Wikipedia:Reference desk/Archives/Science/2018 December 13

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December 13

The need for cooler roads

I thought about it and realized that painting an asphalt road with white paint is effectively adding more work on road maintenance. Wouldn't using concrete be a cheaper alternative?--Arima (talk) 07:44, 13 December 2018 (UTC)

According to this site, asphalt has the advantages of being quicker to complete, cheaper to build (although the shorter lifespan may negate this in the long term), easier to repair, and safer. From personal experience they are also more pleasant to drive on (they have a slight give in them that makes for a smoother ride, although apparently this results in worse fuel economy). Iapetus (talk) 09:09, 13 December 2018 (UTC)

Yes, the disadvantages outweigh the advantages Concrete#Roads. 86.131.187.141 (talk) 11:11, 13 December 2018 (UTC)

It isn't paint. It is asphalt with some stuff in it to make it white and a good surface coat. Dmcq (talk) 13:42, 13 December 2018 (UTC)

If you happen to be near an oil refinery, asphalt is essentially free. They try to maximize gasoline and diesel fuel but they often end up with more natural gas and asphalt then there is a demand for. --Guy Macon (talk) 17:44, 13 December 2018 (UTC)

In the UK, concrete was the surface of choice for motorways (limited access highways) but is being replaced by asphalt because it is so noisy. "Motoring groups say driving on concrete is so unpleasant that some drivers believe there is a fault with their car" - End of the road for concrete on the motorway. Asphalt getting too hot is rarely a problem here though. Alansplodge (talk) 18:24, 13 December 2018 (UTC)

And of course the noise is even more of an issue for the residents, since the road won't be driving away any time soon. Though our article on concrete roads claims there is some kind of "diamond grinding" technique to reduce it, which might be worth investigating further. Wnt (talk) 22:22, 13 December 2018 (UTC)

In parts of the world where it regularly gets below freezing, concrete cracks and spalls due to freezing water and the application of road salt. Some warmer parts of the United States have used concrete roads, but as someone that used to live there, it was not fun to drive on. Sunset Boulevard in Los Angeles was paved with concrete in the 1920s, but since it was such a busy road and concrete takes so long to cure (unlike asphalt, which can be drivable within hours), it wasn't repaved until 2010 and driving on it was always very rough (and the 2010 repaving used asphalt). Similarly, several of the highways in California are concrete, but since concrete is smoother and less water permiable than asphalt, they had to cut "rain grooves" in the roadway to prevent hydroplaning, but these grooves can cause groove wander, where the car tends to wander to follow the grooves. --Ahecht (TALK
PAGE) 19:18, 13 December 2018 (UTC)

I think you've hit it on the head. Laying concrete takes way too long compared with asphalt. That's find when you're building a new highway, but an exasperating inconvenience when you're re-paving. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:55, 14 December 2018 (UTC)

Why are JFK's 8,400 and 10,000 foot runways asphalt while its 12,079 and 14,511 foot runways are concrete? Are the drawbacks of concrete less for (super)jumbo jets than for cars? Sagittarian Milky Way (talk) 19:54, 13 December 2018 (UTC)

Advisory Circular 150/5320-6F, which I found from the airport design and engineering standards website, "provides guidance to the public on the design and evaluation of pavements used by aircraft at civil airports."

The concrete runways are more rigid than the asphalt; this may affect aircraft performance for certain very large aircraft. For KJFK, the airport directory lists the Pavement Classification Number (PCN) for each runway. This number is affected by surface material and many other parameters.

Airport designers usually spend a lot of time studying pavement; there are entire books on how to design and build runways. Here's an entire listing of resources on airport engineering and here's a sub-page just about pavement. Oh, if I could only count the hours I've whiled away, talking pavement with airport engineers,...

From the extraordinarily thorough research paper, Porous Portland Cement Concrete: The State of the Art: "The rising costs for petroleum-based products will make portland cements more competitive with asphalt binders...", and closes by saying "commercial applications of porous concretes should be closely monitored for cost and performance data." So there you have it...

Nimur (talk) 00:43, 14 December 2018 (UTC)

I can remember how surprised I was while being shown round an airport to be told that the concrete was porous! Dmcq (talk) 20:53, 17 December 2018 (UTC)

What building is the most number of rooms long?

Sagittarian Milky Way (talk) 15:26, 13 December 2018 (UTC)

Hilbert's Hotel. DroneB (talk) 16:14, 13 December 2018 (UTC)

What about Earth buildings from the part of spacetime before about 2019? Sagittarian Milky Way (talk) 16:55, 13 December 2018 (UTC)

Do you mean "room" as a unit of linear measurement? Bus stop (talk) 17:33, 13 December 2018 (UTC)

Yes, so a motel 1,000 meters long with rooms every 2 meters would be 500 rooms long and probably only about 2 wide and 1 to a few high. Sagittarian Milky Way (talk) 17:57, 13 December 2018 (UTC)

The great wall of china has an really large number of towers. If you could get an estimate of how many towers and how many rooms in each, it might be the clear winner. --Guy Macon (talk) 18:02, 13 December 2018 (UTC)

It's only sort of a building, vast majority of volume and length was never hollow so you couldn't walk between towers in it, only on it. Must've been a huge amount of man-hours to build though, maybe a room every ~10 meters between towers would've actually been cheaper (but less cannon resistant). Sagittarian Milky Way (talk) 18:26, 13 December 2018 (UTC)

• List of largest buildings
• List of longest buildings

--Guy Macon (talk) 17:51, 13 December 2018 (UTC)

• Prora. 100 hotel suites in each building, plus. Heaviside glow (talk) 20:45, 13 December 2018 (UTC)

MIT's Infinite Corridor runs through several buildings so I don't know if something like that "counts". I'm sure there are longer such corridors but that would expand the possibilities. Mall of America is one building though, I think. 173.228.123.166 (talk) 20:48, 13 December 2018 (UTC)

...or maybe having many small rooms is the key. I wonder how big the largest capsule hotel or self storage unit is? --Guy Macon (talk) 21:42, 13 December 2018 (UTC)

That's true--the definition of 'building' can be complicated. A hospital I visited not too long ago was built in several stages over the course of several decades with the different additions variously abutted to existing structures and/or linked by bridges and underground corridors. The bulk of the facility was tied together by a single long, straight, publicly-accessible hallway below grade; looking on Google Maps it's at least a quarter mile long. Is that one building or a dozen? TenOfAllTrades(talk) 14:32, 14 December 2018 (UTC)

I don't know for sure, but my bet is that whatever building it is is home to a great many shelf companies. Wnt (talk) 22:23, 13 December 2018 (UTC)

The Palace of Versailles has 700 rooms. The Winter Palace in Saint Petersburg "has been calculated to contain... 1,500 rooms" but that sounds like a bit of a guesstimate to me. The "main facade" is 150 m long, but I'm not sure if that includes the two substantial wings which must almost double the frontage. Alansplodge (talk) 11:11, 14 December 2018 (UTC)

THe main block at the Prora Nazi holiday resort was originally 4.5 km long.

And a bit more recently, the main holiday apartment block at Prora, a Nazi holiday resort for the working classes, had a frontage of 4.5 km (2.8 mi) and could accommodate 20,000 people. According to this article, the whole resort had 10,000 rooms, although how many were in the main block is unclear to me. Our article says "all rooms were planned to overlook the sea, while corridors and sanitation are located on the landward side. Each room [was] of 5 metres (16 ft) by 2.5 metres (8.2 ft)".

If only the Nazis had stuck to the package holiday business.... Alansplodge (talk) 14:04, 14 December 2018 (UTC)

...can't they just count the rooms instead of calculating them? shoy (reactions) 14:06, 14 December 2018 (UTC)

You would have thought so. Alansplodge (talk) 16:36, 14 December 2018 (UTC)

One can count them. That's a different question than asking if one did count them. Can is not a synonym of did. --Jayron32 18:01, 14 December 2018 (UTC)

Indeed, but User:Shoy's post was an idiomatic way of asking why they did not. Perhaps they have more pressing problems in Russia. Alansplodge (talk) 17:26, 15 December 2018 (UTC)

Waltham Forest College

So which is the building which has (from a point within it) the greatest distance to an external wall, and what is that distance? Appearances can be deceptive - from the street Waltham Forest College looks like a huge monolith but it's actually built round two courtyards which can be accessed externally. Some apartments in Portugal have a sala interior which is a rather grand name for a small windowless bedroom. The Royal Courts of Justice (which is a building so large that judges have remarked that litigants often get lost) features enclosed open areas to let in daylight (for the purposes of this question the walls to these areas are "external"). 2A00:23C0:7903:B200:6D35:1B0:E2BB:692D (talk) 10:48, 16 December 2018 (UTC)

The Aalsmeer Flower Auction? Sagittarian Milky Way (talk) 14:09, 16 December 2018 (UTC)

Bacitracin

Is the antibiotic bacitracin effective against the bacteria Clostridium tetani aka tetanus?--User777123 (talk) 22:15, 13 December 2018 (UTC)

Tetanus infections are treated with tetanus antitoxin but it's nasty. Normally (at least here), people are supposed to get a tetanus vaccination in grade school, then get a booster shot every 10 years iirc, as routine health maintenance. 173.228.123.166 (talk) 04:51, 14 December 2018 (UTC)

According to this it is effective against other three clostridia species. It is likely to be effective against Clostridium tetani as well but has likely been never tested in this role. On other hand there are reports that some bacteria can be resistant. Ruslik_Zero 14:13, 15 December 2018 (UTC)