Science desk
< January 21	<< Dec \| January \| Feb >>	January 23 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

January 22[edit]

Public transit[edit]

What are the fundamental distinctions between light rail, rapid transit and commuter railroads (in other words, what exactly are the qualities which make light rail not rapid transit, or rapid transit not a commuter railroad, etc.)? Are there precise terms for transit systems (like BART, PATH, Chicago South Shore & South Bend Railroad, the S-Bahns in Germany, Norristown High-Speed Line, the Washington Metro, etc.) which combine the characteristics of 2 (or even all 3) of these categories? 2601:646:8A81:6070:1C69:D1A5:F58B:F3D2 (talk) 09:32, 22 January 2023 (UTC)[reply]

None, really. Sometimes there's a legal difference based on some 100 year old law that's not particularly applicable any more, in other cases it's purely about PR. Tramways (not the aerial ones), metros, commuter trains, intercity trains and high speed trains form a continuum without any clear, fundamental divisions. PiusImpavidus (talk) 11:40, 22 January 2023 (UTC)[reply]

Just by mousing over the 3 articles, it kind of explains it in the 1st sentence. Light rail is a combination. Rapid transit has included for subways. Commuter appears to be 100% scheduled. So some of the rapid transit are not 100% scheduled, except at night service for example, but during day rush hour, can say "every 7-12 minutes" for example. 67.165.185.178 (talk) 14:40, 22 January 2023 (UTC).[reply]

Even when they say: “There's a train every 7–12 minutes,” there's usually a schedule. It's not communicated to the public very clearly, but often you can find it. Underground services in central London are so frequent that most people don't care about the schedule. There are 24 trains per hour from Liverpool Street to Baker Street, but only 2 of those proceed to Chesham, which are the only trains serving Chesham, so if that's your destination, you want to know the schedule. Also to make sure tracks, trains and crew are available and services don't bunch up. PiusImpavidus (talk) 12:01, 23 January 2023 (UTC)[reply]

There's a difference between light rail which is a modern urban system and Light railway which (in the UK) is a railway built to lower standards by an order under the Light Railways Act 1896. Martin of Sheffield (talk) 17:53, 22 January 2023 (UTC)[reply]

Most NYC Subway cars are 10ft wide, 12.08-12.13ft tall, 60 or 75ft long, 1146mm platform height, up to ~60-65 short tons laden (40.485-46.36 short tons empty) and 10 or 8 cars whatever equals 600ft. The other cars are as little as 8.6ft wide, 11.89ft tall, 51.04ft long, 1111mm platform height, ~50 short tons laden (33.15 short tons empty), 10 or 11 car train. There's a ~58.1 short ton (including diesel and driver) work loco that's the max weight a 53.27ft car can be and still go anywhere. In all cases rail is standard gauge, 3rd rail 600 or 625 volts DC, acceleration 2.5mph/s, speed (if enough room to accelerate) is 55-90 mph, cross section like that or similar and height measured from the top of the non-3rd rails. Is that medium rail or heavy rail? (does medium exist?) Sagittarian Milky Way (talk) 05:54, 23 January 2023 (UTC)[reply]

They may not meet the (very strict) crash worthiness rules of American heavy rail, making them legally light rail. That's just a technicality; I think that those NYC Subway cars can and are allowed to run almost unmodified on the mainlines in SE England (London to Dover etc.), where they would be considered heavy rail. PiusImpavidus (talk) 12:01, 23 January 2023 (UTC)[reply]

I was wrong: only the retired R44's could reach 87.75 mph (still accelerating!) on a 5.9 mile test track of commuter rail with suburb-like station spacing, using 650 volts to do so (77 mph with half the axles off to simulate loaded mass, they hoped to build the 2nd Avenue subway before that train model retired so it could get enough rail quality to exceed upper 50s mph subway service for the first time). The best design speed in an article for a current model is 70 mph

. Sagittarian Milky Way (talk) 17:08, 23 January 2023 (UTC)[reply]

Here’s a fun tidbit about public transport in the greater Paris region. One of the layers of rail transportation is the Réseau Express Régional (better known by the acronym RER). The operation of some RER lines is split between the RATP (the operator of most urban transport in the greater Paris region) and SNCF (the rail company that operates long-distance trains). Even though there is decent coordination, they still each have their own internal regulation and technical choices, hence much hilarity ensues. For instance the locomotive needs to switch between two different tensions of overhead line (link, in French).

So, yes, as PI said, there’s a continuum. Tigraan^{Click here for my talk page ("private" contact)} 10:25, 23 January 2023 (UTC)[reply]

Using 25 kV in a metro tunnel is a bit problematic, as it requires big clearances, so this makes some sense. PiusImpavidus (talk) 12:01, 23 January 2023 (UTC)[reply]

The general distinction between "light rail" and "rapid transit", IIRC, is that "light rail" is not grade-separated from other modalities, whereas "rapid transit" is; light rail includes things like streetcars and trams that run on rails alongside of cars, whereas rapid transit has its own dedicated right-of-way, either as a subway or elevated train. Some light rail may have partially dedicated rights of way, but they will generally run on ground level, and have at-grade crossings with roads. You'll notice that all of the images of light rail in the Wikipedia article linked above show ground-level rail systems. Rapid transit pretty much always has a dedicated right-of-way and does not usually have any road crossings, and it most commonly runs at a different grade than road transit, though not 100% of the time. There is even something called Bus rapid transit, where it has the features of a rapid transit system (boarding at dedicated stations, paying at the station and not on the vehicle, dedicated right-of-way) though it doesn't of course run on rails. --Jayron 32 13:00, 23 January 2023 (UTC)[reply]
Do you know why some cities don't mind San Fran-style rails in the street and others go to great lengths to avoid streetcars and trams and even buses that don't look like rapid transit? If it's so dangerous New York got rid of them why do so many advanced European cities and Baltimore have them? Some Manhattan buses are 2 full-sized buses joined end-to-end by a swivel you can walk through, they don't seem safer than a tram and make more noise than a bus. Sagittarian Milky Way (talk) 15:56, 23 January 2023 (UTC)[reply]

The reason is that there are advantages and disadvantages to separating them and having them joint, as well as reasons for having one solution over the other at specific places. I can't speak for SF or NY, but cities along the likes of Gdańsk, Wrocław and Kraków in Poland will, in certain areas, have, say, street traffic crossing pedestrian areas without any barriers at all, with heavy separation elsewhere, all in the same city. The reasons simply are that it's more convenient to hope for human carefulness at some locations, sacrificing a certain degree of safety, while choosing separation to provide higher transit speeds and more safety elsewhere. The design philosophy is based on the specific small section of the transport network. --Ouro (blah blah) 02:31, 24 January 2023 (UTC)[reply]

The main reason why cities went away from public-transit (street cars, trams, and light rail) is that they moved towards car-oriented urban planning. The kind of city you build when you expect everyone to drive looks very different from the kind of city you build when you expect everyone to walk to work and/or ride public transportation. Streetcar suburbs look very different than modern car-oriented suburbs. When you design for public transit, that is called transit-oriented development, and generally involves designing for mixed-use development with a high Urban density. The modern American city is instead mostly built with heavily segregated uses mandated by zoning laws, and most housing is either single-family homes or at most medium-density housing, but which is often miles from places where people shop and work. The combination of the car and the single-family-home suburbs (i.e. Levittowns) drove this kind of development, which killed public transportation in the U.S. As people moved into low-density housing, ridership on public transit plummeted, and most cities shut down their transit systems as they became highly unprofitable. --Jayron 32 19:08, 24 January 2023 (UTC)[reply]

There was some movement to make European cities more car-oriented in the 1960s and '70s, but the disadvantages of that became clear very soon, so that movement mostly stopped. Most smaller cities closed their tram systems around 1960, but the large cities kept them and even expanded the tramways as the city grew. Long-distance tramways were closed and replaced by diesel buses, feeding to railway stations in a centrally planned public transport system. In Europe, cars only became available for the masses in the 1960s and even in the 1980s city planners assumed less than one car per family, which of course caused parking problems 20 years later, when the number of cars had increased to slightly more than one per family. High population density makes low density housing a problem, as that takes away too much agricultural land and nature. Then there's a willingness to pay subsidies for facilities that are considered beneficial but not viable in a free market and (quite successful) promotion of bicycles for commuting.

Summarising: a later mass introduction of cars, a higher population density and less confidence in the free market explain much of the difference between Europe and the US.

BTW, those bendy buses are popular in Europe too. I've even encountered 24.8 m (81 ft) long buses with two bends. Except in the UK, which prefers double-deckers. PiusImpavidus (talk) 10:32, 25 January 2023 (UTC)[reply]

These busses are called articulated buses (bi-articulated for two bends), and there's even a double-decker variety. --Wrongfilter (talk) 10:44, 25 January 2023 (UTC)[reply]

They're not just for tourists anymore ($45 double deckers with a narrator and almost no superstructure, just enough that you'd have to jump on purpose to fall off) Sagittarian Milky Way (talk) 16:44, 25 January 2023 (UTC)[reply]

Double deck buses, trolley buses and trams never were "just for tourists". Over here they've been normal "since Noah was a kid". Perhaps you need to specify where. BTW, the link doesn't work properly, it just sits there with an empty box superimposed on what looks like a sapphire bus. Martin of Sheffield (talk) 17:10, 25 January 2023 (UTC)[reply]

In the UK they're normal since Noah was a kid, in New York City they're 45 dollars, have New York Sightseeing, City Sights NY etc in big letters on the side and have an employee on public address system telling riders things like "The next street is the street from Miracle on 34th Street. And if you look to your right now that's the 485 yard tall Empire State Building, if you look overhead you can see how tall that looks up close". If you Google New York city double decker bus you can see what they look like. In 2018 the same agency that runs the subways and buses got its first double decker too but with roof, much lower fares and no narration though. Sagittarian Milky Way (talk) 17:50, 25 January 2023 (UTC)[reply]

They were normal in the U.S. as well prior to the early-to-mid 20th century. The town I grew up in had a trolley until the 1940s, and it was a town of about 3000 people at the time. Los Angeles once had an extensive street car network, the Pacific Electric and Los Angeles Railway were, combined, the largest transit system in the U.S. and possibly the world at the time, and New York once had an extensive trolley system, the Brooklyn Dodgers were named after the teens in Brooklyn who used to "dodge" the numerous trolleys that ran all over the city. Most of the streetcar/trolley/tram infrastructure had to be torn out to make car-friendly streets, and bus systems also saw a huge loss in ridership, many lines shutting down, as they generally aren't as popular due to getting clogged up in car traffic. --Jayron 32 18:16, 25 January 2023 (UTC)[reply]

I was talking about double decker buses but yes, American light rail used to be awesome. Sagittarian Milky Way (talk) 18:39, 25 January 2023 (UTC)[reply]

Until the 1940s-1950s, major US cities had double decker bus lines. New York's Fifth Avenue Coach Line ran them: [1] This was normal, "for New Yorkers" public transit, and not a tourist trap. Chicago had over 200 such buses in service, run by the Chicago Motor Coach Company, again, not a tourist trap, just normal public transit. So yes, today they are rare. In the time period we were talking about, they were as familiar a sight in New York and Chicago as they were in London. --Jayron 32 19:01, 25 January 2023 (UTC)[reply]

Wow everything was better for public transit fans in the golden age. I don't know if US public transit is improving or still worsening on average but here public transit's at least improving slowly (even light rail construction in Jersey), a lot slower than the 1830s to 1930s though. Heavy rail tunnels seem to cost like $11.1 billion now and take a bazillion years for 2 miles, in the past they built a third the entire subway in 1929-39 and only charged 5 cents (worth ~61.2 Dec '22 cents on the last day of 5 cents (6/30/1948)). Sagittarian Milky Way (talk) 23:32, 25 January 2023 (UTC)[reply]

Urban planning killed public transportation. It's a no-go in any city still planning for low-density single-family homes and widely single-purpose separated zoning districts. Successful public transit systems rely on multi-use zoning, especially intermixed commercial and residential, and high-density development. Very few North American cities are set up that way, and those that are planning in that way (Portland, a bit, maybe a few other places) are rare. Most are locked in to car-oriented development, which is incompatible with public transit. Cars need freeways, and each freeway lane can serve about 1900 cars per hour. Let's assume a 6 lane freeway, three going into the city center, and 3 coming out. Most workers drive themselves, but even accounting for buses and carpooling, lets say 1.5 persons per vehicle. That means that the freeway can accommodate, during rush hour, 1.5*1900*3 = 8550 people. Lets look at heavy rail rapid transit by comparison. Here are the numbers for the New York Subway: [2] Even the lowest capacity trains carry 59,000 passengers per hour. It's no contest. The problem is, you need a walkable catchment area around a transit stop to get those passengers to fill those trains. Single family homes don't produce enough passengers within a walkable distance to a transit stop to make the system worthwhile. --Jayron 32 12:02, 26 January 2023 (UTC)[reply]

I assume you mean "light rail construction in New Jersey, USA". I've not heard of any rail projects in Jersey recently. Martin of Sheffield (talk) 09:37, 26 January 2023 (UTC)[reply]

"Jersey" by itself could be ambiguous. If he had spelled it "Joizy", it would have been clear. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:38, 26 January 2023 (UTC)[reply]

Organic vs. non-organic foods.[edit]

Are there any foods that we buy more of that are organic, than non-organic? Like what organic foods have the highest % ratio than non-organic foods. I hear maple syrup is up there. Even though I'm from U.S., I will take answers from around the world.

For an econ question, what organic foods have the highest % more expensive relative to their conventional counterparts?

And for a science question, there are foods that are relatively the same between organic and non-organic. Such foods have thick peels (like bananas, and oranges) or have a shell (walnuts) meaning if you buy those organic it won't be much of a difference. Those were examples I were told. Probably the biggest chemical differences are in berries and leafy vegetables. 67.165.185.178 (talk) 14:37, 22 January 2023 (UTC).[reply]

Foods gathered from the wild could well be in that "organic" category, such as hunted game, or wild caught fish. Even salt ridiculously falls into the food organic definition, even if it is inorganic. Some varieties of honey would also be "organic" (ie not from farms). Graeme Bartlett (talk) 21:12, 22 January 2023 (UTC)[reply]

To answer this question meaningfully, we would need a clear, universal, unarguable definition of "organic". There isn't one. When I studied Science at university half a century ago, organic meant compounds containing carbon. This means that all food is organic (though not salt). Since then the word has come to mean whatever someone who wants to sell you something wants it to mean. HiLo48 (talk) 23:11, 22 January 2023 (UTC)[reply]

That's a little silly. Words have different meanings in different contexts all of the time. You are (incorrectly) using a chemistry context definition of "organic," but there's no reason that has to be the same definition used in food science. BTW, your definition is incorrect since inorganic carbon is a thing that exists. --OuroborosCobra (talk) 23:19, 22 January 2023 (UTC)[reply]

We still need a clear, universal, unarguable definition of "organic". Any meaning of a word that has only come into existence in the past 50 years is unstable, and with this particular one being so heavily used for marketing, even more critical. Note that the OP mentioned taking answers from around the world too. HiLo48 (talk) 23:29, 22 January 2023 (UTC)[reply]

USDA organic has a very specific legal certification and meaning. In the EU there is "biologique" and such[3], so, it just depends on the jurisdiction. But organic is not just marketing and there are legal requirements for what may brand itself as organic. Andre🚐 23:34, 22 January 2023 (UTC)[reply]

Agreed. It's not JUST marketing. But the word is heavily used as a marketing term, and once that happens, truth has little to do with its meaning. HiLo48 (talk) 02:27, 23 January 2023 (UTC)[reply]

Eh, I mean, if you advertise a product as organic in the US and it is actually processed or made with preservatives that aren't considered organic, that would open you up to fines, class action suits, or product recalls. Andre🚐 03:50, 23 January 2023 (UTC)[reply]

This is a global encyclopaedia. 95% of the world's population do not live in the USA, and it really annoys that 95% when Americans behave as if US law is all that matters. HiLo48 (talk) 05:07, 23 January 2023 (UTC)[reply]

I did make reference to the EU as well. I'm sure there are at least a few other places where organic has a legal meaning. It's not my area of expertise to speculate on the law in other places but, we have a List of countries with organic agriculture regulation and there are quite a number of other places in Latin America and Asia and other locales with organic agriculture regulation. Andre🚐 05:11, 23 January 2023 (UTC)[reply]

In my first comment I said we need a clear, universal, unarguable definition of "organic". Your description of things means we obviously don't such a single definition. HiLo48 (talk) 05:15, 23 January 2023 (UTC)[reply]

Well, my point was that organic is not just a marketing term in many places. In fact in many places, probably accounting for a good portion of the world's population, it is quantitatively different to purchase organic products in a measurable, scientific way. Andre🚐 05:20, 23 January 2023 (UTC)[reply]

I totally agree that it's not JUST a marketing term. In fact, I ready did agree with that. You're going round in circles. HiLo48 (talk) 05:29, 23 January 2023 (UTC)[reply]

The OP stated that they are in the US, so one may presume that they are using the US definition of "organic". It's less clear what they mean by "we" in "foods that we buy". Depending on where one lives and where one shops, there may be a very different proportion of organic vs. non-organic food. Some markets specialize in organic food and one may well find that a particular item has a higher proportion of organic food that one wouldn't find if they shop at a conventional supermarket. CodeTalker (talk) 06:22, 23 January 2023 (UTC)[reply]

It's older than that. ←Baseball Bugs ^{What's up, Doc?} carrots→ 00:02, 23 January 2023 (UTC)[reply]

The first citation of this sense in the OED is from 1960, so yes, it's marginally older than 50 years, but not enough to quibble about in this context. CodeTalker (talk) 03:48, 23 January 2023 (UTC)[reply]

On newspapers.com (pay site), I looked for the expression "organically grown". The first usages of it pertaining to foods start to appear in 1946. The older term seems to be "Natural foods", which goes quite a ways further back, and is also used as a marketing term. ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:54, 23 January 2023 (UTC)[reply]

See our article Organic food and note that the second sentence opens with, "Standards vary worldwide". That is often the case for foods. For example, US eggs may not be sold in the EU and vice versa, since their respective standards for eggs are mutually incompatible. There is, nevertheless, sufficient commonality in the concept that is subject to these standards for a meaningful discussion transcending the borders. --Lambiam 00:36, 23 January 2023 (UTC)[reply]

I like what someone said that 95% of the world does not live in the U.S. But not wholly relevant, especially from a Wikipedia point of view. China for example, does not have http Internet. They have their own Internet-system. So it isn't an issue for them, trying to bypass is illegal in China too I believe. And there's probably a bunch of 3rd world countries that are very inactive on the Internet by the %. 67.165.185.178 (talk) 22:42, 24 January 2023 (UTC).[reply]

I wonder what percent of native English speakers live in America. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:20, 25 January 2023 (UTC)[reply]

List of countries by English-speaking population should help answer your question. --Jayron 32 12:07, 25 January 2023 (UTC)[reply]

About 1% [4] 😄 NadVolum (talk) 12:23, 25 January 2023 (UTC)[reply]

Many of whom I don't understand when they open their mouths. 😕 --Lambiam 19:37, 26 January 2023 (UTC)[reply]

Well, sometimes that is due to the dialect, but more often it's the content... --Stephan Schulz (talk) 16:57, 27 January 2023 (UTC)[reply]

Studying the James Herriot books can help. ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:19, 27 January 2023 (UTC)[reply]