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Belair has never been intended for electrification IIRC, so it would still traverse through Mile End (presuming that remains open) and terminate at Adelaide station along with (hopefully) all interstate (and, even more hopefully, intrastate) trains.

Are there efficiencies for the North/South lines through running rather than looping?

rhino wrote: ↑

Wed Oct 31, 2018 12:10 pm

I would have expected the tracks to be laid such that a train coming in from the northern line could traverse the loop and head out to the north again, the same as trains on the southern line will be able to.

Wouldn't it make more sense for them to go all the way from Seaford to Gawler and back, there's no need to terminate in the city if they can go all the way through

Goodsy wrote: ↑

Wed Oct 31, 2018 12:37 pm

rhino wrote: ↑

Wed Oct 31, 2018 12:10 pm

I would have expected the tracks to be laid such that a train coming in from the northern line could traverse the loop and head out to the north again, the same as trains on the southern line will be able to.

Wouldn't it make more sense for them to go all the way from Seaford to Gawler and back, there's no need to terminate in the city if they can go all the way through

Because there are exceptions - work being done on one of the lines and busses being substituted for trains, a big event in the suburbs necessitating extra trains (like the soccer match last night requiring extra trams that were not made available), the Royal Adelaide Show requiring lots of shuttles. It just seems short-sighted to not allow trains to loop back to the north.

rhino wrote: ↑

Wed Oct 31, 2018 12:49 pm

Goodsy wrote: ↑

Wed Oct 31, 2018 12:37 pm

rhino wrote: ↑

Wed Oct 31, 2018 12:10 pm

I would have expected the tracks to be laid such that a train coming in from the northern line could traverse the loop and head out to the north again, the same as trains on the southern line will be able to.

Wouldn't it make more sense for them to go all the way from Seaford to Gawler and back, there's no need to terminate in the city if they can go all the way through

Because there are exceptions - work being done on one of the lines and busses being substituted for trains, a big event in the suburbs necessitating extra trains (like the soccer match last night requiring extra trams that were not made available), the Royal Adelaide Show requiring lots of shuttles. It just seems short-sighted to not allow trains to loop back to the north.

The Gawler and Seaford line would presumably still have access to the Railway station itself if they wanted to have extra services terminate there

Goodsy wrote: ↑

Wed Oct 31, 2018 1:08 pm

rhino wrote: ↑

Wed Oct 31, 2018 12:49 pm

Goodsy wrote: ↑

Wed Oct 31, 2018 12:37 pm

Wouldn't it make more sense for them to go all the way from Seaford to Gawler and back, there's no need to terminate in the city if they can go all the way through

Because there are exceptions - work being done on one of the lines and busses being substituted for trains, a big event in the suburbs necessitating extra trains (like the soccer match last night requiring extra trams that were not made available), the Royal Adelaide Show requiring lots of shuttles. It just seems short-sighted to not allow trains to loop back to the north.

The Gawler and Seaford line would presumably still have access to the Railway station itself if they wanted to have extra services terminate there

Through running most of the time would be good for people to/from the north who's ultimate destination is one of the stations further south than North Terrace.

Since the plan shows that the underground railway goes under North Terrace, what happens when it reaches the current pedestrian subway south of the existing station forecourt? Will the new station be under that subway, or does it actually deviate south and get built under the escalators on the south end?

SBD wrote: ↑

Wed Oct 31, 2018 7:08 pm

Goodsy wrote: ↑

Wed Oct 31, 2018 1:08 pm

rhino wrote: ↑

Wed Oct 31, 2018 12:49 pm

Because there are exceptions - work being done on one of the lines and busses being substituted for trains, a big event in the suburbs necessitating extra trains (like the soccer match last night requiring extra trams that were not made available), the Royal Adelaide Show requiring lots of shuttles. It just seems short-sighted to not allow trains to loop back to the north.

The Gawler and Seaford line would presumably still have access to the Railway station itself if they wanted to have extra services terminate there

Through running most of the time would be good for people to/from the north who's ultimate destination is one of the stations further south than North Terrace.

Since the plan shows that the underground railway goes under North Terrace, what happens when it reaches the current pedestrian subway south of the existing station forecourt? Will the new station be under that subway, or does it actually deviate south and get built under the escalators on the south end?

Also not everyone wants to go to the city. By running the trains through to the other side of the city, you open up more destinations without having to connect. I'd imagine a loop tunnel would be longer and more expensive than a non-looping tunnel.

One thing that seems silly about that subway is that it goes underneath the tram stop, but there are no stairs up to the tram stop. Surely that would make connecting between trams and trains easier.

1NEEDS2POST wrote: ↑

Wed Oct 31, 2018 9:25 pm

SBD wrote: ↑

Wed Oct 31, 2018 7:08 pm

Goodsy wrote: ↑

Wed Oct 31, 2018 1:08 pm

The Gawler and Seaford line would presumably still have access to the Railway station itself if they wanted to have extra services terminate there

Through running most of the time would be good for people to/from the north who's ultimate destination is one of the stations further south than North Terrace.

Since the plan shows that the underground railway goes under North Terrace, what happens when it reaches the current pedestrian subway south of the existing station forecourt? Will the new station be under that subway, or does it actually deviate south and get built under the escalators on the south end?

Also not everyone wants to go to the city. By running the trains through to the other side of the city, you open up more destinations without having to connect. I'd imagine a loop tunnel would be longer and more expensive than a non-looping tunnel.

One thing that seems silly about that subway is that it goes underneath the tram stop, but there are no stairs up to the tram stop. Surely that would make connecting between trams and trains easier.

There are no stairs or lift now directly connecting the pedestrian subway and the tram stop. If the train tracks end up directly below the tram tracks, it might be possible to build 3-stop lifts (train, pedestrian, street/tram), but if there's pedestrian access on both sides of North Terrace, is there likely to be significant need to also provide it in the middle? The tram platforms then need to be wide enough for surface-only pedestrians to get past the lift and top of the stairs without crush crowds pushing people in front of traffic nor down the stairs.

SBD wrote: ↑

Wed Oct 31, 2018 7:08 pm

Since the plan shows that the underground railway goes under North Terrace, what happens when it reaches the current pedestrian subway south of the existing station forecourt? Will the new station be under that subway, or does it actually deviate south and get built under the escalators on the south end?

It would be much easier to build it under that subway than to deviate. Not only would deviating make station construction more difficult, but there's the weight of the casino to consider as well. Even under the southern end of the station, it would be far harder to tunnel under than a road. And the subway floor isn't very much lower than the station floor.

Under the main part of the station it would be worse - the columns on the platform side of the ticket barriers are not aligned to those on the concourse side, which I think means tunnelling under the station itself would be incredibly difficult. I haven't seen details of the foundations so I could be wrong, but it certainly looks like there was a big cockup in the 1980s.

Aidan wrote: ↑

Wed Oct 31, 2018 10:52 pm

SBD wrote: ↑

Wed Oct 31, 2018 7:08 pm

Since the plan shows that the underground railway goes under North Terrace, what happens when it reaches the current pedestrian subway south of the existing station forecourt? Will the new station be under that subway, or does it actually deviate south and get built under the escalators on the south end?

It would be much easier to build it under that subway than to deviate. Not only would deviating make station construction more difficult, but there's the weight of the casino to consider as well. Even under the southern end of the station, it would be far harder to tunnel under than a road. And the subway floor isn't very much lower than the station floor.

Under the main part of the station it would be worse - the columns on the platform side of the ticket barriers are not aligned to those on the concourse side, which I think means tunnelling under the station itself would be incredibly difficult. I haven't seen details of the foundations so I could be wrong, but it certainly looks like there was a big cockup in the 1980s.

I meant the south side, putting the new station under Roma Mitchell House or Station Arcade, but now that I look at Streetview instead of guessing from memory, I don't think that could possibly work.

The unfortunate part of needing to dig deeper than the subway is how deep a lot of cut-and-cover tunnel would need to be. The alternative view might be that it could be done with a tunnel-boring machine, and share the cost with the North South Motorway. Both tunnels could then be deep enough that there is much less requirement to locate and/or relocate services that are less than five metres underground. Both tunnels should be through soft earth (not hard rock) so require the same kind of machine and engineering, which would not be the same as was used for the Heysen Tunnels (or needed for any prospective tunnel through the ridge between the SE Freeway and Waite College)

SBD wrote: ↑

Wed Oct 31, 2018 11:44 pm

I meant the south side, putting the new station under Roma Mitchell House or Station Arcade, but now that I look at Streetview instead of guessing from memory, I don't think that could possibly work.

Sorry, I should have deduced that, but its impartiality prevented me from thinking of it.

The unfortunate part of needing to dig deeper than the subway is how deep a lot of cut-and-cover tunnel would need to be.

North Terrace is on a slope. The ground level outside the station's main entrance is already at least 4m higher than at the Morphett Street Bridge end. A shallow tunnel could be worse from a passenger perspective, as they'd have to go down beneath the railway and then up again to access the station.

The alternative view might be that it could be done with a tunnel-boring machine, and share the cost with the North South Motorway.

The large diameter TBMs used for road tunnels are unlikely to be cost effective when constructing rail tunnels.

Both tunnels could then be deep enough that there is much less requirement to locate and/or relocate services that are less than five metres underground. Both tunnels should be through soft earth (not hard rock) so require the same kind of machine and engineering,

What's tunnelled through depends on what's there. Soft ground would be preferable, but if it intrudes into the limestone layer then so be it.

which would not be the same as was used for the Heysen Tunnels

IIRC they encountered quartzite (which is much harder) there, so used a roadheader.

(or needed for any prospective tunnel through the ridge between the SE Freeway and Waite College)

Has anyone thought of that besides us?

Why go under the city when you could go above just like Chicago in USA, you'd have shade underneath the above ground railway from the warm summer sun

SBD wrote: ↑

Wed Oct 31, 2018 11:44 pm

The unfortunate part of needing to dig deeper than the subway is how deep a lot of cut-and-cover tunnel would need to be. The alternative view might be that it could be done with a tunnel-boring machine, and share the cost with the North South Motorway. Both tunnels could then be deep enough that there is much less requirement to locate and/or relocate services that are less than five metres underground. Both tunnels should be through soft earth (not hard rock) so require the same kind of machine and engineering, which would not be the same as was used for the Heysen Tunnels (or needed for any prospective tunnel through the ridge between the SE Freeway and Waite College)

As some parts of the tunnel will not be directly under roads, I don't believe a cut and cover method would be used. Therefore if a boring machine is used, any stations can really go anywhere, and only the pedestrian portals need to be taken into account on the surface. In this case, surely it would be possible to use the existing pedestrian subway under North Terrace as access to escalators down to the lower station. This would give pedestrian access to either side of North Terrace, and the existing railway station concourse with through access to the riverbank or Casino via Adelaide station ETC.

Eurostar,
Elevated railways would be regarded as unsightly in our City streets, and the noise of the trains affects a much larger area. Though Chicago does have elevated sections (including a CBD loop) there are underground sections as well.

claybro, keep in mind that the tunnel doesn't all have to be all constructed by the same method.

Would elevated lines in the city even be cost effective these days? you could make the case that elevating a line down King William rather than cut and cover would have been preferable back in the day. But surely a TBM chugging away underground would be cheaper

Aidan wrote: ↑

Thu Nov 01, 2018 3:22 pm

claybro, keep in mind that the tunnel doesn't all have to be all constructed by the same method.

Agreed. But if they have to go to the expense of getting in a boring machine for some sections, it would be better to keep it on the whole project? Bearing in mind, there will be a significant difference in the depth of bored tunnel as opposed a cut and cover tunnel, and lining these up will add to the cost and difficulties.