Train acceleration calculator

[Orthas]

Hi, I made a little spreadsheet to help choose the right locomotive and the amount of carriages in a train. You can calculate acceleration, and also get some feedback on tractive effort and hill-climbing ability. It can be found here: https://docs.google.com/spreadsheets/d/1FW5R8aq3E88py-sTObi5s-w8U1z_li8Q9Mzp1ZQ9iPU/edit#gid=0.

[Saint Landwalker]

Interesting! I was literally working on my own version of this when I saw this post. Unfortunately, mine version is the "made by a non-engineer" version, so it's probably horribly wrong.

I input the numbers for a Prussian G3 hauling ten Bavarian carriages—108 t, 160 KW, 60 KN. On your spreadsheet, it would take 65.1 seconds to reach max speed (50 km/h). According to the formulas I was using, I had it reaching max speed (over flat ground) in about 27 seconds.

Would you mind walking us non-engineers through your formulae, particularly the terminal velocity on incline, traction threshold, and time-to-reach-speed?

[><Ce|\|T><]

Did you know that it's possible to do a combobox to select the train data directly ?

Formula terminal v on steep incline... 14 * power / mass ??? where did you get this kind of formula ?

Formula for time to reach speed seems incorrect to me.

[Orthas]

Formulas are based on empirical testing within game. Many things are still missing, like how trains function when under the traction threshold. All formulas and testing are explained in detail in these two posts: https://www.reddit.com/r/TransportFever/comments/5e3jme/the_impact_of_of_tractive_effort_on_slopes/ https://www.reddit.com/r/TransportFever/comments/5dm6ej/short_analysis_of_train_physics/
If you have better tested estimates, I'd be happy to make the model better.

I will do a dropdown to select locomotive data hopefully tomorrow when I have time.

[Orthas]

There is now a comparison tool with dropdown menu to choose locomotive data.

[gGeorg]

Originally posted by Orthas:

There is now a comparison tool with dropdown menu to choose locomotive data.

Comparation is greate.
Would you add compare for a line time travel?
One field with a lenght of route. Asume even route, no slope.
Result would be total time for speed up, go at his own max speed then slow down. Some trains like TGV will not reach even max speed...

[Orthas]

I'll have a look later tonight/tomorrow morning about that.

[Saint Landwalker]

Orthas, a couple more questions about the latest version of the spreadsheet:

1) According to the formulas, it doesn't look like a locomotive's tractive effort matters in its acceleration calculation. A locomotive with 0 KN of tractive effort and one with 50,000 KN of tractive effort have the same acceleration curve. Is that actually game-accurate? (Obviously the game itself isn't accurate, if that's true, but game-accuracy is the one we're concerned with here.)

2) Similarly, does traction threshold play any role, game-wise, in a locomotive's performance, or is it just there for "technically this is how things should be" purposes?

[philmo]

Really good thread - is this the most recent post on this subject as I have been looking for a tool to help decide on the best engine and coach mix. For this spreadsheet I presume I have to enter enter : Power (kW), Tractive effort (kN), Mass of loco (ton) for each engine ? or is this a look-up to locomotive data (for me they are fixed cells not calcs). And do I have to manually enter the coach weights also below to get to my answer ?

Thanks

[Stormmaster]

So far I have been using an older version of this spreadsheet (I downloaded it long ago) and came here looking for a newer version. This has some improvements over the old one. Great, thank you.

Also, when entering the mass of wagons don't forget the mass of cargo or passengers. The game doesn't mention it, but it was introduced in one of the updates quite a while ago (and is noticable in details tab when a train is loading or unloading). I read somewhere in discussions that 1 unit of cargo weighs 1.2 tons and 1 unit of passengers weighs 0.2 tons.

Originally posted by Landwalker:

Orthas, a couple more questions about the latest version of the spreadsheet:

1) According to the formulas, it doesn't look like a locomotive's tractive effort matters in its acceleration calculation. A locomotive with 0 KN of tractive effort and one with 50,000 KN of tractive effort have the same acceleration curve. Is that actually game-accurate? (Obviously the game itself isn't accurate, if that's true, but game-accuracy is the one we're concerned with here.)

2) Similarly, does traction threshold play any role, game-wise, in a locomotive's performance, or is it just there for "technically this is how things should be" purposes?

In another thread I found these explanations of Tractive Effort.

Originally posted by Robbedem:

The game (Train Fever, I suspect it's stil lthe same in Transport Fever*) uses a simplified acceleration curve for all trains.
First a train will accelerate at it's maximum acceleration, determined by the traction/mass.
acceleration = traction / mass
(there might be a maximum acceleration too, independant of any other properties, but I haven't seen this)

Very soon however, the acceleration will diminish because of limited power.
The acceleration will be dependend on the power/mass and the speed of the train.
For a flat track:
acceleration = power / ( mass . speed)

So in practice (on a flat track), the acceleration will be the minimum of (traction or power/speed) divided by the mass of the train.
Keep in mind that the speed is in m/s (SI units)

f.e. a train with these properties: 1000kW, 100kN, 200 tonnes
will have it's acceleration decline from 10m/s (=36 km/h)

At that speed, the acceleration is still the maximum : 0,5m/s²
At a speed of 40km/h, that acceleration has dropped to 0,45m/s²
At 80km/h, the train will accelerate at only 0,225m/s²



*Train fever had a braking of 1m/s², while Transport Fever has a braking of 2m/s².
I would have to check to see if the acceleration values are doubled too. (no time today sadly)

[Stormmaster]

Orthas, I've just noticed that the spreadsheet isn't working properly. "Compare" tab doesn't allow to choose locomotives, and "Copy of Compare" shows top speed of Locomotive B for both locomotives.