Hi, a number of comments have mentioned not explaining what S&C stands for in this video, an over sight on my part! S&C stands for switches and crossings, the parts of the track that make up railway junctions and allow trains to move between different lines. If you want to know more, I have a video explaining what S&C is, which i would encourage you to check out: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-hzhPx4p7vc8.html
I had already figured that out in my own, knowing the British counterpart of what vernacular we speak. On this side of the pond, we call them guard rails.
As an engineer, I know how acronyms can quickly and easily become second nature when talking about a subject. Ive done it many times myself. I find its always useful to define an acronym at the first use in a report or presentation. You never know if there is someone in the audience who hasnt heard it, who learned the concepts in a different language (and thus use different acronyms) or are from a different culture that uses different terms, even if it is in the same language as yours.
In France we also have checkrails (contre-rails) on certain bridges even without curve. I bet it’s for preventing a rare but dramatic consequence of a derailment (falling from the bridge).
Not just France. I've seen a number of Fuehrerstandmitfahrt videos from various places where _every_ RR overpass or bridge has the double check rails, no matter how short the overpass or bridge may be.
I would classify those as Guard rails, although similar to Check rails, they are there in case of derailments to limit the amount of sideways movement and hopefully keep the vehicles on the bridge etc or stop them striking any structures supporting overhead bridges. Wheels do not normally come into contact with them, which does happen with check rails.
It should also be pointed out that, in a curve, that outer wheel climbing the rail, and the inner wheel doing the opposite, serves to make the effective diameter of the outer wheel larger, and the inner wheel smaller, helping to facilitate the negotiation of the curve.
I recall that some British heritage railway centres have had their 9F steam locomotives banned from main-line running by the rail operators because the centre driving wheel, which is flangeless, has been hitting the check rail when using points to cross from one track to another. Thanks for the great presentation.
True but also some check rails are proud (in height) of the running rail. This is why 9F’s are banned off the network due to the derailment risk of the unflanged wheel.
@@thepwayengineer the 9F is a 2-10-0 the centre axle driving wheel was designed to be flangeless to help negotiate curves S&C etc. But they are now banned due to Network Rail using raise check rails in places. Would cause the centre axle to ride up and derail. Go take a peek at Evening Star at York.
On the old Streetcar line in Pittsburgh to Washington PA. The line started as a narrow Guage rail line in 1869. In 1905 the Pittsburgh Railway took over that line and install PA Guage (5 foot 2). Those narrow Guage rails were kepted as a check rail till the line was rebuilt in 1992.
I have also seen greasers on curves in the UK rail network ... specifically on a bend alongside the Norwich "Crown Point" rail depot where I used to work. I don't recall if there were check rails on that section.
I've been a railfan all my life and I've never heard it called a check rail. But then I heard the accent of the narrator - it makes sense. Some call the wooden planks under the rails "sleepers" in the UK. In the US, we call them ties (cross ties). Two people separated by a common language!
@@seanbohannon "Sleeper" is the generic English term for a horizontal beam placed on the surface of the ground to support a structure. A crosstie is a sleeper that crosses the roadbed and ties both rails together. All crossties are sleepers but not all sleepers are crossties. Sleepers are used in all sorts of construction, not just railroads.
I have travelled a lot in trains. Love the sound the of wheels passing over S&Cs, and the sideways jerks you feel. But always wondered from where that high pitched screeching noise was coming from, when the train was going around a bend. Now I know why. Thanks for the beautiful explanation with diagrams. Well done!!
thanks, i've seen these and wonndered what they were. nb, however, you don't define S&C in the video, and as a layman, i've no idea what this abbreviation is.
Very informative. In the US, we call them "guard rails" and they serve the same purpose. There are also special "frogs" (where the rails cross) called "self-guarding frogs" that have a lip on the outer edge that pushes a wheel "from the outside in" to follow the proper course through a frog. Those don't need a "check" or "guard" rail. Any I have ever seen are in slow speed applications like industrial tracks or shop areas but they may be exceptions.
In steam days when the middle drivers were blind or flangeless, self-guarded frogs would deraill the blind wheels as they were wider than the flanged ones. And yes, self-guarded frogs are restricted to slow-speed areas of operation. Most self-guarded frogs are No. 8 or less and are cast manganese steel though I have seen a bolted frog. Due to the design, all of the wheels need to be of the same width, within tolerance, to work as designed.
At least in the US, those are called "guard rails". They interact with wheels only after a derailment -- their purpose is to reduce the risk that a derailed piece of equipment will fall off the structure. They act to keep the truck (or "bogie") vaguely aligned with the rail. In order to fall off or catastrophically interfere with the surrounding structure, the wheel must climb over the guard rail.
@@thomasstambaugh5181thanks for the explanation, I’d seen them on the bridges in RailCowGirl videos from Norway and wondered if that was their purpose.
They are also guard rails in the UK. They have a totally different function to check rails in that they serve to restrain derailed wheel sets from moving too far sideways to try and prevent derailed vehicles hitting bridge parapets or supports. See the accident at Enschede in Germany for example.
I've seen these and figured out the rough idea of why. This video was useful for some specific things I wasn't aware of, especially regarding angle of attack. I am curious why they seem to be common on wooden trestle bridges here in the Western United States, even perfectly straight bridges?
Wondering the same thing. Extra safety to prevent the train from falling off under some rare-but-possible circumstances? Oh, there's a video on it. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2S--oB9WrcM.html
As others have mentioned, these are different, normally having no contact with the wheels, being a safety feature in case of derailment, keeping the wheels close to where they should be.
Why do trains use fixed axles instead of independent wheels on right and left sides? I would think that if the wheels could rotate independently, such as with a car or truck, that would eliminate or reduce greatly the possibility of a wheel derailing in a curve and the horrible squeal that the speed differential causes. We must have the bearing and suspension technology to support the wheels independently right and left.
Im pretty sure a fixed axle actually works with the conical shape of the wheels to keep the train centered on the rails. There are a number of videos that show the physics of this. If nothing else, independent wheels would make the whole setup much more expensive as the suspension systems would have to be much stronger to handle individual wheels instead of solid axles.
@@NicholasIstre You’re right. The exact shape of the cone is important as well - not necessarily a constant angle. The mechanics of a suspension system has it’s part to play as well, as does the angle of the rails themselves, the amount of cant provided on curves, and how much cant deficiency (hence the permitted running speed) on a curve.
Practical Engineering has a great video on this topic. It's based on US rail standards, but the essence is, the crown of the track and the angle of wheels work together to equalize the distance traveled by both sides of the axle. Likely also why the 200m guidance for tight curves as well, since that is the minimum radius that is accounted for in the basic design. Why add complexity to something that works well? Look at what happened in Germany when they tried to make an overly complex wheel for high speed rail.
As a very young man I use to love walking the right of way. I would come across these at merging of tracks and I always thought it just seemed like extra track. Interesting physics involved here. Thank you.
In the UK we call them guard rails! Check rails keep trains on the track, guard rails stop them leaving the railway! Interesting the different uses of names around the world
You did not know there do not exist numbers that are not integers! Hence the radius of a curve clearly must be integer as well. By the same logic, pi equal to 3. \ironyoff
My answer would be that curve radii are always designed in integers, or at the very least are always treated as being in integers. For example, the old Victorian Railways Grades Book, which included the curve radii of all curves (measured in chains i.e. multiples of close to 20 metres) are shown in whole numbers.
Love the videos as they have been very helpful as I work on the railway myself. Is their any way for you to make a video on what different roles on track are what it takes to do those jobs. I'm currently looking to do a Coss course and would like to know what it takes and what I need to know before taking course as I think this would be helpful ahead of time so I'm already familiar with the processes.
Ok. Far more interesting than I expected. 🙂 Now, if I can only figure out what the gauges are on the platform walls down by the tracks I’d die a happy man.
If you're going to educate people you need to do away with Acronyms. S&C needs to be told in full. Don't assume your audience knows this. I am sure if they know S&C then they will know what a check rail is. Railways are full of Acronyms don't use them for educational purposes and different countries use different acronyms.
Acronyms are usually fine so long as you use the full phrase first and then use the acronym with the full phrase used every now and then as a reminder. For example, “…Switching and Crossing, or S&C for short…”
I served my apprenticeship at a UK company who manufactured switches and crossings, finally moving to other engineering challenges in 1986. I worked on several projects involving "swing nose" crossings which technically needed no check rail. Did anything come of swing-nose crossings?
Some of them were, and might still be, in use between London Paddington & Hayes & Harlington, on the higher speed S&C. Without them, there would be too wide a gap for the wheels to pass over. Loads more elsewhere, typically with 70 mph turnouts, like the Wootton Bassett Down Main/Down Badminton junction. So more power operation & detection equipment to maintain etc.
Grew up along the Northeast Corridor. As kids, we used the tracks as highways, (to school, the store...) THese short rails were found along the track but I never paid attention, Now I know what they are.
Something that always amazes me: the Rhätischebahn in Switzerland has some very tight curves (e.g. on the Berninabahn to Tirano), and yet there seem to be no check rails. Any idea why? Checkrails are used quite liberally in hilly areas of South Africa on curves of a wider radius than those of the Berninabahn.
We can see also check rails on bridges, in this case, this is not to avoid to derail, but if this occurs, this third rail help to maintain the train on the railway insteed of falling outof the bridge.
Yes we do! I have found track staff tend to call them switches where as signalling staff tend to refer to them as points If you are interested in switches I do have a video on them: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-EdqNpDn17wI.html
@@pedzsan It is not the same because the shape of a wheel is not symmetric. If there was a high chance of the flange riding up the check rail they could have raised rail to stop that. I think it was not necessary to raise it so they did not because that would increase costs.
@@thepwayengineer I have seen one Fuehrerstandmitfahrt video where a check rail followed the OUTSIDE rail on a curve. Noticed it immediately and thought, "How is THAT supposed to work?"
2:56 I never understood the move to concrete rail ties. Wood has some give in it so it seems like it would be easier on the rails and the train cars. Concrete has no give and it must be both harder on equipment and louder, I would think.
It also lasts longer and is better for high traffic areas. Also, right now, there's an LRT line being installed right by my condo. It uses concrete blocks, which the rails attach to. These blocks are placed on the reinforcing mesh and then concrete poured around them.
I find trains fascinating, but I'm just a casual observer. To think that the outside wheel could climb the track & possibly cause a derailment is scary! On a lighter note, I enjoyed the video, and was intrigued by the optical illusion seen at 5:20 where the train's shadow can be seen on the right-hand side of the bridge =)
Different role on bridges. Those are guard rails (the gap to running rails is larger). Their role is not to prevent derailment but to ensure that the wheel after derailment does not move too far from the railhead to hit the bridge construction or fall over from the bridge.
0:49 Bent rails are standard rail profile, which invalidates what was claimed earlier. Maybe get someone to proofread and edit your stuff before you release it.
G'Day Sir! An Australian here, I seen something like check rails on and under railway bridges, some one said they are AKA *stabiliser rails.* _sorry I can not paste an image, after its RU-vid)_ _As to curves, would check rails reduce the high pitch screaming noise trains make?_ I know it has nothing to do with the gauge of the track as it happens on the Narrow, Standard and Broad gauges!
Q: On many train tressels and bridges there are a *_second_* set of rails about 6-inches inside the main rails which narrow and sometimes almost converge in the center at each end of the bridge. Can you tell us what those are for? Thanks!
S&C is short from Switches and Crossings. Apologies, I should have explain this better in the video If you are interested in switches and crossings I do have a video on the subject: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-EdqNpDn17wI.html
What are the inner rails called (and what do they do) that you see on bridges or trestles? These rails are joined at a point on each end, curving to the center between the traveling rails, and they extend the full length of the bridge. You see them on straight as well as curved sections of track, and the flangeway gap seems wider than on these check rails you are describing.
Everyone has mentioned the use of S&C and yet haven't said what it means. After looking it up it means Switches & Crossings. Please can you add this to the description or pin this comment so others can understand
Why have check rails on one side, sometimes opposite the direction of travel, also why have check rails on both rails of a curve while sometimes only on one side whenever traffic is running on the up and down lines on the same track?
Isnt there also a third common use for check rails: to act as a sort-of guard rail to prevent derailed rolling stock from travelling outside of restricted clearances along tracks? Or do those types of rails have a different name? I know it is common to have extra rails along track with restricted clearance for safety reasons, such as along tunnels, bridges, crossings, or near vital infrastructure (such as support pillars)
I always thought the wheel would try to climb the check rail and cause derailments in configurations like in 5:14, are check rails harder for wheels to climb than normal rails?
Soo … the check rail on the inside of a corner essentially does the same job as a yacht crew leaning out over the exposed hull side of a yacht OR the ‘passenger’ in a racing motorcycle sidecar combination.
Admittedly, this is not a topic I think about much but I am interested to know if anyone even studies whether our existing rail is the best and safest design possible or is this just another "This is the way we do it" mentality that prevails because of cost?🤔
I forget the source, but I read an article on just how much research there was done on this. Over the tears many different profiles have been tried and experimented with. The current profile has been found to be the best and is used universally.
@@thomasstambaugh5181 Actually, yes. In America a guard rail is what this video calls a check rail, and it also stands for the extra rails to prevent derailed trains from leaving the track. Also in America we have a name for the device that allows two rails to cross, we call it a frog.
I think this is a difference in terminology. From some research in the US they are indeed called guard rails, whereas within the UK guard rails are to help stop derailed trains leaving structures etc. Within the UK, fogs are called crossings. Same same but different!
S&C? Oh I see, the definition is in the text below the video. You didn't say in the video. I guessed switch and crossover. A crossing and a crossover are two different things, at least in the US.
I know these as guard rails rather than check rails, and they are there as a mitigation once a train has already derailed! So serving a slightly different function
Good video; other than you explained everything well, yet just referred to "S&C" as a main principal of your explanation. You never clarified what "S&C" is. Abbreviations are good to save effort and time but on the first reference, the abbrieviation should be clarified. [Edit: just read your pinned note. Yep, definitely an oversight!].
Hi, thank you! S&C stands for Switches and Crossings. apologies i should have explained this in the video, an oversight from me. I have a video explaining what S&C is that might be helpful for you: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-hzhPx4p7vc8.html
Completely understand and agree. It is something I will hold my hands up and say I missed when creating this video! I will focus on this when scripting videos going forward. Thank you for watching
