"Tradeoffs between alternative technologies" [elevated rail vs subway]

[ScienceNostalgia101]

So two tradeoffs came to mind recently... the tradeoffs between subways and elevated rail, and the tradeoffs between solar panels and thermal solar.

 

So I figured I'd put them in the same thread, in case any more come to mind, or in case anyone else has any they'd like to share.

 

So of the downsides I've heard of to elevated rail, the most common I hear of are the noise, and the temperature fluctuations causing rail defects. However, I weigh this against two advantages. One, you see the town outside your window instead of only the tunnel, which, scenery for scenery's sake notwithstanding, has the added benefit of you not having to pay quite as careful attention to the station announcements as to not miss your stop because you can spot landmarks that tell you how close you are to where you're getting. Two; and this is a little more speculative; if the train packs ropes or ladders, doesn't that mean that, if it gets stuck, stranded passengers can just climb down to the surface instead of having to walk along the tunnel track carefully avoiding the third rail? Those two advantages in and of themselves notwithstanding, I'm left wondering something else; would these advantages also increase ridership to the point of reducing traffic, and therefore, reducing noise from traffic? And as for temperature fluctuations, how heavily does that depend on the temperature extremes a town gets? Would a place like Honolulu be less vulnerable to them than, let's say, Chicago?

 

For thermal solar and photovoltaics, I assume a tradeoff might depend on the economy of scale. Photovoltaics, presumably, are as efficient on a per-panel level in household use as industrial use, as I don't see why else they would be designed to be compact enough to fit on a rooftop. With thermal!solar, am I to presume that the larger the solar collector, the higher the temperature, and therefore the higher temperatures and higher thermodynamic efficiency? How do the initial costs and maintenance costs of each compare, and how does that depend on the scale on which the photovoltaics and/or thermal solar are being used?

[swansont]

1 hour ago, ScienceNostalgia101 said:

I figured I'd put them in the same thread, in case any more come to mind, or in case anyone else has any they'd like to share.

!

Moderator Note

If you want to focus on the concepts of tradeoffs that would be fine, but it looks like you want to discuss details, and our emphasis has always been one topic per thread. So if the latter is the case, you should have a thread for each technology.

 

[exchemist]

1 hour ago, ScienceNostalgia101 said:

So two tradeoffs came to mind recently... the tradeoffs between subways and elevated rail, and the tradeoffs between solar panels and thermal solar.

 

So I figured I'd put them in the same thread, in case any more come to mind, or in case anyone else has any they'd like to share.

 

So of the downsides I've heard of to elevated rail, the most common I hear of are the noise, and the temperature fluctuations causing rail defects. However, I weigh this against two advantages. One, you see the town outside your window instead of only the tunnel, which, scenery for scenery's sake notwithstanding, has the added benefit of you not having to pay quite as careful attention to the station announcements as to not miss your stop because you can spot landmarks that tell you how close you are to where you're getting. Two; and this is a little more speculative; if the train packs ropes or ladders, doesn't that mean that, if it gets stuck, stranded passengers can just climb down to the surface instead of having to walk along the tunnel track carefully avoiding the third rail? Those two advantages in and of themselves notwithstanding, I'm left wondering something else; would these advantages also increase ridership to the point of reducing traffic, and therefore, reducing noise from traffic? And as for temperature fluctuations, how heavily does that depend on the temperature extremes a town gets? Would a place like Honolulu be less vulnerable to them than, let's say, Chicago?

 

For thermal solar and photovoltaics, I assume a tradeoff might depend on the economy of scale. Photovoltaics, presumably, are as efficient on a per-panel level in household use as industrial use, as I don't see why else they would be designed to be compact enough to fit on a rooftop. With thermal!solar, am I to presume that the larger the solar collector, the higher the temperature, and therefore the higher temperatures and higher thermodynamic efficiency? How do the initial costs and maintenance costs of each compare, and how does that depend on the scale on which the photovoltaics and/or thermal solar are being used?

On the railway thing, the 3rd rail is always turned off in the event of needing to evacuate a train. In fact, on the London Underground the driver even carries (or used to) a bar to short the rails himself and trip the circuit breakers,  if the controllers don't turn it off for him. (Must make quite a bang. What fun!) II'm sure the same would happen with an elevated railway. So nobody would mess about with rope ladders.

Nobody except an utter idiot misses his stop on a railway. The trains stop at every station, they are all clearly signed and, as you say there are even recorded announcements nowadays to help the blind - and the drunk.  So there really is no reason to rely on landmarks. If you know the city well enough to recognise the landmarks, you will also know the station to get off at. 

Elevated railways are an appalling eyesore for the city and tend to cut communities in half, so pretty terrible in terms of urban planning. We have some in Docklands (Docklands Light Railway), but that is in former industrial areas so no established community is wrecked by them. London does have Victorian elevated sections of the suburban railway (and the District Line of the Underground), on brick viaducts. The arches have become garages, workshops even restaurants in some areas, but they do still cut up the neighbourhood. Underground is better, if the geology is favourable, as it was in much of London on the north bank of the Thames. To the south it is different (a lot of sand and gravel, which is far harder to tunnel through), which is why the Underground network is far more extensive north of the river.  

 

 

Edited February 28, 2022 by exchemist

[ScienceNostalgia101]

How much of a section of third rail needs to be shut off at a time? Is it a segmented shutoff as in from one station to the next? How are the passengers informed of which direction to walk towards? Does it take longer to walk to the nearest station than it would to safely secure a ladder in place from which passengers could climb down? Or would they be worried about liability if a passenger slips and falls?

 

As for knowing the landmarks vs. knowing the stations, maybe I'm speaking from my experience as a tourist in cities with subway stations, but looking up various landmarks online ahead of time and having a rough idea where to go almost "feels" more geographically intuitive than being certain you read the map of subway stations correctly. I don't recall ever missing my stop, but I do recall underestimating how much longer a London Overground from Euston to Watford Junction would take compared to a direct route. (Speaking of London, I would never have guessed stuff like the DLR would have been considered an eyesore until you pointed it out.)

 

But as I mentioned before, another benefit is scenery for scenery's sake. Is there any way of measuring the extent to which that appeals to other passengers?

Edited March 1, 2022 by ScienceNostalgia101

[Peterkin]

With regard to public transit, it's not a this-or-that proposition; it's more like this+that+those+these+the others(s). At least, that's how it works in Toronto, and I'm pretty sure other cities do likewise.  The subway runs entirely underground - under the busiest streets - in the dense urban core and most of the older boroughs. Where it was feasible, they put the rails in a little canyon, fenced off from pedestrians, so you can see daylight and vegetation from the windows, but not landmarks. (whole lot cheaper than digging tunnels!) A recording (in my memory, a pleasant mezzo voice) announces the next station in good time to get to the door. 

In the less dense suburbs, they have an elevated train, which is very quiet and smooth, with nice scenery. On the surface are streetcars, trolleys and buses (diesel, hybrid and electric), as well as shuttles to the airport and other high-demand destinations. One of these is the ferry terminal, where you can ride boats to the islands. Between the city center and the outer suburbs and not too distant 'bedroom communities', there is a fast commuter train, above ground, which has recently been extended to provide regular service to more distant places in the Golden Horseshoe area.

Cities and their transportation systems are not usually planned: they grow, adapt, branch out, diversify, upgrade, evolve.                

I just read that they're putting in a maglev train o replace the monorail in the zoo. And I forgot to mention the bike trials.

Overall, and okay city, except for the odd shooting. https://www.marsdd.com/news/10-toronto-green-projects-to-enjoy-when-the-pandemic-is-over/

Edited March 2, 2022 by Peterkin