News & Discussion: Adelaide Metro Trains

[ml69]

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

An above ground structure will always be far cheaper than a tunnel... less than half the cost.

[Goodsy]

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

An above ground structure will always be far cheaper than a tunnel... less than half the cost.

Away from the CBD it would be, but surely the cost of the disruption caused to the businesses on King William would bring that cost on par

[rubberman]

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

An above ground structure will always be far cheaper than a tunnel... less than half the cost.

Away from the CBD it would be, but surely the cost of the disruption caused to the businesses on King William would bring that cost on par

Would such a structure in King William Street ever be allowed? Given the huge fuss over road relocations due to the O-Bahn tunnel, I imagine pylons and an elevated railway over King William Street would need a lot of support. I'm not sure if I can see that.

[SBD]

An above ground structure will always be far cheaper than a tunnel... less than half the cost.

Away from the CBD it would be, but surely the cost of the disruption caused to the businesses on King William would bring that cost on par

Would such a structure in King William Street ever be allowed? Given the huge fuss over road relocations due to the O-Bahn tunnel, I imagine pylons and an elevated railway over King William Street would need a lot of support. I'm not sure if I can see that.

I see it as a pointless thought-bubble. Why bother to care about our heritage facades if they would be obscured by an aerial railway line anyway.

[claybro]

Would such a structure in King William Street ever be allowed?

Nope

I see it as a pointless thought-bubble.

Yep

[Westside]

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.

If you don't need to bore, don't. That's still a mantra used today. TBMs are still so much more complicated and expensive than cut and cover. Even New York's most recently opened line, the Second Ave subway (part) used multiple construction methods where appropriate:

Streets Construction method
Lenox–Park Avs Soft Ground Tunnels
Park–3 Avs Mined with Cut and Cover
3 Av–121 St Tunnel Boring Machine
121–120 Cut and Cover
120–117 Existing
117–114 Rebuilt as Cut and Cover
114–109 Existing
109–105 Cut and Cover
105–99 Existing
99–92 Cut and Cover
92–86 Tunnel Boring Machine
86–83 Mined with Cut and Cover
83–72 Tunnel Boring Machine
72–69 Mined with Cut and Cover
69–58 Tunnel Boring Machine
58–56 Cut and Cover
56–43 Tunnel Boring Machine
43–41 Mined with Cut and Cover
41–34 Tunnel Boring Machine
34–32 Cut and Cover
32–24 Tunnel Boring Machine
24–22 Mined with Cut and Cover
22–15 Tunnel Boring Machine
15–11 Cut and Cover
11–Hanover Undecided


With Adelaide's soft sandy base, I'm not sure how viable a TBM is anyway. TBMs are best done in rock rather than sand/soft soil for structural integrity, so a bored tunnel may need to be at quite a depth!


Oh, and picking up a previous comment, rail loops are just terrible, full stop. One single line will add great cross-town connections. What happens in a loop is you bring great inefficiencies near the join. For example, a loop through the city and then return north via Mile end is great for the incoming passengers, but passengers wanting to head north from ARS have to travel east, south, west then finally north, virtually all the way around the loop just to leave the city.

Both Melbourne and Sydney loops are terrible for this reason and both cities have new projects to send lines directly through the city.

[Aidan]

With Adelaide's soft sandy base, I'm not sure how viable a TBM is anyway. TBMs are best done in rock rather than sand/soft soil for structural integrity, so a bored tunnel may need to be at quite a depth!

That is just not true. Tunnel linings will ensure structural integrity. TBMs are best suited to the conditions they're designed for. There are three basic designs of TBM: EPB (earth pressure balance) for tunnelling through clay, Slurry for tunnelling through sand, and Hard Rock. Hybrid TBMs (essentially a 21st century innovation) bring the available choices up to seven, but varying ground conditions don't always require them — EPB TBMs can use gelling agents to tunnel through sand, and can cope with some rock. Our limestone layer wouldn't be too big an obstacle for an EPB TBM.

Oh, and picking up a previous comment, rail loops are just terrible, full stop. One single line will add great cross-town connections. What happens in a loop is you bring great inefficiencies near the join. For example, a loop through the city and then return north via Mile end is great for the incoming passengers, but passengers wanting to head north from ARS have to travel east, south, west then finally north, virtually all the way around the loop just to leave the city.

Both Melbourne and Sydney loops are terrible for this reason and both cities have new projects to send lines directly through the city.

Sydney has long had lines going through it as well as the loop (which is far from terrible as passengers all have the option of changing trains at Central). Melbourne has the option of more through services, but stupidly chooses not to use it.

Anyway, thanks for posting the Second Avenue Subway info.

[claybro]

With Adelaide's soft sandy base, I'm not sure how viable a TBM is anyway. TBMs are best done in rock rather than sand/soft soil for structural integrity, so a bored tunnel may need to be at quite a depth!


Oh, and picking up a previous comment, rail loops are just terrible, full stop. One single line will add great cross-town connections. What happens in a loop is you bring great inefficiencies near the join. For example, a loop through the city and then return north via Mile end is great for the incoming passengers, but passengers wanting to head north from ARS have to travel east, south, west then finally north, virtually all the way around the loop just to leave the city.

Both Melbourne and Sydney loops are terrible for this reason and both cities have new projects to send lines directly through the city.

Interesting list of projects with multiple methods employed. Be interesting to see how they cope with joining the various sections, getting the TBM into place then removing it ETC. different depths and other issues.
By the way, Adelaide does not have a sandy base. It is clay, and even if it was sandy, the Perth underground was built using boring machines and is in VERY sandy soil and traverses the heart of the CBD much as the Adelaide link will, as is the new airport link. (still there has been some surface subsidence problems with the Forrestfield tunnel link but thankfully not under any homes )
Have to agree on the loops though. Melbourne loop is often help up with delays of trains entering the loop, assume same issues with Sydney. Melbourne seems to have learnt from this, and the new metro tunnel from my recollection avoids the loop.

[PeFe]

The new Sydney Metro avoids the city loop, it is "through" service.

And all fuure Sydney metro train lines are to be "through" services as well.

Loops are definitely "out" in current "best transport planning" for heavy rail.

[[Shuz]]

The CBD underground proposal is not a loop, it is a through service. Check the map again a page back.

[PeFe]

Found on page 122 of the Integrated Transport and Land Use Plan (ITLUP). It's still available to view online - make the most of this before the Liberals quietly delete it and replace it with a 'page not found'.

Inner Adelaide:


CBD, including underground rail loop:

Sort of dog legs loop + direct tracks into Adelaide Station...weird mixture of commuter station terminus (a dead end) and a through metro

[Goodsy]

Found on page 122 of the Integrated Transport and Land Use Plan (ITLUP). It's still available to view online - make the most of this before the Liberals quietly delete it and replace it with a 'page not found'.

Inner Adelaide:


CBD, including underground rail loop:

Sort of dog legs loop + direct tracks into Adelaide Station...weird mixture of commuter station terminus (a dead end) and a through metro

It would be similar to Perth train station

[claybro]

Although impossible to tell from such a vague map, it does not appear to be a proper loop, more of a u shaped through tunnel. It looks like a good option for Adelaide as it covers the east end as well, gives access to the Mall(east end) and yet avoids the pitfalls as discussed of a circular loop. As for Adelaide station, I believe the underground will be a different station, but adjacent to the existing station linked by an underground walkway, as someone mentioned, similar to the Perth setup. I can say it is quite a walk via the underground link from Perth surface station to Perth underground and they don't really feel linked. I think in Adelaides case a station directly under north Terrace and linking via the existing pedestrian underpass would be a much better setup.

[claybro]

Sorry also to add, I think also the beauty of this setup would be that on Football days, special services could still access Adelaide station direct as they do now and avoid the underground section, leaving that for normal services for the North/south trains.

[SBD]

Although impossible to tell from such a vague map, it does not appear to be a proper loop, more of a u shaped through tunnel. It looks like a good option for Adelaide as it covers the east end as well, gives access to the Mall(east end) and yet avoids the pitfalls as discussed of a circular loop. As for Adelaide station, I believe the underground will be a different station, but adjacent to the existing station linked by an underground walkway, as someone mentioned, similar to the Perth setup. I can say it is quite a walk via the underground link from Perth surface station to Perth underground and they don't really feel linked. I think in Adelaides case a station directly under north Terrace and linking via the existing pedestrian underpass would be a much better setup.

It looks like it supports loop services from/to the south, and probably can handle north-south through services, but others would generally be at the existing station. north and northwest services from Adelaide would be odd if they could be on either ex-Seaford services on the loop or terminated services from the far end of the station.

I can't work out from the map where any underground station(s) in the city would be, either.