other apart. The winner is declared strongest TBM in Toronto, and goes on to global championship round.


But seriously, the TBMs coming from the west will reach the extraction point at Yonge before the TBMs from the east.

 

[marcus_a_j]

They keep drilling into each other until one tears the other apart. The winner is declared strongest TBM in Toronto, and goes on to global championship round.

The next generation of robot wars.

 

[crs1026]

I think I remember reading before that they might bury 1 set and extract the other....or was that for something else............

Both sets will have to be removed in order for track to be laid through the extraction area.

- Paul

 

[AlvinofDiaspar]

I think I remember reading before that they might bury 1 set and extract the other....or was that for something else............

That's what they did for the Chunnel.

AoD

 

[Tuck]

Can the boring machines be reused?

 

[sixrings]

Can the boring machines be reused?

I have the same question since what happens if we do agree that we should do eglinton west to the airport. We would probably need to tunnel abit to just east of jane to start at the very least and then there is the section at martin grove.

 

[jcam]

Can the boring machines be reused?

They probably can be, but Caterpillar tunneling is completing its wind down after this project ends. Caterpillar had a buy-back on them, but doubt that will be exercised now. The Sheppard Subway TBMs ended up in Russia.

Historically, other manufacturers have refurbished competitors' machines, so a contractor could buy them and have someone else fix them, likely for a BRIC-country project. Turkey for example, is a huge market for used TBMs these days.

 

[dowlingm]

I think I remember reading before that they might bury 1 set and extract the other....or was that for something else............

my recollection is the west ones come out at the old bus terminal, the east ones stay buried.