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Author Topic: Electric convoys enter non-electrified track with diesel locomotives  (Read 2542 times)

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Offline THLeaderH jp

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Hello, everyone.

In current simutrans, an electric convoy cannot enter non-electrified track even when it contains diesel locomotives. However, there are some cases in the real world that an electric convoy is towed by a non-electric locomotive and enters non-electrified track. So, why don't we allow an electric convoy with non-electric locomotives to enter non-electrified track with the power of the non-electric locomotives?

Offline Václav

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #1 on: July 15, 2019, 10:20:50 AM »
I tink that this was discussed at least once some time ago. I am not sure what situation is in extended release (formerly experimental) but in standard it is not available and if I remember correctly, nothing such was planned.

I found it - here, in topic Hybrid trains.
« Last Edit: July 15, 2019, 10:31:07 AM by Václav »

Offline THLeaderH jp

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #2 on: July 15, 2019, 10:33:52 AM »
This request has more meaning when it comes with my convoy coupling project. In the real world, an electric train is often towed temporarily by a diesel locomotive in non-electrified sections. If simutrans allows electric convoy to enter non-electrified track with non-electric locomotives, this operation is possible and it becomes a great reason to do a convoy coupling. (a coupling of a diesel locomotive and an electric train.)

Offline Ranran jp

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #3 on: July 15, 2019, 11:59:16 AM »
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However, there are some cases in the real world that an electric convoy is towed by a non-electric locomotive and enters non-electrified track.
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In the real world, an electric train is often towed temporarily by a diesel locomotive in non-electrified sections.
I think these expression is misleading.
(I think that an "electric convoy" you say refers to EMU when applying the case of Japan.)
No matter how much Japan is a hentai country it is a very special case.
There are many conditions that are not sufficient just to connect EMU and a diesel locomotive.
In that case, it is no exaggeration to say that there are few such cases.
« Last Edit: July 15, 2019, 05:11:17 PM by Ranran »

Offline Leartin at

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #4 on: July 15, 2019, 12:01:33 PM »
I suppose the issue is routing, though I can't know for sure.

See, the rule right now is simple: "Electric units can only use electrified tracks". And that's not exactly realistic, but close enough. If you would instead say "Electric units only work as locos on electrified tracks" you open a can of worms. Because that would mean a train that has only an electric locomotive on unelectrified track would be equal to a train with no locomotive at all. However, trains with no locomotive are not quite sitting ducks - instead, they still move at 1 km/h. The only thing stopping you from having all your trains without locomotives is the depot not allowing you to send out a train without loco, but once they are out (eg. by loading without the loco-object) those 1km/h trains have no issue going everywhere. So if electrict vehicles would work the same, they could route over unelectrified tracks if nothing else is available. Nobody wants that.

I'm sure there are some solutions to this, but even before you think about how to program it, thinking about how it should work in various situations might give you a headache.

Offline THLeaderH jp

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #5 on: July 15, 2019, 12:20:38 PM »
The routing condition is simple: If there is a non-electric locomotive in the convoy, is_electric is false. Otherwise, is_electric is true. In route search, only convoy that has at least one non-electric locomotive is allowed to take a route which has non-electrified section. If a convoy with only electric locomotives tries to calculate route and there are no choice but to pass non-electrified section, the route search result must be no_route, that is same as current simutrans. This prevents electric convoys from moving at 1km/h in non-electrified section because a convoy cannot be disassembled outside a depot.
« Last Edit: July 15, 2019, 12:35:02 PM by THLeaderH »

Offline prissi

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #6 on: July 15, 2019, 02:02:24 PM »
There has to be a special routing penalty, and not routing the shortest route which would be 95% non-electric. Also in real world, usually the engine is exchanged unless there are special construction works. Dual traction exist when the electric is just an extra push for a slope (that exist still in very few places, but the electric engine will uncouple after the slope). Because engines are heavy, and usually you do not want to haul them needlessly. Also they must be remotely controlled, if diesel and electric should work together.

Offline Ters

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #7 on: July 15, 2019, 07:29:44 PM »
There is also the "last-mile" locomotives as well, which I've only seen modern examples of, so the concept might be new. They are primarily electric locomotives, but have a diesel engine to take them down a non-electrified siding or short branch. It is to avoid having to switch to a different diesel locomotive, typically a smaller shunting locomotive, which most likely needs its own crew. The locomotive is weaker running on diesel, possibly more expensive, and the small fuel tank gives short range. All these three concepts are absent in Simutrans, so at the moment, they would be indistinguishable from a pure diesel locomotive. Adding these concepts adds more complexity to what is quite a complex game already.

The only case of contemporary train merging I am used with, actually involved merging a diesel and electric train. However, the merged train ran on an electrified line. The electric locomotive was also by far the stronger of the two, by factor of over three. I think that usually, the diesel locomotive was left behind during the merge. The only reason it might come along, was probably to get to the main depot for maintenance. Sometimes, an electric locomotive would hitch a ride with the diesel, but I don't think that was part of normal operations. I don't remember seeing it myself, only a photo by someone else. It might just be the easiest way to get the electric locomotive from A to B, compared to the longer, busier electric main lines.

Also they must be remotely controlled, if diesel and electric should work together.
You can just have two crews. Although it requires delicate coordination between the crews, I seem to remember reading about it being done. And that was pretty much the only way to use two steam locomotives together.

Offline Václav

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #8 on: July 15, 2019, 08:26:50 PM »
Also in real world, usually the engine is exchanged unless there are special construction works.
Yeah, yeah. Related to knowledge from the Czech republic, electric locomotives are often capable to go faster and pull more than diesel ones. And also, they may have greater weight.

And specially this electric/diesel pair of locomotives is in service on line from Prague to Trutnov via Hradec Králové - with locomotives change in Hradec Králové. From Prague to Hradec Králové (and back) goes mostly locomotive class 163 (or sometimes class 150). From Hradec Králové to Trutnov (and back) goes class 752,6 (or 753).

Electric locomotive known as class 163 or class 163
Max. speed: 120 km/h (140 km/h)
Service weight: 85 tons
Max. pull power: 285 or 300 kN

Electric locomotive known as class 150
Max. speed: 140 km/h
Service weight: 82,4 tons
Max. pull power: 227 kN

Diesel locomotive known as class 752.6 or class 753:
Max. speed: 100 km/h
Service weight: 72 tons (76,8 tons)
Max. pull power: 218 kN (215 kN)

But there are more lines with locomotives exchange - I know about at least two another.

For example, from Brno to Plzeň via Jihlava and České Budějovice. It is very long line where are two locomotives exchanges. In direction from Brno it is from diesel to electric in Jihlava and from electric to electric in České Budějovice. But the second exchange is done for simple reason - train goes to and from České Budějovice by deadlock (similar it is to and from Jihlava - but there is also change to and from electric). But there are used else electric locomotives because catenary is supplied by else system.

On unelectrified tracks, electric locomotive could be only dead weight to pull for diesel ones - meanwhile, on electrified tracks, diesel locomotives could help to electric one.

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Dual traction exist when the electric is just an extra push for a slope (that exist still in very few places, but the electric engine will uncouple after the slope).
I beg your pardon, I don't know what situation is in your country, but I have not seen such combination of locomotives in service. Only multiple diesel or multiple electric. Even if I have already seen train with electric and diesel locomotives, those trains really used locomotives of only one traction - and locomotives of other traction were only transferred elsewhere.

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Because engines are heavy, and usually you do not want to haul them needlessly.
See locomotives comparison written above.

And if I take weight of one passenger car about 40 tons (weight of empty car ABpee347; fully loaded it has 48 tons; else cars may have else weight) and five cars in train (the most common number cars in trains pulled by diesel locomotives), then one electric locomotive takes space of two passenger cars.

In case of freight cars it may be many more, because many empty freight cars are quite light in comparison in empty passenger cars. But fully loaded freight cars may have greater weight.

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Also they must be remotely controlled, if diesel and electric should work together.
And here is the greatest problem, I think. But problem may be (sometimes) in multiple traction of locomotives of the same type, and also even in one class.

For example, only some locomotives of class 752,6 or 753 were equipped by remote control. And so you can see two locomotives looking like other ones of the same class - and meanwhile one locomotive may be used in push/pull train, else locomotive not.

But this may be ignored in game.

Offline ACarlotti

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #9 on: July 15, 2019, 10:59:11 PM »
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Dual traction exist when the electric is just an extra push for a slope (that exist still in very few places, but the electric engine will uncouple after the slope).
I beg your pardon, I don't know what situation is in your country, but I have not seen such combination of locomotives in service. Only multiple diesel or multiple electric. Even if I have already seen train with electric and diesel locomotives, those trains really used locomotives of only one traction - and locomotives of other traction were only transferred elsewhere.
I am not aware of this situation existing in the UK yet, but there have been suggestions to introduce it in the southwest. The new trains on the Paddington to Penzance are hybrid multiple unit trains, and will run under electric power between London Paddington and Newbury, and then on diesel power thereafter. The line through Devon/Cornwall has some notoriously steep gradients, and since a significant number of trains using the line will now have electric capabilities, it has been proposed that electrifying the steep (uphill) gradients could provide noticeable benefits to journey times at lower cost than full electrification would entail.

Offline Ranran jp

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #10 on: July 16, 2019, 08:47:21 AM »
It should be noted that what THLeaderH is saying and what others are saying is a completely different case.
What THLeaderH says is that diesel locomotive pulls EMU. Diesel locomotive (and generator vehicle) is added just before entering the non-electrified section to pull EMU. Then EMU can enter the non-electrified section. (Then EMU stops all motors.)
I think other people are talking about dual-mode or bi-mode and Prissi is talking about support locomotives for the slopes.

That (diesel locomotive pulls EMU) is a very rare example in Japan, just allowing it will break the game balance.
On the other hand, nowadays there are many examples of dual-mode vehicles.
I think in both cases the problem is in running costs rather than route searching. Because EMU needs a large investment in electrification originally, it should be characterized as a low running cost instead.
This can be considered separately from convoy coupling.
For dual-mode vehicles, different running costs need to be set in the electrification mode and the non-electrification mode.

And what makes THLeaderH's case special is that EMU shuts down the motor on non-electrified sections. That is, EMU changes to just a coach and the value of power differs in electrification mode and non electrification mode. (Implementing the function itself is not difficult. However, you will need to support players avoid being confused.)

Many bi-mode vehicles generate electricity with the engine in non-electrified sections or rotate the motor with a battery. In this case, the output of the motor does not change.
In the case of battery, runningcost is the same as electrification section, but it is impossible to run only a certain distance.
The output may change in the case of the type running on the non-electrified section with the engine. But it will not be 0. (If this goes to 0, the possibility of deadlocks rises. And it may not be allowed unless there is a convoy coupling outside the depot feature.)

Another point is that this may be a small issue, but it is a graphic issue.
Yes, bi-mode vehicles do not leave pantographs elevated in non-electrified sections.
You may also need to switch the display of the smoke.

From the above, I think that the implementation of bi-mode vehicle requires a switch of runningcost, power, gear, and graphics.

In a discussion ten years ago, James has decided to forgo the bi-mode implementation because it has determined that the effort is not worth it. However, bi-mode vehicles are increasing in recent years and it would be great if implemented. ;)

Offline Leartin at

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #11 on: July 16, 2019, 10:09:26 AM »
The routing condition is simple: If there is a non-electric locomotive in the convoy, is_electric is false. Otherwise, is_electric is true. In route search, only convoy that has at least one non-electric locomotive is allowed to take a route which has non-electrified section.
Say there are two parallel tracks, one electrified, one isn't. The electrified track is one tile longer. If you only check whether a convoy is allowed to go there, a mixed convoy would always route via the unelectrified track, even though that means the electric unit is merely baggage. This would be infuriating.

A routing penalty, as prissi suggests, might help. Though it probably ends up meaning that no unelectrified track is used unless absolutely necessary.

If a convoy with only electric locomotives tries to calculate route and there are no choice but to pass non-electrified section, the route search result must be no_route, that is same as current simutrans. This prevents electric convoys from moving at 1km/h in non-electrified section because a convoy cannot be disassembled outside a depot.
Except your convoy coupling patch kind of is all about assembling and disassembling outside a depot. What happens if an electric unit and a diesel locomotive merge, reach their next destination which happens to be unelectrified, and split there? You'd have to check the splitting point before they even merge, many stations in advance. Possible, I'm sure, but not... elegant.

One could handle it from a completely different angle. Start by changing what happens to convois without power - instead of still moving at 1km/h, just have them stop, but as soon as it happens, send out a warning to the player, and after a while, teleport that vehicle to the nearest depot*. Then, consider the potential speed in routing (I'm not sure if that's already done, but if so, it's only done for way speeds, not for vehicle speeds on ways).
This would mean two things: On one hand, the choice between the non-electrified and the electrified track would be smart enough even in less clear situations, such that even if something unintended happens, it's not something completely unexpected. (like trains driving across half the map because there technically is another route completely electrified, or trains going at a fraction of their speed due to using an unelectrified track for being slightly shorter)
On the other hand, you wouldn't have to bother with trains ending up unable to move, since even if it happens, the game handles them. Since speed becomes part of routing, any tile that causes a speed of 0 would be blocked.
As a side effect, the same logic could be used for weight limitations, not only for hard limit, but for soft limits as well - ie. not only can a track be passable or not depending on the weight, but it might limit speed depending on weight, and heavy vehicles can only go at fraction the normal nominal speed of the track. Which I, personally, would think a much more interesting feature than electric units on unelectrified tracks anyway ;)

As you may know by now, this is just me spitting out ideas without worrying whether it can even be reasonably programmed. I guess my points are, mainly, that routing is very important in this matter, and that it might be better to change the foundation, rather than 'hacking' this in.

Also in real world, usually the engine is exchanged unless there are special construction works. Dual traction exist when the electric is just an extra push for a slope (that exist still in very few places, but the electric engine will uncouple after the slope). Because engines are heavy, and usually you do not want to haul them needlessly.
Note that THLeaderHs convoi coupling patch could allow for something similar to that: A convoi consisting of only a diesel locomotive could go between two stations that mark the beginning and end of an unelectrified track, waiting for electric units that need passage, without ever transporting anything itself. There can even be a reason for doing this in real games if you use another players tracks which he refuses to electrify.
Also, the only reason why his patch could not be used to exchange the engine in the first place is that a convoi without engine can't leave the depot. Otherwise, you could have a convoi without engine coupled with a convoi that's only an electric engine, until they disengage and the convoi without engine couples with a convoi consisting of a diesel engine. In the same way. You could have engine-less extra wagons that get detached like 3 stops before a route ends and wait until the engine comes back and they can attach again. Honestly, I think all that's really needed is
A) several convois need to be able to leave the depot pre-coupled (such that those engineless-convois can start somehow)
B) convois without engine, if not waiting for an engine in a station, need to be handled differently (not by going 1 km/h, but by being moved out of the way once it's clear they got stuck)


*the nearest depot, in this case, can be direct line without considering tracks. Maybe the wagons were hauled away by truck ;) It's just so they get out of the way and no longer block everything. Could be an option to activate in other vehicles as well ('if "no route" for too long, teleport to depot'). Clearly, that would not be realistic, but simply a gameplay measure.



It should be noted that what THLeaderH is saying and what others are saying is a completely different case.
What THLeaderH says is that diesel locomotive pulls EMU. Diesel locomotive (and generator vehicle) is added just before entering the non-electrified section to pull EMU. Then EMU can enter the non-electrified section. (Then EMU stops all motors.)
I think other people are talking about dual-mode or bi-mode and Prissi is talking about support locomotives for the slopes.
Yes, the use-cases are different, but the problems of mixed engines are the same.

I think in both cases the problem is in running costs rather than route searching. Because EMU needs a large investment in electrification originally, it should be characterized as a low running cost instead. [...] For dual-mode vehicles, different running costs need to be set in the electrification mode and the non-electrification mode.
You are right that dual-mode vehicles are a different topic and need different running costs depending on mode. However, because the electric mode is much cheaper, I think it should prefer electrified ways in routing still. Furthermore, they probably don't have the exact same power in both modes?
« Last Edit: July 16, 2019, 10:45:33 AM by Leartin »

Offline Václav

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #12 on: July 16, 2019, 10:35:09 AM »
It should be noted that what THLeaderH is saying and what others are saying is a completely different case.
Not at all. In game (and partially also in real world), it does not differ if there is diesel locomotive pulling EMU or if there is unit equipped by both engines (diesel and electric), or if train has both locomotives (diesel and electric). However, units with both engines give a sense (but I have not not seen any yet).

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What THLeaderH says is that diesel locomotive pulls EMU. Diesel locomotive (and generator vehicle) is added just before entering the non-electrified section to pull EMU. Then EMU can enter the non-electrified section. (Then EMU stops all motors.)
I think other people are talking about dual-mode or bi-mode and Prissi is talking about support locomotives for the slopes.
Prissi talked about support locomotives only as example for dual-mode trains, nothing else.

And by the way, EMU (even if pulled by diesel locomotive or DMU) cannot be without electric power - because brakes, air-condition and many other systems still need power. And if that power is not gained from any catenary, it has to be gained from locomotive or DMU.

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In a topic Hybrid trains, James has decided to forgot the bi-mode implementation because it has determined that the effort is not worth it. However, bi-mode vehicles are increasing in recent years and it would be great if implemented. ;)
Dual-mode trains are what we discuss all time. As I wrote above, it does not differ if it is as DL+EMU or DL+cars+EL or EL+DMU.

Offline THLeaderH jp

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #13 on: July 17, 2019, 11:01:41 AM »
I posted this request with a shallow thought and I learned from this discussion that there are many problems for this request, such as routing penalty, running costs, and drawing. Although I think supporting bi-mode train is worth discussing, I would like to withdraw the request to pull EMU by diesel locomotives. Thank you for your opinions.

Offline Leartin at

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #14 on: July 17, 2019, 02:09:49 PM »
I think it's a worthwhile discussion, especially since your coupling patch changes the status quo, so thank you for starting it. It's just not something the coupling patch should depend on.

But since I mentioned it earlier: How do you feel about completely powerless convois that can only be pulled by another convoi, to simulate a switched loco? I'm pretty sure players would try to do that anyways, perhaps with "invisible" vehicles of veeeery low power, just so a convoi counts as powered even though it behaves like an unpowered one.

Offline Ranran jp

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Re: Electric convoys enter non-electrified track with diesel locomotives
« Reply #15 on: July 17, 2019, 02:38:03 PM »
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And by the way, EMU (even if pulled by diesel locomotive or DMU) cannot be without electric power - because brakes, air-condition and many other systems still need power. And if that power is not gained from any catenary, it has to be gained from locomotive or DMU.
Yes, that's right. Japan's EMU, which can enter the non-electrification section, solves braking problems and service power problems in a special way.
In order to secure service power supply, engines for power generation are installed on diesel locomotives, power supply vehicles, or EMU.
It has equipment that works in conjunction with the diesel locomotive's brake instructions. (Air brakes such as freight cars are insufficient for braking power.) All EMUs that can enter the non-electrification section (with in service) are special EMUs.

It is the same as bi-mode in convoy units. Unlike normal bi-mode, the EMU's motor is powered off and requires an additional vehicle.
I think convoy coupling is irrelevant if bi-mode is executable with simutrans. That is, THLeaderH's example can be achieved by considering its EMU as a bi-mode vehicle.