What are the considerations needed to make between choosing a locomotive or MU to power a train?I know passenger trains in Europe tend to be MU but freight is always locomotive hauled.
Freight is usually loco-hauled for convenience and flexibility reasons: one day you could be dragging coal wagons, another you could be pulling oil tankers around. For passenger trains, reliability and track access charges are usually the deciding factors.Regarding reliability: if the engine fails on a loco-hauled train, then it'll block the line for everyone else, in the freezing cold or the baking sun, with the toilet tanks filling up, until it can be rescued by another locomotive. Lose an engine on a DMU and it'll be a minor inconvenience, as there will be two or three others that can pick up the slack: or, EMU stock that was built this century will have redundant duplicates - two pantographs, multiple transformers, and so on.Regarding track access charges: it's like how HGVs pay more road tax than a Fiat 500, because they tear up the roads more. Multiple units are only a little more heavy than a standard unpowered carriage, and the overall weight is neatly spread along the length of the train, so they'll be cheaper to use on the rails than when all the weight is concentrated into a single locomotive.Then there's stuff like, MUs are quick to accelerate because they've a dozen powered axles up and down the train all transmitting the 'oomph' to the rails, rather than just the four on a locomotive, and all those powered axles then make it possible to perform tricks like regenerative braking.And, from an operator's perspective, a MU means you can fit more passengers into the space where a locomotive would be, or a buffet car, or whatever. BR used to use the empty space inside locomotives for parcels and bikes, and in less enlightened times that's how the handicapped had to travel; but these days parcels and bikes aren't profitable compared to bums on seats.
>>1991490This is completely wrong. Locomotives have fewer elements prone to failure than EMUs, and when one EMU element breaks down the whole train stops working, often it won't even be possible to drive a multiple composition with a broken down EMU, maybe it can run under its own power to the next station but more often than not it sti has to be towed by a different EMU or a locomotive. Then once broken down you lose a whole train, while a broken down locomotive can be swapped and the rest of the train stay in use while the loco is repaired.The truth of the matter is EMUs are preferred over locomotive-hauled trains for a sinple reason: shunting. Train companies hate shunting railroad cars, it requires workers, it requires shunting locos, it requires track space for moving cars around, etc.. With freight well fair enough you can't really get around it, but with passenger trains it's avoidable and rail operators will rather deal with the countless drawbacks of EMUs rather than shunt cars around.EMU drawbacks include>when it breaks down the whole train is out of service>all the same, any small breakdown means full EMU out of service, not just the one car>breaks down more easily than a locomotive>awkward space distribution because of mechanical parts having to be fitted>more noise and vibration in passenger compartment>little flexibility, you can only couple together whole EMUs and not single cars (eg. either 8 or 16 cars with no in-between)>you can't combine different trains like maybe through cars or a train section from another country (this is common in Europe) so you still need locos for thattl;dr EMUs are inferior to loco-hauled trains except operations are simplified
>>1991494>when one EMU element breaks down the whole train stops working, often it won't even be possible to drive a multiple composition with a broken down EMU, maybe it can run under its own power to the next stationit stops working altogether but also it can carry on, and bluntly i don't think you know what you're talking about, at all
Each setup has advantages and disadvantages. I think it comes down to what each operator feels better about operating given their own territories and constraints. Personally I'd rather ride behind a conventional locomotive than on a DMU just because the engine noise and vibration is annoying. With EMUs that doesn't matter.>>1991490>all those powered axles then make it possible to perform tricks like regenerative brakingYou can do that and dynamic braking with locomotives as well
>>1991506>You can do that and dynamic braking with locomotives as wellCan you think of any that do?
>>1991494???
>>1991508>Can you think of any that do?I'm not familiar with all locomotives around the world but in North America dynamic braking has been standard on locomotives built in the last 50 years, barring switchers
>>1991506That's one of my main complaints with DMUs.Travelling back home from Nottingham, the Voyagers were loud and rattled when stopped in a station. The HST was silky smooth in comparison with very little noise or vibration.Though a Stadler FLIRT might be a good compromise. It's an EMU that can be converted to a DMU by adding a power pack that has all the diesel engines. That also allows for enough space to lower the floor and have level boarding in the UK.
>>1991582That's an improvement. Can you walk through the power car?
>>1991527Fair enough. Still, I'd expect it's easier to get the motors' tractive effort down to the rails via a dozen powering axles, compared to just four; ditto braking and recovering energy with a dozen axles with motor generators on them.
i mean we joke and all, but 'engine noise and vibration, loco: SOVL, engine noise and vibration, dmu: SOVLLESS' gets tiring when it becomes clear people genuinely believe this
>>1991494>Locomotives have fewer elements prone to failure than EMUs[citation needed]>and when one EMU element breaks down the whole train stops working[citation needed]>breaks down more easily than a locomotive[citation needed]>little flexibility, you can only couple together whole EMUs and not single cars (eg. either 8 or 16 cars with no in-between)this isn't a problem because you don't actually need to hyper-optimise the number of cars>you can't combine different trains like maybe through cars or a train section from another country (this is common in Europe) so you still need locos for thatunless you're running an absolute shitton of through cars this isn't a problem because emus can be made compatible which each otheralso you didn't actually address any of his pro-emu arguments
>>1991605>[citation needed]Not him but you don't make convincing arguments either
>>1991494>>1991494>when it breaks down the whole train is out of serviceNot the case at all.>all the same, any small breakdown means full EMU out of service, not just the one carThe motor car that's effected is the one that is out of operation the train still works, especially with newer EMUs going away from a dedicated motor/trailer set to ".5" motor sets.>breaks down more easily than a locomotiveYou could argue this but new emus are built around redundancy where this isn't an issue.>awkward space distribution because of mechanical parts having to be fittedWhat do you mean I've never had any issues with this unless it was older stock that had to have an ATS cabinet moved inside the train.>more noise and vibration in passenger compartmentOnly in motor cars but it's not even that bad.>little flexibility, you can only couple together whole EMUs and not single cars (eg. either 8 or 16 cars with no in-between)Cool the kururi line runs 1 car dmus in the middle of the day and at rush hour they hook up 3 of those 1 car DMUs together. Keikyu runs 8+4 emus in rush hour and uncouples them at shinagawa until there is enough of them on a storage track and runs them 4+4+4 all abound for different stations. >you can't combine different trains like maybe through cars or a train section from another country (this is common in Europe) so you still need locos for thatJR tokai runs 211,311,313s together in trainsets. Jr Hokkaido even has multiple working on the Kiha 201 dmu with the 731 series emu.
whole load of I Don't Like It So There (crossed arms, pouts) itt
>>1991585Yeah, but it's narrow so you wouldn't want to squeeze through with luggage or in a wheelchair
>>1991646I knew keikyu coupled up their 8+4 trains at kanazawa bunko, makes sense they'd split them apart somewhere too. Do the 12 car trains terminate at shinagawa platform 3? I'd imaging trying to decouple cars on the through tracks would be tricky during peak with them essentially being a metro line. Or maybe they run out of service to the layup tracks above the portal to sengakuji before being broken down?
Imagine shilling for the EMU jew
>>1991646>>when it breaks down the whole train is out of service>Not the case at all.bruh literally no place anywhere ever runs a broken down EMU hooked up to a working one.>The motor car that's effected is the one that is out of operation the train still works, especially with newer EMUs going away from a dedicated motor/trailer set to ".5" motor sets.Or an EMU where one of the motor cars is broken down. It gets sent to the shops right away. So your whole argument is pointless.>You could argue this but new emus are built around redundancy where this isn't an issue."Redundancy" is a strange way of spelling "added expense">>awkward space distribution because of mechanical parts having to be fitted>What do you mean I've never had any issues with this unless it was older stock that had to have an ATS cabinet moved inside the train.The only EMUs with level floors are high-floor ones. Low-floor ones need to make space at the end of the cars for the motors and all that.Double-decker EMUs will have long, narrow corridors at the end of the cars where the mechanical elements are housed.>>more noise and vibration in passenger compartment>Only in motor cars but it's not even that bad. You said yourself that EMUs are moving away from dedicated motor-trailer sets>Cool the kururi line runs 1 car dmus in the middle of the day and at rush hour they hook up 3 of thoseThis only works in a extremely low-capacity situation, as hooking up a bunch of small EMUs/DMUs ends up simply being way more expensive and requiring more maintenance than one loco and a bunch of cars.tl;dr you're wrong and I am right.
>>1991483Locomotive for long distance train, EMU for commuter train and HSR.
>>1991735>bruh literally no place anywhere ever runs a broken down EMU hooked up to a working one.and where are these places that are constantly swapping out failing loco-hauled passenger cars?>"Redundancy" is a strange way of spelling "added expense"do you think choosing multiple units instead of locomotives is the financially wrong choice to make>This only works in a extremely low-capacity situation, as hooking up a bunch of small EMUs/DMUs ends up simply being way more expensive and requiring more maintenance than one loco and a bunch of cars.he literally gave an example of 4-car units being used and split on a busy commuter line>as hooking up a bunch of small EMUs/DMUs ends up simply being way more expensive and requiring more maintenance than one loco and a bunch of cars.again, where are these places that are constantly removing and adding cars to meet demand?
>>1991764>and where are these places that are constantly swapping out failing loco-hauled passenger cars?Locos don't fail because they're built better. After all, they're purely tractive vehicles, not a combination of tractive and passenger car.>do you think choosing multiple units instead of locomotives is the financially wrong choice to makeDepends. But I'm ok with spending more on railways if it creates local jobs in operations rather than in manufacturing train parts in Chyna or something.>he literally gave an example of 4-car units being used and split on a busy commuter lineYou didn't get my point. The smaller your trains, the more flexibility but the more expensive overall. Two 4-car EMUs are more expensive than one 8-car EMU. That's the point. In Switzerland they're using 8-Car EMUs now for some trains. Meaning composition is 8 or 16 cars. Limited flexibility. Having 4-car EMUs would increase expense, and in the end you'd be shunting almost as much as loco+cars.>again, where are these places that are constantly removing and adding cars to meet demand?Switzerland. They used to adjust compositions all the time for different lines, with trains anywhere from 5 or 6 cars (I even remember riding a 3-car train once) up to 16 cars, either single deck or double deck. They still do this, just less so. They'd even set up longer trains for holidays and such. Or add a few extra cars during peak hours. They could also add or remove restaurant cars. Now the EMUs will often run with a closed restaurant car when it's not operational on that route. I'm not even saying that EMUs don't have their use, they're good for local and commuter trains because of better acceleration. They're just not better for long distance trains. Trying to argue reliability is the dumbest argument ever. There has never been a train in Switzerland so unreliable as the new flagship long-distance EMUs. The old locos from the 60s have better reliability and are even used on commuter trains.
>>1991740This
>>1991781>Locos don't fail because they're built betteroh ok well if we're just declaring things as though they're objective universal facts,
>>1991483Freight traffic is almost entirely loco-hauled as it has been proven time and time again that it is best to move tonnage at moderate speeds and loaded to the brim. There were some attempts of making freight EMUs, but all were unsuccessful. Which, of course, makes sense - as it is better to have a strong lead vehicle and lightweight ( relatively ) freight cars. You both get flexibility and only once maintenance heavy vehicle.For passenger trains - except for some few exceptions - lightweight, distributed powered MUs are superior.1. Locomotive does not take space at a station. EU stations are, increasingly, built for 200 or 400m long trains and it is best to have all that 400m available for boarding.2. Distributed power allows for higher acceleration. In a highly trafficked commuter system, this might save you 5 seconds at every start/stop, but that adds up quickly if you have 40 stops on a line, or need to stop every mile or so.3. Maintenance costs depend on speed and axle load - so you want your 200-300km/h trains to be as lightweight as possible. For this reason, french LGVs are limited to 17t and Japanese go as low as, if I recall, 12t on Shinkansen lines. This is expressed in infrastructure access costs, where it is relevant. In EU running an emu with 12 ton axle load will be cheaper than running a train of equivalent weight, but with a 22,5t axle load loco at the front.4. Plain physics - while in fright trains you can get a 4:1 net-to-tare ratio, it is much worse for passenger trains. This is especially bad for shorter trains - as two double-decker car train weighs just a smidge more than a locomotive pulling them. You can get the same capacity of an emu with half the weight....
>>1991939Locomotive pulled trains only make sense for:1. Night trains, where it is common to mix/match/shunt trains midway to allow more connectivity and traffic is not speed sensitive.2. When you need to run longer trains on non-electrified territory. Larger diesel engines are cheaper to maintain and operate than an equivalent power in smaller ones.3. You run really, really long trains - like India-level 10-15 car ones, and you already have a bunch of wagons to do it.Also - the flexibility of loco-hauled trains is grossly overstated. Firstly - it is rarely needed. Secondly - with a fleet of EMUs of varying lengths ( pic rel - PESA elf series can be had from 2 to 6 section versions ) you can respond to traffic changes just as well and day-to-day savings from running EMU will overwhelm benefits of this mythical 'flexibility'. There is a reason why MU took over. People who run passenger trains are not dumb.
>>1991781>Depends. But I'm ok with spending more on railways if it creates local jobs in operations rather than in manufacturing train parts in Chyna or something.well if you're pro-make-work jobs i don't see why you're complaining about lack of flexibility with emus>Switzerland. They used to adjust compositions all the time for different lines, with trains anywhere from 5 or 6 cars (I even remember riding a 3-car train once) up to 16 cars, either single deck or double deck. They still do this, just less so. They'd even set up longer trains for holidays and such. Or add a few extra cars during peak hours. They could also add or remove restaurant cars. Now the EMUs will often run with a closed restaurant car when it's not operational on that route. And what's the problem with running with extra cars?
>>1991734They're pretty good most of the time, the experience is far better than DMUs.>>1991964>And what's the problem with running with extra cars?No problem when they're running and providing needed capacity. The issue is the extra money spent on maintenance and storage. There's a point where the benefit of spare capacity is outweighed by the increasing cost. Admittedly it's lower with coaches than EMUs but it's still there.
>>1991995Metra runs 6+ car trains nearly all the time but only opens the first 2 or 4 cars to save on conductors. I guess yard operations are more expensive than the added wear on the cars. I'm not sure when they actually use all the cars because even during festival weekends they don't use the full train length.
>>1991995but the additional cost of having a car running in a train as opposed to being stored somewhere is basically nil>>1992021>Metra runs 6+ car trains nearly all the time but only opens the first 2 or 4 cars to save on conductorsthat's because american commuter rail has insane staff bloat
Why aren't Jacobs bogies more of a thing with coaches? I can only think of the TGV as an example of a locomotive + articulated coach set. They seem to be a neat idea, you can save weight and increase capacity for a given train length, lots of EMUs (like pic related) use the configuration.I understand that freight wagons might have issues due to axle loading limits, but coaches are far lighter.>>1992021That's weird, maybe they're in a coach 'set' of 6 that are semi-permanently coupled together?I'd imagine that disconnecting & reconnecting the cab car would be a pain so it's just easier.>>1992150It's wasted energy and there's still wear and tear to consider. Though as you say that might be negligible.
>>1992346>Jacobs bogiesmain downside is that cars sharing a bogie are a bitch to seperate, while the whole point of using sperate cars instead of an integrated multiple-unit design is to be flexible in their combination.Btw, I've seen similar designs (not sure if technically a jacobs bogie or if there's special terms for it) in car-transporters and container train cars, making two-car consists with 3 or 6 axles respectively.
>>1992370I've always heard them referred to simply as articulated cars, jacobs bogie I only hear in reference to passenger equipment. Articulated autoracks are two cars, articulated well cars can be up to five cars, at least in US. 3 and 5 car articulated well cars are very common. I don't see it as much with autoracks.
>>1992346>Why aren't Jacobs bogies more of a thing with coaches?When going through the trouble of Jacob's bogies, it makes no sense to have them on 'dumb' coaches. If you want to keep the axle load in check, the middle sections will get about half the capacity of a full coach - or even less when vestibules are considered. Jacobs bogies are also troublesome to rearrange the train, if it's not an EMU, then why limit the inherent flexibility of the wagon consist?This is why they are popular on EMUS, but not traditional coaches.However, this does not mean there weren't any. A famous example was British Silver Jubilee coaches originally pulled by A4 Pacifics. Pic rel is a German-made four-car set of Polish railway's double deckers which were phased out a few years ago. Those have three axle Jacobs bogies and were being used as two, three and four car sets. Romania, I think still uses these.
>>1992370>>1992472I'm only asking as it seems like most passenger trans are made of coach sets where you have a number of them coupled together for a long period.The axle loading doesn't shoot up nearly as fast as you might think, a coach is an air-filled with some seats, racks, etc inside. Also, each section in an articulated set is shorter to reduce overhang inside the curves, but there's a reduction in the number of bogies over the whole train length.The overall weight of the train goes down too, as each bogie is heavy. Maybe ~6 tons each for a lightweight design, which adds up. E.g. for a train of 8 coaches that could be a full coach's weight.I get that this is probably more of a consideration where acceleration/ high speed performance is needed. As you say, for Amtrak and other long distance/slower services the consideration changes to reliability and easy maintenance.
