The O-bahn

[Cruise]

With the price of Oil going over US $100 a barrell for the first time today, you can be sure more people will be looking to use PT as their cars become to expensive to run all the time.

No they wont, driving is to damn convenient. Ive said it before and I'll say it again I would catch PT to work and everywhere else if it well, existed when i finished work. (I finish work early in the morning)

[Bulldozer]

All structural concrete is reinforced with steel. Even street kerbing is reinforced. Without the steel concrete falls apart when tensile forces are applied.

I've heard of a few cases where structural concrete hasn't been reinforced with steel (though it is very rare these days). The concrete doesn't exactly fall apart as such, but the concrete is riddled with large cracks and is very weak in tension. Best example of it around Adelaide is in the stobie poles that are broken but still standing, buckled steel and chunks of concrete missing and cracked.

Stobie poles are reinforced - look up the sides of the steel beams and see the bolts that hold them together Urban is right - concrete takes compressive loads very well, but it can't take shearing or tensile forces. Steel is the opposite, and that's why concrete is combined with steel

As for the O-bahn though, it's a nice idea but the reality of the situation is that it's not going anywhere and even if you built O-bahn tracks all over Adelaide we still wouldn't have the economy of scale to support the manufacture of buses for it. Rip it up and replace it with heavy electric rail - more capacity and faster than light rail and probably cheaper to run than buses.

[kernelpanic]

I'm a regular user of the O-bahn, and I think it's fantastic. If it were replaced by a rail system, I suspect there'd be a lot of congestion at either end of any track as commuters changeover to cars or buses to go on. THe beauty of the O-bahn, as already stated by other posters, is it's ability to then go on to different destinations within the city or suburbs. There must be some efficiencies in this model that rail can't provide, but I'm ust guessing.

Anyyone have any data or ideas about this?

[Shuz]

Well, I'm fairly sure a rail line can't be supported anyway. Something about the soils, close proximity to the Torrens (although probably not relevant anymore, now that the system is being electrified). But yeah, I think the soil would sink in with the weight of the tracks and sleepers and stones, not to mention a much higher risk of services being affected due to flooding.

Despite all these inconviences, I believe that if mankind can master engineering projects much riskier than this one, then a rail line should be built.

[Cam]

El Taco says what about combining both O-bahn and Tram on the same line.

[monotonehell]

El Taco says what about combining both O-bahn and Tram on the same line.

The OBahn track has the provision for both tram tracks down the centre as well as over head electrification. Although this provisioning was made back in the days of sensible bus and tram layouts (not this new low floor crap which causes vibrations and so on ) so I'm unsure if the current gauge would fit. If anyone wants I can take a measuring tape to the obahn test track Also can rail handle the grade around Holden Hill?

(Also who's El Taco?)

[Aidan]

Well, I'm fairly sure a rail line can't be supported anyway. Something about the soils, close proximity to the Torrens (although probably not relevant anymore, now that the system is being electrified). But yeah, I think the soil would sink in with the weight of the tracks and sleepers and stones, not to mention a much higher risk of services being affected due to flooding.

Despite all these inconviences, I believe that if mankind can master engineering projects much riskier than this one, then a rail line should be built.

Of course it is possible to build a railway line there. It is difficult ground, but not much more difficult than elsewhere in Adelaide.

But where there is no existing rail or express road infrastructure, and large tracts of low density sprawl need linking with a high density CBD, and the density in the suburbs between them is also fairly low, and most freight is on a different axis, an O-bahn is the best choice. These circumstances (which apply to the NE suburbs of Adelaide) are rather unusual, which is part of the reason there are so few O-bahns elsewhere. And the decision to go with an O-bahn was rather a fluke, but time has proven it correct.

It would be much better if they added a fast way for the buses to get into (and possibly through) the City, and used newer buses (preferably electric ones, possibly in the form of hybrids) but that it doesn't is not a criticism of the O-bahn technology - it's lack of money that has prevented any inward extensions, and lack of need that has prevented any outward extensions. And if we'd opted for light rail instead, the state debt that held Adelaide back for a decade would've been even higher, and our light rail line would be high floor and wouldn't go to Adelaide station.

[Aidan]

All structural concrete is reinforced with steel. Even street kerbing is reinforced. Without the steel concrete falls apart when tensile forces are applied.

Unreinforced concrete is sometimes used where it is not expected to be subjected to significant tensile forces. A good example is the tram track from Victoria Square to City West.

[monotonehell]

Of course it is possible to build a railway line there. It is difficult ground, but not much more difficult than elsewhere in Adelaide.

But where there is no existing rail or express road infrastructure, and large tracts of low density sprawl need linking with a high density CBD, and the density in the suburbs between them is also fairly low, and most freight is on a different axis, an O-bahn is the best choice. These circumstances (which apply to the NE suburbs of Adelaide) are rather unusual, which is part of the reason there are so few O-bahns elsewhere. And the decision to go with an O-bahn was rather a fluke, but time has proven it correct.

It would be much better if they added a fast way for the buses to get into (and possibly through) the City, and used newer buses (preferably electric ones, possibly in the form of hybrids) but that it doesn't is not a criticism of the O-bahn technology - it's lack of money that has prevented any inward extensions, and lack of need that has prevented any outward extensions. And if we'd opted for light rail instead, the state debt that held Adelaide back for a decade would've been even higher, and our light rail line would be high floor and wouldn't go to Adelaide station.

*sob* I think I love you I've said all these things in the past but the gunzels just hold their hands to their ears and sing "Down By the Station" loudly.

All together now ...
Down by the station
Early in the morning
See the little pufferbellies
All in a row
See the station master
Turn the little handle
Puff, puff, toot, toot
Off we go!

[jk1237]

very funny, however Aidan, how do you know that time has proven the obahn to be the correct choice. IMO its the opposite, as every other city in the world has shown trains to be the better way. I'm comparing our NE suburbs to a similar corridor to the north of Perth that they were going to put a busway in, but decided to put in a electric train that I believe carries far more than our o'bahn, in much quiet, spacious and air conditioned style. I do admit there would have been a logistical problem of how to connect the track from the north-east to the rest of the network (if we went for a train line), but a railway line would have paid for itself by now, and it would have been a catalyst for the upgrade of the rest of the train system 20 years ago, not the next 20 years when it costs 4 times as much.
If we were concerned with state debt back then, they should have just built a normal bitumen road only for buses to Modbury, without spending millions more on a large concrete track.

Anyway, the o'bahn's here to stay so I'll shutup now

[monotonehell]

very funny, however Aidan, how do you know that time has proven the obahn to be the correct choice. IMO its the opposite, as every other city in the world has shown trains to be the better way. I'm comparing our NE suburbs to a similar corridor to the north of Perth that they were going to put a busway in, but decided to put in a electric train that I believe carries far more than our o'bahn, in much quiet, spacious and air conditioned style. I do admit there would have been a logistical problem of how to connect the track from the north-east to the rest of the network (if we went for a train line), but a railway line would have paid for itself by now, and it would have been a catalyst for the upgrade of the rest of the train system 20 years ago, not the next 20 years when it costs 4 times as much.
If we were concerned with state debt back then, they should have just built a normal bitumen road only for buses to Modbury, without spending millions more on a large concrete track.

Anyway, the o'bahn's here to stay so I'll shutup now

Jk1237, Aidan said exactly why in his post...

But where there is no existing rail or express road infrastructure, and large tracts of low density sprawl need linking with a high density CBD, and the density in the suburbs between them is also fairly low, and most freight is on a different axis, an O-bahn is the best choice. These circumstances (which apply to the NE suburbs of Adelaide) are rather unusual, which is part of the reason there are so few O-bahns elsewhere. And the decision to go with an O-bahn was rather a fluke, but time has proven it correct.

The alternative with a rail line during rush period would be dozens of buses running all over the NE suburban sprawl, doing short runs feeding hundreds of passengers into the head of the rail line at Tea Tree Plaza. Forcing them to wait for a train for a very short run into the CBD. Instead of the continuous flow of passengers who have a door to door service that we have with the OBahn.

I catch the OBahn into work and back home, I catch a bus up my road and it runs express into Grenfell street around 100m from my office, then the same back home. If the OBahn corridor were a rail route, it would be much less convenient.

[jk1237]

The alternative with a rail line during rush period would be dozens of buses running all over the NE suburban sprawl, doing short runs feeding hundreds of passengers into the head of the rail line at Tea Tree Plaza. Forcing them to wait for a train for a very short run into the CBD.

Actually, thats exactly how I would have done it, and how I would have it everywhere. Thats how Perth's northern line works and is very successful. Why waste all those buses and drivers going all the way into town, when 1 train can do it every 10-15 mins. You have to interchange outside of peak hour at Modbury and Paradise on many routes, nowadays, anyway. Sorry, I said I was gonna shutup

[Norman]

Actually, the Joodaloop line runs every 5-7 minutes

[monotonehell]

The alternative with a rail line during rush period would be dozens of buses running all over the NE suburban sprawl, doing short runs feeding hundreds of passengers into the head of the rail line at Tea Tree Plaza. Forcing them to wait for a train for a very short run into the CBD.

Actually, thats exactly how I would have done it, and how I would have it everywhere. Thats how Perth's northern line works and is very successful. Why waste all those buses and drivers going all the way into town, when 1 train can do it every 10-15 mins. You have to interchange outside of peak hour at Modbury and Paradise on many routes, nowadays, anyway. Sorry, I said I was gonna shutup

That makes sense on longer runs, like the Gawler line, but on short runs a shuttle train would just be annoying. You'd have the cost of the train as well as all the feeder buses, this way you only have the cost of the buses.

There's been a few papers on the subject that I've read, here's one of them from back in 1992...
http://www.patrec.org/atrf/papers/1992/ ... (1992).pdf

Not exactly a glowing recommendation, in fact it suggested that in 1992 it couldn't be justified economically, but if you read it you'll see that the OBahn fits the requirements of the NE sprawl better than rail or bus networks.

[Will409]

Well, I'm fairly sure a rail line can't be supported anyway. Something about the soils, close proximity to the Torrens (although probably not relevant anymore, now that the system is being electrified). But yeah, I think the soil would sink in with the weight of the tracks and sleepers and stones, not to mention a much higher risk of services being affected due to flooding.

Despite all these inconviences, I believe that if mankind can master engineering projects much riskier than this one, then a rail line should be built.

The purpose of ballast is to spread the load of the rails/sleepers as well as the rollingstock when it goes over it over poor soil. Dump enough ballast in and you should be fine. Besides, the Noarlunga line south of Hallet Cove goes through some pretty dodgy soil and yet we are (barely) able to reach 90km/h.

As an aside about railway flooding, the Commonwealth Railways ran the old narrow gauge Ghan through water upto 2ft deep before dieselisation without any major issues (other then the train arriving 2 weeks late).