Train Weight Crazy Confusing

[dannyman]

Latest preview build and Britain-Exp 0.8.3
1916
Rail, electric depot, LSWR Suburban EMU


Individual units weight 25-30t.  Okay, no problem, should run fine on Wooden Sleeper Steel Rail (69t)
Assemble three cars ...
Weight: 85.0t, 103.5t


Can I assume that station length 2 -> max 52t for purposes of track limits?


UI (depot screen) could make things clearer ...


-d

[jamespetts]

The weights have been rationalised in the latest release (0.9.0).

[greenling]

Hello Jamespetts
I have to the new train weight calculating some news technicals questions.
can you there help?

[jamespetts]

I can certainly try, Greenling. What are your questions?

[dannyman]

So, another example with Britain 0.9.0 ..

Year: 1813
Roads have weight limit of 0t, 1t, or 3t

Buy a pair of horses (Weight: 1t, Axle load: 0t) and Stage Wagon (piece goods) (Weight: 1t, Axle load: 1t)

Okay, so, what is the axle load of the convoy?  If you assemble the convoy, it says:

Weight: 2.0t, 7.0t (The help text could explain, I assume empty / max?)

Okay, so ... two axles, right?  Is that actually 1t / 3.5t?  The "axle load" figure, as far as I can tell, is just confusion.

Anyway, there is some trouble with the latest Britain-Exp because the convoy comes out to 6.38 t when fully loaded, and the most expensive road I can build is 3t ...
Yup, upgrading to gravel road ... convoy still stuck.

Anyway:
1) It would be nice if the weights shown in the vehicle components could be obvious to the player in terms of road capacity:
1.a) Weight?  Axle Load?  Huh?  No, player needs:
1.b) Weight empty, weight at max load.  (In terms of way max weight.)
2) Maybe hard to code, but calculate the maximum weight that could be hauled to its destination, and only load cargo to that limit.  At least then your expensive new service keeps moving, even if on the empty side.
3) Or, maybe some kind of warning at the depot before the convoy comes out when max load exceeds potential paths to complete route.

And yet, my 2.19t livestock drover goes fine on a bridle path with 0t load limit .. because they have no axles?


Ahhh ... if I run a single pair of Pack horses (piece goods) they run fine on a bridle path.  But if I create a 5-pair convoy then they exceed the weight limit.   

Cheers,
-danny

[jamespetts]

The new weight limit system is based on axle loads for all ways except bridges, and total convoy weights for bridges. Things that are not wheeled vehicles at all (pack horse trains, livestock and drovers, post boys) have no axle load, and can therefore travel on ways with a 0t maximum axle load. The axle load is not necessarily dependant on a vehicle's weight and does not vary with a vehicle's load, nor with the number of vehicles in a convoy.

For bridges, the position is different. Here, the total loaded convoy weight is used, divided by that proportion of the convoy that can be on the bridge at any one time. I presume that that is what is happening with your five pair set of pack-horses: they are, I presume, needing to cross a bridge for which all five of them are over-weight.

[dannyman]

The new weight limit system is based on axle loads for all ways except bridges, and total convoy weights for bridges. Things that are not wheeled vehicles at all (pack horse trains, livestock and drovers, post boys) have no axle load, and can therefore travel on ways with a 0t maximum axle load. The axle load is not necessarily dependant on a vehicle's weight and does not vary with a vehicle's load, nor with the number of vehicles in a convoy.

For bridges, the position is different. Here, the total loaded convoy weight is used, divided by that proportion of the convoy that can be on the bridge at any one time. I presume that that is what is happening with your five pair set of pack-horses: they are, I presume, needing to cross a bridge for which all five of them are over-weight.

There is a 5t bridge on the route, yes.  Thank you for explaining.

I guess what would be really handy then, are figures in the convoy purchase and info dialogs that clearly spell out the max road weight and max bridge weight.  Something like:

Max axle load: %d (road limit)
Max weight: %d (bridge limit)

Does it get more complicated still?  Like bridge weight would be bridge weight per tile .. you have to figure the heaviest vehicles in the convoy per tile space?  If that's the deal, having the program figure out the bridge limit weight would be critical.

I'll try playing with this understanding in mind and see if the game is more enjoyable.  Thanks!

[jamespetts]

Bridge weights do depend on the maximum proportion of the convoy that can be on the bridge at any one time. However, working out the maximum weight of any given schedule is actually much, much more complicated than it first appears: what is the maximum weight of a schedule where there are between one and ten different ways of getting between each pair of points in the schedule, each of which point to point routes have different weight convoy and axle load limits, and where there is anything between no difference in the journey length and a difference in journey length of tens of orders of magnitude between the lowest and highest weight routes?

[dannyman]

Thanks, Jamespetts!

So, as I get it, there are two weights the player needs to worry about:
1) axle load -> the maximum for a way
2) total weight -> the maximum for a bridge

I've taken a stab at "mocking up" what I might hope to say in the depot and convoy dialogs to make this clearer:

Current: https://www.dropbox.com/s/u6oi69667pst8mn/simutrans-exp-before.png
Mockup: https://www.dropbox.com/s/vd5n3mz9i4j2itm/simutrans-exp-mockup.png

Total weight is somewhat easy to understand, but the player doesn't know the weight of a crate or a person or a bundle of mail, but the game ought to be able to quickly do the math.

Axle weight I'm pretty unclear of: is it multiplied by axles or what?

Anyway, based on the screenshot here, my understanding is now that a 2x pair packhorses have:
0t axle limit
4.7t max weight

Therefor they can run over a 0t bridle trail and cross a 5t bridge.

As for calculating the ways and warning players, while it would be very nice, it is very tricky to build.  I think if you give good information in other parts of the UI, then the player can handle figuring out for themselves.

Cheers,
-danny

[jamespetts]

Yes, that is correct: those are the two weights that are relevant. Thank you for suggesting an alternative layout for the depot/convoy windows. This is not as straightforward as might first appear, however: the suggested changes seem to have obliterated the braking distance and rolling resistance data, which are important. Also, the suggested display for the full weight in the lower part of the convoy window would give the false impression that it is the vehicle's loaded weight, rather than the convoy's, that would count for a bridge, which would be confusing to players. There also seems to be a removal of a convoy's empty weight, which is useful for the player to know to understand its acceleration and braking characteristics.

As to axle loads, these can be, but are not necessarily, the total loaded weight of a vehicle divided by a number of axles specified in the .dat file. The reason that these are not necessarily the weights used is that some vehicles have uneven weights on different axles: steam locomotives, for example, have more weight on the driving axles than on other axles. In these cases, the axle loads are specified directly in the .dat files.

[greenling]

Hello Jamespetts
Sorry for my delayed posting.
What make Simutrans exp then i take a addon in the pak128britain exp pakset that the entry axles=4 not have?

[jamespetts]

Do you mean what is the axle load if nothing is specified in the .dat files specifying the number of axles or the axle weights? In that case, the number of axles is presumed to be 2.

[dannyman]

Yes, that is correct: those are the two weights that are relevant. Thank you for suggesting an alternative layout for the depot/convoy windows. This is not as straightforward as might first appear, however: the suggested changes seem to have obliterated the braking distance and rolling resistance data, which are important. Also, the suggested display for the full weight in the lower part of the convoy window would give the false impression that it is the vehicle's loaded weight, rather than the convoy's, that would count for a bridge, which would be confusing to players. There also seems to be a removal of a convoy's empty weight, which is useful for the player to know to understand its acceleration and braking characteristics.

So ... it is a suggestion.  We probably would want Max speed to fit in the left column anyway, so you could change "brakes from max speed in 0 - 1m" to "brakes from max in 0 - 1m" or even just really, tell me the braking distance:

Max Speed: 7km/h @ 4.68t; 1m to brake
Max Speed: 7km/h @ 4.68t; 0-1m to brake

As for removing the empty weight, I would be interested how many players want to know this.  I myself have never sat there thinking "well, if the vehicle weighs this much and the braking force is this many kilonewtons then ... ?"  But I understand there are different kinds of players.

That opens up the consideration as to what you put on the convoy dialog vs the Details screen.  I just discovered the totally awesome metric as to how much money the convoy would make per km ... that would be cool to have in the Revenue line, imho.  Operating cost and what I might expect to see in revenue, then I can gauge how successful my line is!  Conversely, the empty weight, if it is not something that players particularly feel the need to see up top, is probably already in the details screen.