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	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=3105:_Interoperability&amp;diff=380207</id>
		<title>3105: Interoperability</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=3105:_Interoperability&amp;diff=380207"/>
				<updated>2025-06-23T00:13:50Z</updated>
		
		<summary type="html">&lt;p&gt;Optimore: /* Explanation */ There are a lot of engineering issues with actually trying to do this- to the point it seems likely Black Hat is really trying to cause chaos rather than merely inconvenience.&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;{{comic&lt;br /&gt;
| number    = 3105&lt;br /&gt;
| date      = June 20, 2025&lt;br /&gt;
| title     = Interoperability&lt;br /&gt;
| image     = interoperability_2x.png&lt;br /&gt;
| imagesize = 740x269px&lt;br /&gt;
| noexpand  = true&lt;br /&gt;
| titletext = We're getting a lot of complaints from commuters who were routed onto a coaster, but the theme park patrons who spent hours stuck on an intercity line are also not happy.&lt;br /&gt;
}}&lt;br /&gt;
&lt;br /&gt;
==Explanation==&lt;br /&gt;
{{incomplete|This page was created by a LOST ROLLER COASTER RIDER. Don't remove this notice too soon.}}&lt;br /&gt;
&lt;br /&gt;
[[Black Hat]] gives a presentation regarding the existence of two standards: rail systems predominantly use the {{w|Standard-gauge railway|standard gauge}} of 143.5cm (or the virtually identical 4 ft 8½ in, in the US), and associated {{w|Rapid transit|subway systems}} and their cars are built to match this standard. Meanwhile 'many' {{w|roller coaster}} tracks, and their cars, are said to use a 110cm gauge. The two standards are not compatible, without {{w|Dual gauge|some additional engineering}}; subway cars could not travel on roller coaster tracks, and vice versa, even assuming you solved {{w|List of steepest gradients on adhesion railways|other issues}}.&lt;br /&gt;
&lt;br /&gt;
However, Black Hat has professed to make changes to roller coasters such that they now conform to the subway standard (i.e. 143.5cm gauge). This seemingly is Phase One of a plan, and while no details of Phase Two are forthcoming, it may superficially allow subway cars to ride on roller coaster tracks ''and/or'' roller coaster cars to ride through subway systems, apparently in the name of {{w|interoperability}} and compatibility. This would have the advantage of letting many more people ride a roller coaster at the same time and granting subways easier access to additional {{w|rolling stock}}. However, the lack of interoperability in this case is by design, since if a railroad and a roller coaster track were ever to be accidentally connected, cars routed to the other system would simply derail due to the vast differences in design between the two aside from the difference in gauge.&lt;br /&gt;
&lt;br /&gt;
[[Cueball]] and [[Hairbun]] are the apparently unwitting audience to Black Hat's presentation, and one of them (from off-panel) objects by stating that interoperability isn't ''necessarily'' a good thing, recognising where the plan is heading. Black Hat suggests that it would be fine as long as passengers of such interoperable systems listened to the destination announcement, indicating that he does indeed plan to connect the two which may lead to various unexpected surprises.&lt;br /&gt;
&lt;br /&gt;
In reality, the engineering challenges of actually doing such a thing would be almost impossible to surmount. This is because, despite the superficial similarities of rollercoasters and subway trains as vehicles that run on rails, the two are used for completely different purposes and have vastly different designs (i.e. subways using {{w|Train Wheel|sets of flanged steel wheels on top of the track}} vs. coasters using {{w|Roller coaster wheel assembly|polyurethane rollers above, below, and to the sides of the track}}). Attempting to modify one system for compatibility with the other would likely lead to loss of capability in its original role and/or complete ''inoperability'' as neither system is capable of operating within two mutually exclusive sets of design constraints. Despite Black Hat’s claims of the importance of compatibility and interoperability, it seems clear that his actual intentions are simply to compromise ''both'' systems through a nonsensical and likely illegal attempt at connecting them together. &lt;br /&gt;
&lt;br /&gt;
For instance, roller coaster trains feature wheels that run under the rails- “up-stop” wheels- that prevent the train from lifting off the track during negative G’s. As subway tracks are fixed to the ground and have no underside clearance, a roller coaster train would simply slam its up-stop wheels into the ground and stop immediately if transferred onto a subway track. However, removing the upstop wheels in an attempt at interoperability would leave the train unable to safely complete its original roller coaster route.&lt;br /&gt;
&lt;br /&gt;
In some parts of the world, the lack of interoperability between different rail networks does cause issues.  For example, in Australia there are currently [[https://www.lexology.com/library/detail.aspx?g=fcd3656b-c5c4-4513-ae29-3c0c5dc82781 three different rail gauges in usage]].  As a result, passengers or goods travelling from Melbourne to Sydney to Brisbane could theoretically have to switch twice between rolling stock on different sized rails to complete the journey.&lt;br /&gt;
&lt;br /&gt;
The title text confirms that ''both'' reapplications of railcars are being used, the engineering problems having apparently been solved in Phase 2: there are commuters who find themselves traveling upon a coaster, who may not reach their intended destination or suffer unexpected {{w|g-force}}, and there are roller coaster riders who find themselves traveling down a subway line, a much longer and more boring ride. Furthermore, those expecting to experience a theme park ride were probably ''expecting'' exciting g-forces, and also to shortly return to no more than a short walk away from where they initially boarded, but find themselves outside the theme park, spending hours on an intercity line. Also, a subway line would also not usually be expected to travel between cities, but at least the interoperability of subway rail and wider rail systems ''might'' be expected, so long as the {{w|Third rail|appropriate infrastructure}} and track links can be made compatible. The roller coaster cars may also {{w|Physics of roller coasters#Energy|come to a stop}} if the cars aren't self-propelled, which may lead to the patrons being unable to leave the cars safely and will lead to the blockage of the route.&lt;br /&gt;
&lt;br /&gt;
Alternatively, it may be that Black Hat intentionally did ''not'' solve the additional obstacles to interoperability, and the complaints are coming from commuters who experienced violent derailment of their subway trains upon entering roller coaster track and coaster riders who became stuck on rail lines due to incompatibility between the coaster wheels and subway rails causing them to suddenly stop.&lt;br /&gt;
&lt;br /&gt;
==Transcript==&lt;br /&gt;
{{incomplete transcript|Don't remove this notice too soon.}}&lt;br /&gt;
: [A close-up shot of Black Hat from the shoulders up]&lt;br /&gt;
: Black Hat: Compatibility and interoperability are so important.&lt;br /&gt;
&lt;br /&gt;
: [A zoom out reveals that Black Hat is standing in front of and pointing at a diagram showing a commuter subway car and a roller coaster car, and the tracks they both run on. Standing next to him are Cueball and Hairbun]&lt;br /&gt;
: Black Hat: For example, most subway rails are 143.5 cm apart. But many roller coasters use a narrower 110 cm gauge.&lt;br /&gt;
&lt;br /&gt;
: [This panel shows only Black Hat]&lt;br /&gt;
: Black Hat: For the last few years, our company has been quietly retrofitting roller coasters to use 143.5 cm tracks.&lt;br /&gt;
&lt;br /&gt;
: [Black Hat now has his fists raised]&lt;br /&gt;
: Black Hat: Soon, we can begin phase 2.&lt;br /&gt;
: Voice from off-panel: Maybe interoperability is actually bad.&lt;br /&gt;
: Black Hat: If you listen to the destination announcement while boarding, you'll be fine.&lt;br /&gt;
{{comic discussion}}&amp;lt;noinclude&amp;gt;&lt;br /&gt;
[[Category: Comics featuring Cueball]]&lt;br /&gt;
[[Category: Comics featuring Black Hat]]&lt;br /&gt;
[[Category: Comics featuring Hairbun]]&lt;/div&gt;</summary>
		<author><name>Optimore</name></author>	</entry>

	<entry>
		<id>https://www.explainxkcd.com/wiki/index.php?title=Talk:3105:_Interoperability&amp;diff=380081</id>
		<title>Talk:3105: Interoperability</title>
		<link rel="alternate" type="text/html" href="https://www.explainxkcd.com/wiki/index.php?title=Talk:3105:_Interoperability&amp;diff=380081"/>
				<updated>2025-06-21T07:07:39Z</updated>
		
		<summary type="html">&lt;p&gt;Optimore: Nerd talks about engineering problems&lt;/p&gt;
&lt;hr /&gt;
&lt;div&gt;&amp;lt;!-- Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom. --&amp;gt;&lt;br /&gt;
Well, it is not interoperability that would be the potential problem, but potential interconnectedness. Some systems are just not meant to be connected to the rest of the network`21:48, 20 June 2025 (UTC)&lt;br /&gt;
&lt;br /&gt;
There will be more interoperability concerns than the track gauge. Such as the up stop wheels. And side wheels. [[User:Henke37|Henke37]] ([[User talk:Henke37|talk]]) 21:55, 20 June 2025 (UTC)&lt;br /&gt;
&lt;br /&gt;
&amp;gt; &amp;quot;''two standards: US rail systems predominantly have a 143.5cm gauge''&amp;quot; Why cite &amp;quot;US&amp;quot;? 4 ft 8+1⁄2 in was developed in England. The US got confused and Abe Lincoln is credited with ordering first 5' (won't work) then 4 ft 8+1⁄2 in (most US rails were so close to 4'8.5&amp;quot; that they mostly changed in a weekend). Rest of world used UK or US machines, or copied them, with the main exceptions fading away over a century. (Well, Australia was still jacking cars mid-route when I was young.) &lt;br /&gt;
https://en.wikipedia.org/wiki/Track_gauge#%22Standard%22_gauge_appears&lt;br /&gt;
The width of two horses' asses, a Roman chariot, is often cited as if pre-industrial mechanics standardized.&lt;br /&gt;
--[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 05:39, 21 June 2025 (UTC)&lt;br /&gt;
&lt;br /&gt;
As a coaster and rail nerd, it's basically impossible to actually do this (and not just for the obvious safety problems). The engineering between a rail line and a coaster track (and the wheels that run on them) are completely different. Rails have an I-beam shaped cross section and are fixed to the ground, and trains use steel wheels that have flanges on the inner side keeping the cars from running off the track. Steel roller coaster tracks have a circular cross section and the cars have wheels that are (usually) polyurethane, with additional sets of wheels on the side and running under the track (upstop wheels) keeping them from flying off when pulling Gs. Even if you corrected for any track spacing and shape difference somehow, a roller coaster train would immediately slam its upstop wheels into the ground and stop if you tried to transfer it onto a regular grounded rail line. Likewise, since roller coasters don't have flanges, they often have support beams crossing the inner space between the rails, so a train trying to navigate a coaster track would slam its flanges into the support beams and either immediately derail or else start shearing the entire track apart, if it didn't already derail from the wheel flanges not having any grip on the circular coaster rails. [[User:Optimore|Optimore]] ([[User talk:Optimore|talk]]) 07:07, 21 June 2025 (UTC)&lt;/div&gt;</summary>
		<author><name>Optimore</name></author>	</entry>

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