Which arrangement produces less noise, a reversing wye or a balloon loop? Because with a wye, there can be a tremendous clattering as the slack runs in and back out, plus hissing and squealing from the brakes (the latter also varying annoyingly in pitch, because the braking is at very low rotational speeds and any irregularities in the wheels and/or brake shoes will change the pitch of the noise), and with steam or (especially) diesel traction also loud puffing or roaring noise from the engine as the trains restart from a dead stop -- whereas with a balloon loop, these sources of noise are absent, but there can be an ear-splitting screech from the wheels skidding on the rails, and sometimes also loud pops as the wheels break or regain adhesion. So, out of these two methods for turning a train around, which one is less bad in terms of noise pollution (not only the amount of noise in absolute terms, but also perception thereof)? 2601:646:8082:BA0:24C8:7879:FEC5:96E (talk) 03:18, 12 March 2025 (UTC)[reply]

I doubt if there's much to choose between the noise levels, but I'd guess that the duration will be shorter on the loop, since the train just goes continuously round it once, whereas with the Wye (rail) the train has to run out its length on the first 'leg', stop, reverse a long way along the second leg, stop, then proceed back along the third leg, which would surely take more than three times as long as the loop. {The poster formerly known as 87.81.230.195} 94.2.64.108 (talk) 05:36, 12 March 2025 (UTC)[reply]

If it's only about changing direction of travel rather than turning the entire train around, then a passing loop would be a quieter option because you only have to move the locomotive to the other side. --Wrongfilter (talk) 06:17, 12 March 2025 (UTC)[reply]

Why not simply use a turntable, it's space-saving, fast and quiet. Stanleykswong (talk) 19:14, 12 March 2025 (UTC)[reply]

Hm. American freight trains can be more than 2 km long. Try finding a turntable for that. --Wrongfilter (talk) 19:42, 12 March 2025 (UTC)[reply]

American freight trains may be over 2 kilometers long, but I'm sure the locomotives are not.  All you need is a turntable for the locomotive. Stanleykswong (talk) 21:12, 12 March 2025 (UTC)[reply]

Only if it's not bidirectional. Commonly they are, or are grouped so the whole group can go either way. --142.112.222.162 (talk) 21:58, 12 March 2025 (UTC)[reply]

Yes, you're right.  Turntable only works for bidirectional carriages and freight cars. It is not suitable for unidirectional carriages because they only have doors on one side. Stanleykswong (talk) 07:25, 13 March 2025 (UTC)[reply]

I don't know what is meant by 'unidirectional carriages' but if it is locomotives that have a preferred operating direction, or something like a passenger observation car (coach, wagon) with a particular end that should be at the end of the train, turntables are very suitable. Modern 'hood' units can in fact be operated in either direction, but the low or short hood end forward is preferred. The 'grouping' is called 'consisting' and yes, consists can add up to an effectively bidirectional set with a unidirectional locomotive facing 'out' at each end, with either nothing in between, or unidirectional locomotives facing either direction in between, or with 'B units' (without cabs) in between. Hayttom (talk) 16:17, 13 March 2025 (UTC)[reply]

In my experience (which is in Europe), most trains are bidirectional, so there's no need for regular turning (only sometimes to equalise wear). Most trains here are for passengers. Trams may use balloon loops, as it's faster, and people try very hard to make them silent. For goods trains, moving the locomotive to the other end is usually sufficient. But there are cases where it's necessary to turn the entire train around, like when reversing a train with an observation balcony or a car (automobile) train, to make sure the cars face to the platform for easy unloading. Or the route is selected to give an even number of reversals (including the push back to the platform).

How much noise there is from the in and out running of the slack depends on the type of couplings. I understand that American couplings are noisy (and strong) and European couplings are silent (and have no slack). Wheel brakes (acting on the running surface) are noisy, disk brakes are not. The squealing noise from a tight turn results from the flanges touching the rails. Every train wheel has a threshold; only when the radius of curvature drops below the threshold, squealing begins. So this can be eliminated by making the loop large enough. Diesel locomotives make more noise than electrics, in particular when accelerating. Nobody uses steam any more (except some touristy applications).

So we have a lot of variables to consider. PiusImpavidus (talk) 09:12, 12 March 2025 (UTC)[reply]

(edit conflict) In my (subjective) experience the noise of North American trains is very different from European trains, so the answer probably not only depends on engineering details of the arrangement itself, but also on the make of the rolling stock being reversed.  ​‑‑Lambiam 09:21, 12 March 2025 (UTC)[reply]

My impression from OP's description is that they're talking about freight trains. These are of course not bidirectional, but also shouldn't need to be turned around entirely, hence my idea of simply putting the locomotive at the other end (track layout permitting, of course). --Wrongfilter (talk) 10:57, 12 March 2025 (UTC)[reply]

"Freight trains...are of course not bidirectional." Do you mean you can operate a freight train in push mode (rear locomotive) for yard operations, wye, etc. but not for regular mainline service? Are you thinking about a traction or other physics problem, or simply that an engineer in the last car wouldn't be able to see forward well enough to control it safely? DMacks (talk) 01:36, 13 March 2025 (UTC)[reply]

I meant bidirectional for mainline service, do I really have to spell that out? --Wrongfilter (talk) 06:40, 13 March 2025 (UTC)[reply]

Mostly a matter of visibility. For example, the driver must be able to respond to signals before the front of the train reaches them. That may be a bit hard if signals are visible from 300 metres and your train is 1000 metres long and you're driving from the back. In yards where such pushing is used, there may be a shunter on the front of the train, in radio contact with the driver or driving by remote control, but since there's no driving cab, this is illegal at mainline speeds. Alternatively, there may be repeater signals. PiusImpavidus (talk) 10:51, 13 March 2025 (UTC)[reply]

So today Wrongfilter will learn that push-pull trains can easily be done with a simple control car in front rather than a full loco. DMacks (talk) 02:25, 14 March 2025 (UTC)[reply]

Sigh, what is this? We're talking about freight trains, not passenger trains. Neither of these articles mentions freight trains. --Wrongfilter (talk) 06:22, 14 March 2025 (UTC)[reply]

You can make goods trains bidirectional by having a locomotive at both ends. With electrics that's often a waste of resources, but using the less powerful diesels you're likely to need multiple locomotives anyway. Of course, you want some way to remotely control the rear loco from the front one. That either means a data cable running the full length of the train (technically not so hard, but you have to agree on standard cables and connectors and apply those to all wagons on your continent) or some sort of wireless link, with all the difficulties that come with wireless links.

An interesting case of bidirectional goods trains (if I remember every detail correctly...): Some years ago a goods trains operator in the Netherlands wanted to run an intermodal train from Kijfhoek shunting yard to the Bad Bentheim border crossing to Germany. The selected (and shortest) route was Kijfhoek – Rotterdam – Woerden – Utrecht – Amersfoort – Deventer – Hengelo – Bad Bentheim. Go to your favourite map site to check the track layout. This route required reversing at Utrecht, close to the city centre. Authorities, not knowing anything about railways, had forbidden all shunting operations there with trains carrying hazardous materials. Moving a locomotive to the other end of the train is officially a shunting operation and intermodal trains could always carry a container with dangerous chemicals. The solution? The train departed Kijfhoek with a second locomotive, shut down at the rear of the train. At Utrecht, the driver shut down the locomotive at the front, walked to the other end of the train, started the other locomotive and continued his journey.

Some time later the route of the train was revised. Using the detour Woerden – Breukelen – Diemen Zuid – Weesp – Amersfoort, the reversal was gone, but with all those junctions in urban areas, it was probably riskier than the more obvious solution. PiusImpavidus (talk) 11:06, 13 March 2025 (UTC)[reply]

Locomotives are often placed at both ends of long freight trains and also often at a strategic point in between. This is called distributed power and uses wireless links. These have none of the difficulties the previous poster seems to imagine, whereas using a data cable would be far far far harder than they explain or seem to imagine, given that any North American freight car could find itself in the train. The connection that does run car to car is the existing air brake circuit, but this is already built-in whether there is distributed power or not. Hayttom (talk) 16:27, 13 March 2025 (UTC)[reply]

Lac-Mégantic_rail_disaster. 2A00:23C7:E53F:2901:C56C:8909:9074:5E46 (talk) 10:56, 14 March 2025 (UTC)[reply]

I did mention the disadvantage of having to install the cables to all wagons of the continent, right? Passenger trains may use data cables, those American goods trains radio control, most locomotive hauled trains simply put all motive power at the front end. All solutions have significant disadvantages, or everybody would use the same solution. And those very long goods trains with distributed power are very American. PiusImpavidus (talk) 14:51, 17 March 2025 (UTC)[reply]

[un-indent] Actually, I was talking about fictional trains on a railroad which still regularly uses steam traction in revenue service alongside diesel, so merely having the engine run around the train will not be enough (it will still be facing the wrong way, which is inconvenient and may even be unsafe in the case of the big tender engines) -- and there are also questions of canonical accuracy to consider. Specifically, I was asking this question in connection with the spur line serving the Vicarstown Children's Hospital (hence the concern with reducing noise) -- per the lore, the only turntables at Vicarstown are at the Dieselworks, and it makes no sense to put the hospital on the same spur which serves these, given that the entirety of that spur is clearly outside of town to the west, whereas the hospital has to be inside town -- so, the spur serving the hospital has to have some way of turning trains around which is independent of the Dieselworks. But from what I can tell, it appears that the Vicarstown freight yard leads loop completely around the yards in an elliptical spiral (as can be inferred from the way they're shown in the episode where Devious Diesel tricks Rebecca into delivering freight trains to all the wrong places), and that would allow me to place the hospital on the yard leads (this should not hinder road access to it, because the western part of the yard leads is on a viaduct), and incorporate a balloon loop into the yards themselves (similar to the arrangement at Grand Central Station, but smaller and above ground) -- I think this should work fine! What do y'all think? 2601:646:8082:BA0:75FA:A05C:64CE:8D03 (talk) 23:38, 14 March 2025 (UTC)[reply]

I'm aware of a few real-world hospitals with rail access and one even received fuel by rail, the others only passengers. Actually, they all used tramways, not railways. One had coal delivered in a self propelled electric hopper car, moving a few tonnes of coal at a time from the coal depot at a railway station 1.5 km away. The coal tram also served the nearby gas works. It was used 1910–1961.

A spur line would be short, low-speed and have typically short trains. If using steam, that's the domain of tank locomotives, which are equally happy running forward as reverse. In reverse, visibility is usually better. This being fictional, you might encounter the occasional tender locomotive. They can run in reverse too, but with a speed restriction.

If you really want to turn them right there, the normal solution in Europe would be a turntable. Only the locomotive would be turned, then coupled to the other end of the train. North America and Australia preferred triangles (wyes) as they're somewhat cheaper to build and maintain, but they need more land. Or do something crazy: make it a pentagram. A few have actually been built. They're more compact than triangles.

As for noise, I think the balloon loop is best. With a triangle, you have three sets of points and your locomotive (or entire train, if you want to turn all of it) passes twice over each of them. With a loop, there's only one set of points (two resp. zero if the spur is double track). Passing over the points can be a bit noisy. There's also the risk of a noisy wheelslip when starting a steam locomotive and you can build noise barriers along the loop much easier than you can build them along a triangle. But it depends on the details. In fiction, the details may be unspecified. PiusImpavidus (talk) 16:28, 17 March 2025 (UTC)[reply]

Thanks! And yes, given that the engines in T&F seem to be used completely interchangeably without regard to their capabilities (even to the point of doing something so egregious as having Daisy, the diesel railcar (!!!), pull heavy stone cars at the quarry (!!!) -- which, IMO, is worse than having a GNR Stirling 4-2-2 work as an assistant dispatcher), I wouldn't be surprised to see a big tender engine make a delivery to the hospital (and even considering that my project is about serious railroading, not Sharon Miller railroading, it's still very much possible that a freight car for the hospital would be attached to a manifest freight which is heading the right way anyway, and so a tender engine could end up pulling it in that manner!) And yes, I think I'll go with a balloon loop built into the yards Grand Central-style -- like you said, it's less noisy than a wye, especially given that the foolish freight cars (unfitted, loose-coupled wagons) have considerable slack in their couplings (which is what, along with their heavy weight, allows them to bump an engine hard during braking), and so will clatter loudly during any reversing movements! (BTW, I've also considered the issue of air pollution, but given the siting of the hospital, it should be a non-issue -- the hospital will be generally west of the yards, and south-by-southeast of the Dieselworks (I'll just have to make sure it's more south than east of these), so the prevailing winds should blow both the coal smoke from the yards and the diesel exhaust from the Dieselworks well clear of the hospital, most of the time at any rate!) 2601:646:8082:BA0:910C:6AB0:816D:E015 (talk) 06:58, 22 March 2025 (UTC)[reply]