Acceleration/deceleration of trains is unrealistic

[GeneralGeldenhuys]

Please adjust the maximum acceleration/deceleration. It should be lower. It looks like the trains depart like rockets out of the stations and stopping like a race car. Think of the discomfort in the trains!

[gGeorg]

Train advantage over road is for long run trip. But map is scaled down,so the acceleration is scaled up. That is obvious.

[><Ce|\|T><]

Originally posted by GeneralGeldenhuys:

Please adjust the maximum acceleration/deceleration. It should be lower. It looks like the trains depart like rockets out of the stations and stopping like a race car. Think of the discomfort in the trains!

Replace the sound of train braking by the sound of people screaming :D

[GeneralGeldenhuys]

Originally posted by ><Ce|\|T><:

Originally posted by GeneralGeldenhuys:

Please adjust the maximum acceleration/deceleration. It should be lower. It looks like the trains depart like rockets out of the stations and stopping like a race car. Think of the discomfort in the trains!

Replace the sound of train braking by the sound of people screaming :D

Oh no! The horrors when I loaded the game up for the very first time in September!!!

[LennZ]

Actually, rockets would accelerate at an increasing rate as they speed up, as they become lighter by burning fuel. TF trains follow a hyperbolic acceleration curve, which means that it's highest when coming from a stand still. So they accelerate more like a rocket that's burning negative fuel.

What happens is that the tractive effort of a train isn't actually what limits the force, it's effectively circumvented at low speed. This leads to weird behavior like super heavy trains climbing slopes they shouldn't be able to, and lightweigt trains turning the passengers into pulp as they accelerate out of the station.

[GeneralGeldenhuys]

Originally posted by LennZ:

Actually, rockets would accelerate at an increasing rate as they speed up, as they become lighter by burning fuel. TF trains follow a hyperbolic acceleration curve, which means that it's highest when coming from a stand still. So they accelerate more like a rocket that's burning negative fuel.

What happens is that the tractive effort of a train isn't actually what limits the force, it's effectively circumvented at low speed. This leads to weird behavior like super heavy trains climbing slopes they shouldn't be able to, and lightweigt trains turning the passengers into pulp as they accelerate out of the station.

The problem is not the tractive effort, but the maximum a value. They should decrease it to something like 0.6m/s^2 as maximum acceleration/deceleration.

[LennZ]

The tractive effort is basically the maximum acceleration, at least in real life. It just doesn't work that way in TF - intentionally or because of a bug.

[uzurpatorex]

If anything, the acceleration should be sped up. If average distance between cities IRL is 20km, and average in TpF world is approx 500m, then to keep a realistic speed curve over the entire line acceleration in the game should be about 40 times more pronounced then IRL.

Besides - in reality most railroads limit acceleration to about 1.5m/s^2.

[GeneralGeldenhuys]

Originally posted by LennZ:

The tractive effort is basically the maximum acceleration, at least in real life. It just doesn't work that way in TF - intentionally or because of a bug.

Tractive effort does work as intended. You don't understand what it is and how it affects the train. As said before, tractive effort determines the grip a locomotive has and will only play a role on sloped tracks. Tractive effort will determine between pull or wheelslip.

There is already a maximum acceleration value, but it is too high in my opinion. It should be at least 0,6-0,8m/s^2. What determines a train speed on a slope is power (horsepower/kilowatt). The higher the power, the faster a train can run up against a hill.

[gGeorg]

Originally posted by GeneralGeldenhuys:

, tractive effort determines the grip a locomotive has and will only play a role on sloped tracks.

No

[Robbedem]

Originally posted by GeneralGeldenhuys:

...
There is already a maximum acceleration value, but it is too high in my opinion. It should be at least 0,6-0,8m/s^2. What determines a train speed on a slope is power (horsepower/kilowatt). The higher the power, the faster a train can run up against a hill.

Actually, German passenger trains are designed to accelerate and decelerate at 1,1m/s²
So 0,6 and even 0,8 would be low for passenger trains, but it's about right for freight trains though.

However, I think the current deceleration (and I assume acceleration too), is set to 2m/s²
I think this is to allow smoother operations for trains. F.e. a train that has to stop for a red light will use much less time and therefore disrupt the lines spacing and frequency much less with higher ac-/deceleration

EDIT: the higher ac-/deceleration is probably also used to improve the usability of high-speed trains. Especially the TFV needs a lot of track to brake if you have only a deceleration of 1m/s², doubling the braking force, also halves the track needed for a train to come to a full stop.

[Tuna]

Given how fast time flows in the game, the trains are way too slow!

[GeneralGeldenhuys]

Originally posted by gGeorg:

Originally posted by GeneralGeldenhuys:

, tractive effort determines the grip a locomotive has and will only play a role on sloped tracks.

No

Care to elaborate? Otherwise I just assume you being stupid.

[uzurpatorex]

Originally posted by GeneralGeldenhuys:

Originally posted by gGeorg:

No

Care to elaborate? Otherwise I just assume you being stupid.

F = ma
F = min( P / V, TE )

ma = min( P / V, TE )

a = min( P / V, TE ) / m

Therfore - acceleration is dependant on tractive effort when P / V ( power to speed ) is higher then maximum TE. THis happens for lower speeds. Therfore TE is important for all cases of acccelerating from 0 to a certain threshold. If your train is beloc the threshold then no matter how much power it can produce, it will actually produce:

P = TE * V

So if your train is going at 5km/h and has 200 kN TE rating, then it is producing 1MW regardless of power rating of the locomotive.

[GeneralGeldenhuys]

Originally posted by uzurpatorex:

Originally posted by GeneralGeldenhuys:

Care to elaborate? Otherwise I just assume you being stupid.

F = ma
F = min( P / V, TE )

ma = min( P / V, TE )

a = min( P / V, TE ) / m

Therfore - acceleration is dependant on tractive effort when P / V ( power to speed ) is higher then maximum TE. THis happens for lower speeds. Therfore TE is important for all cases of acccelerating from 0 to a certain threshold. If your train is beloc the threshold then no matter how much power it can produce, it will actually produce:

P = TE * V

So if your train is going at 5km/h and has 200 kN TE rating, then it is producing 1MW regardless of power rating of the locomotive.

I know that, but maximum acceleration will limit the tractive effort being used. If we limit max acceleration to 0,8m/s^2 and it is a 800t train, then we need 640kN. If the train can develop 900kN, only 640kN will be used.

To throw the case of a train has 900kN, then all of it must be used, will cause the train to accelerate over 1,125m/s^2 and it will cause discomfort and it looks unrealistic!