[FRDF] How to decide how many wagons you can have in a train

Post by **uzurpator** » 27 Jan 2005 17:52

zuu - yes Tractive Effort is the force the loco can exhert on the track.

Hyronymus - your formula is bull.

450 kN, 80 tons per car (full) gives us amazing 0,56 wagons. And still you are playing the game for the player. Just let ppl to decide what they want to play.

Also TE is limited by locomotive weight at low speeds (below 15 km/h) weight is all that matters.

Steve · Post by **Steve** » 27 Jan 2005 18:00

You can play with all the little stats as much as you want. The thing is, people just want to play the game. Agreed, some might want to know a little more, but you can always add a little history section for each train for reference.
I recommend just displaying Speed and Power no matter what formulas you use underneath. And let the player use as many wagons as he likes.

It generally goes against what i consider good game design, but you could always make more realistic systems, with more limits and considerations, an option (defaultly on for hard settings).

I guess it'll actually make the game more interesting with some things like this. Take common road design in the italian mountains for instance, they need to weave up the mountain. Having to do this to get a nice goods train from A to B would be great. (With a tunnel being far too expensive of course).
But i don't see Average Joe caring enough to do the same though. They'll just go over and let the train suffer a *slight* drop in speed.

Post by **uzurpator** » 27 Jan 2005 18:05

Steve - my point exactly.

The three "real" stats for any wheeled vehicle are Tractive Effort, Power and Max Speed. Just use the well known TTDPatch formula for this and all is set.

TE - sets how much a vehicle can pull
Power - sets rate of acceleration
max speed - sets max speed

Zuu · Post by **Zuu** » 27 Jan 2005 18:18

I have to agree with Steve, that it's important that we can tell the user that this setup will work ond this don't. I think it would be good if loco had a label that says how many tons it can pull. Then the user can (if he is not to lazy) calclate how many wood wagons he can have given that he knows how heavy they are.

But how the amount of tons a loco can pull is calculated is not important for the user.

Then, I havn't taken hills into acount. Perhaps we have to make it like this: If a loco can pull X tons on flat, it can do it up-hill too, but it will pull slower. The steeper hill, the slower it will go. I gues this is aginst the physics, but we cant have to comlicated rules, as the players are just players, and not engineers.

Hyronymus · Post by **Hyronymus** » 27 Jan 2005 18:33

uzurpator wrote:Hyronymus - your formula is bull.

450 kN, 80 tons per car (full) gives us amazing 0,56 wagons. And still you are playing the game for the player. Just let ppl to decide what they want to play.

Also TE is limited by locomotive weight at low speeds (below 15 km/h) weight is all that matters.

It was just an attempt to make it measurable, sorry if that disturb you so much. Anyhow, with the suggestion you made to let TE only influence how much it can pull you don't disagree with me. All that I did was *trying* to add a way to immediatly translate that in the # of wagons it can pull (all this in the light to prevent players from creating too long trains that in the end don't get moving at all). To me asking how much they can haul is asking how many wagons they can haul. If you quantify the amount of weight a 450 kN engine can pull (maybe someone can find a better formula?), what does it matter to do the maths for the player?

jfs · Post by **jfs** » 27 Jan 2005 18:45

I'm pretty sure the Railroad Tycoon series (at least RRT1 and RRT2) take TE into account, but they never display it directly. Instead they have a chart for each locomotive, displaying its top speed when pulling X carriages at grade Y.
Perhaps something similar could be implemented?
1. Let the user build the train consist, without locomotives.
2. Give the user a list of locomotives suited for pulling this consist.
3. Let the user decide on which locomotive(s) to use based on calculation about top speed at various inclines, when pulling an X percent loaded train.

I know this is a bit reversed compared to the way one usually builds trains in TT/RRT (first locomotive and then carriages), but it might work well.

Post by **uzurpator** » 27 Jan 2005 18:47

Maybe we could use something in a kin of RT3 - a table that shows the data for speed with a train of a certain weight on a certain grade.

We'd use the proper model on the inside and give the player a convinient front-end at the same time.

Post by **uzurpator** » 27 Jan 2005 18:51

Hyronymous - on a level track a locomotive with 450 kN of tractive effort can pull about 12000 tons worth of train. Probably more if it is an aerodynamic train. On a 6% grade this weight would be down to circa 500-800 tons.

There is no formula to calculate if a loco is viable for a service - it is done with trail and error in reality - and so it should be done in the game.

Zuu · Post by **Zuu** » 27 Jan 2005 19:03

Well, if we go for the TE idea where you cant tell how many vehiles a loco can pull, I think we shall display maximum seepnes that the train can pull up-hill. Togeather with a tool that can tell how steep a slope is, the player can have at least a good guess if his train is vaild.

If we allow players to run trains that wont be able to go up-hill at some places, either the pathfinder must be able to sort that out (preferable) or there must be a big red button to press when youre train is stuck and cant get anywhere.

Steve · Post by **Steve** » 27 Jan 2005 19:27

I like what jfs suggested. If you add labels to the engine list such as Cargo, High speed Passenger, it'll help users see what's what without examining all the stats.

Oh, we could even add a novelty character that'll point out good buys! Paperclips are taken, perhaps a talking Mushroom?

Hyronymus · Post by **Hyronymus** » 27 Jan 2005 19:53

The RTT approach is certainly user-friendly but only because it allows up to 6(8) wagons. I thought we wanted something more? What kind of a table does that yield? But whatever we decide, the problem still lies there (and zuu pointed to it): what will we do when the player buys a too heavy train nevertheless?

PJayTycy · Post by **PJayTycy** » 27 Jan 2005 20:48

In Railroad Tycoon (2 and 3), a train always moves. If he would normally not be able to go uphill, the speed drops to 1 mph, but it still moves.
While I'm not really happy with that idea, it does eliminate a lot of difficulties.

I agree with uzurpator that it should be possible to haul 60 empty cars uphill, and run the same 60 cars fully loaded downhill.

hmm, so basicly this discussion has turned into a user-interface discussion.

We have 2 places where this issue comes into play :

When buying a new loco
When creating a schedule

(And we didn't even consider trains with more than 1 loco yet, or attaching/detaching loco's...)

There are just too many "what if's" to this problem (ie: grade uphill, downhill, empty wagons, more loco's, ...). When a player buys a train, these are all unknown untill the schedule is made. Once we have the schedule, we can say for each trip between stations if it's gonna be possible or not (we know the wagons, locomotives, and can check the maximum grade on the route). So, maybe we should let the players create a schedule first, and only "buy" the locomotives and wagons when it's complete.

Zuu · Post by **Zuu** » 27 Jan 2005 20:57

But still, what if the player changes the track, or the route. Well the rute chang could be checked. But loop throught all trains when changing a slope would take some time. Or maybe not, if you know what have been changed. But there will be situations where the player changes the track and/or layout and the computer will miss that, untill a train is catched in the trap.

One thing you can do is if the train contain cargo, you can trow away the crago, so the train becomes lighter and hoptfully make the hill. But this cant help all. So shall we than start to destroy the wagons if that is not enoght?

Am I to destructive?

Hyronymus · Post by **Hyronymus** » 27 Jan 2005 23:50

You're a bit destructive, but that's OK (for now). I rather not start it all over again because I hate to be depicted as annoying but... Let's see what premisses we got sofar:

a too heavy train getting stuck on track seems unfavourable to the majority
preventing this from happening altogether sounds as the best solution
a train should be capable to pull as much as it's TE allows

If I'm forgetting a hallmark of the previous discussion please edit the list in your reply (and try to dream of a solution). Good night

!

Post by **uzurpator** » 28 Jan 2005 04:08

I think the RRT approach is the best - if the train is about to stall (because the locos cannot pull the train uphill) then we should allow it to run at 1 mph (as it solves tons of problems) and penalize the train with increased wear.

Steve · Post by **Steve** » 28 Jan 2005 10:05

The 1mph idea is good. I also suggest making some sort options on the train list, so it shows any trains that are having efficiency problems. Then the trains have time to take their routes to encounter these problems, rather than us have to check for them straight away. It would have to give a description of the problem and zoom to the spot where it occurs. Perhaps even give a solution for the user.

jfs · Post by **jfs** » 29 Jan 2005 16:35

To continue it as a user interface discussion: A golden rule in HCI is "always let the user do anything". Just because something doesn't really make sense it doesn't mean the user shouldn't be allowed to try it. Maybe put a (not too intrusive) warning up, but still allow it.
So if the user builds a train that'll not always be able to run properly (eg. it can run fine when unloaded, but is far too heavt loaded), give a warning but still allow the user to do it. On the other hand, if the user builds a train that'll always be able to run on flat land, but might not be able to climb a 6% grade, don't put any warning. Maybe store some precalculated information about it and put a warning if a route that might cross such a grade is made, but still allow the train to run.

I like the 1 mph idea as well.

Zuu · Post by **Zuu** » 29 Jan 2005 16:50

I agree on the 1mph thing, althorght I think it should be 1kph. Becuse we will use the SI-units, should'nt we?

And with the 1 kph rule, it is quite safe to allow the player to build to heavy trains. But still we have to inform the user if he builds a to heavy train, but allow him to do so, as jfs wrote.

Steve · Post by **Steve** » 29 Jan 2005 17:16

If the gradient is too high, you shouldn't be able to build the track anyway. So i don't think it's unreasonable to just let all trains run rather than be clogged up.

Oh mph is clearly better than kph.

Hyronymus · Post by **Hyronymus** » 29 Jan 2005 19:22

In the FRD there are values for the maximum gradients TE would have, I don't know if anyone can live with them:

RV's: 30%
Trains: 6% (with cogwheel 12%)

Michael Blunk gave me a formula to determine maximum load an engine can pull :

Code: Select all

Fmax = M(adhesive) * µ * g   [F in kN; M(adhesive) in tons, µ = 0,3 ^ g = 9,81 m/s^2

M(adhesive) is based on the weight added to the engine by only the driving wheels.

So with this formula, which Michael uses for the DBset, you can effectively calculate the maximum load, even for different cargo wagons. Is it really hard to create a system that warns when too many wagons are added, based on this formula? If you go with the HCI rule you can always show a warning and let the player decide what to do with it.

EDIT: I think we should SI units as standard, that means checking the FRD for 'typo's' too.

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[FRDF] How to decide how many wagons you can have in a train

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