Quote:
Originally Posted by officedweller
|
While it is true that the Canada Line's lower cost can largely be explained by the cut-and-cover construction as opposed to full bored tunnel, another problem with the Eglinton Crosstown is the idiocy of using at-grade LRT technology in a mostly tunneled rapid transit scenario. I don't know what head engineer decided that, but it happened, and it's complete idiocy. Overhead caternaries make tunnels taller and more expensive.
As I posted earlier on tunnel size:
Quote:
Originally Posted by xd_1771
Hey guys, here's something I dug up while doing some searching about Kuala Lumpur's Kelana Jaya Line.
http://www.jfem.com.my/files/industries/mc_putra.html
This is the TBM used in the KJL's long tunnel sections. According to the site it had a 5.37m diameter - substantially narrower than the diameter of the TBM used for the Canada Line (6.1m). You can thank LIMs for such a small diameter and the associated savings!
|
Whereas the Eglinton LRT tunnel diameter is 6.5m, the tunnel diameter for the Canada Line (third rail) was 6.1m, and for a SkyTrain-type installation with linear motors as small as 5.37m - i.e. 80% the size and material of the Eglinton tunnels.
Here's something from a
Bombardier report [CLICK HERE] on how smaller tunnel size can have savings:
Quote:
|
Depending on the tunnel design (single track, dual track, cut and cover, with or without emergency walkway, etc.) and weather it is in solid rock or some other material, the savings due to reduced tunnel diameter can be very significant. Based on the minimum size of (single track) tunnel for both conventional and ART technology, the reduction in amount of material removed would be approximately 10,000m3 per km of dual tunnel. The amount of tunnel liner material would also be reduced, by approximately 1900m3 per km of dual tunnel. These estimates are based on a 5.0m finished tunnel diameter for ART, and 5.5m finished tunnel diameter for conventional trains, with 0.6m thick tunnel lining.
|
The cost savings of smaller tunnels would have more than absorbed the $360m cost to convert the Scarborough RT to be able to use ART 200 or 300 vehicles, for continuous operation on the Scarborough RT and the new Eglinton Crosstown lines at high capacities. The technology choice might even absorb any extra cost to make the proposed future westward extensions grade-separated and fully compatible (which would pretty much only need to be overpasses at widely-spaced intersections, if you look at the Eglinton right-of-way there).
The issue, I guess, is that no one ever bothered to look at this stuff. It was dismissed waaayyy too fast. Examining 'SkyTrain technology' could have saved Toronto from a lot of the debating, and a lot of the financial hurdles.