Difference between revisions of "Max Curve Speed"

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(extended. Source: http://hg.openttd.org/openttd/trunk.hg/file/915aed927f42/src/train_cmd.cpp#l298)
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The speed a normal rail curve allows can be calculated using the following formula:
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Making trains keep their speed at maximum is key for keeping traffic fluent.
  
Maximum speed in km/h = 231 - (13-CL)^2<br>
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==Numbering Convention==
CL in the formula is limited to a maximum of 13.
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For two curves in the same direction, CL is the number of half-tiles between the 45°-turns. If three or more curves are within the length of a train, the game calculates an average curve length based on the part of the train which is between those curves and the total number of total curves - 1.
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First of all it is necessary to realize how do we name curves by numbers.
This can lead to strange effects: A third bend can increase the average curve length and allow a higher speed of the train.
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This is fairly simple - if you turn on the counting in game interface
  
Two 45°-turns with a single diagonal half-tile in between will always limit the speed to 88km/h, independent of other curves.
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Advanced settings -> Interface -> Display Options -> Display measurement tooltip...
  
[[Image:slow_corners.png|frame|none|An example showing which corners are affected]]
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Then we just use those values the game says. An exception however comes when the used curves are in between - one from each. In that case when for example between 1 and 2, we call it CL1.5 as the picture below demonstrates.
  
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[[Image:Curve_convention.png|600px]]
  
Monorail and maglev use the same formula but get a 50% and 100% speed bonus respectively, resulting curve speeds are shown in the graph below. Tilt increases the maximal speed by 20%.
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==Travel speed mechanism==
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Here is how it is declared whether a train will slow down on a curve and eventually how:
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[[Image:Curve_mechanism.png|600px]]
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==Curve Speed==
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Easiest way to test how fast a train can go through a curve is to simply test it, but it can also be counted by taking:
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the base curve speed table, and multiplying it by monorail or maglev bonus (50 or 100%)  and/or tilt bonus (20%), and eventually also short wagons need to be considered as they can travel through curves faster. The short wagon bonus is about the same as tilt for NUTS short wagons (half the length of full length wagon)
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The base curve speed can be found on the openttd wiki, but this graph demonstrates it too (plus monorail and maglev as well)
  
 
[[Image:curve_speeds1.png]]
 
[[Image:curve_speeds1.png]]
  
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==Special Curves==
  
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There are not always just full curves, but also Sbends and such.
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Counting their maximum speed is quite complicated so it is easier to just try it in game if the train slows down in the specific curve or not.
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[[Image:slow_corners.png|frame|none|An example showing which corners are affected]]
  
 
== See Also ==
 
== See Also ==
 
* For some more detailed information see {{User|Mark}}'s blog post: http://www.openttdcoop.org/blog/2009/05/13/about-curve-lengths/
 
* For some more detailed information see {{User|Mark}}'s blog post: http://www.openttdcoop.org/blog/2009/05/13/about-curve-lengths/
 
* [[User:KenjiE20/Webster#Curve Length Calculator|Webster's helper function]]
 
* [[User:KenjiE20/Webster#Curve Length Calculator|Webster's helper function]]

Revision as of 20:37, 24 May 2013

Making trains keep their speed at maximum is key for keeping traffic fluent.

Numbering Convention

First of all it is necessary to realize how do we name curves by numbers. This is fairly simple - if you turn on the counting in game interface

Advanced settings -> Interface -> Display Options -> Display measurement tooltip...

Then we just use those values the game says. An exception however comes when the used curves are in between - one from each. In that case when for example between 1 and 2, we call it CL1.5 as the picture below demonstrates.

Curve convention.png

Travel speed mechanism

Here is how it is declared whether a train will slow down on a curve and eventually how:

Curve mechanism.png


Curve Speed

Easiest way to test how fast a train can go through a curve is to simply test it, but it can also be counted by taking:

the base curve speed table, and multiplying it by monorail or maglev bonus (50 or 100%) and/or tilt bonus (20%), and eventually also short wagons need to be considered as they can travel through curves faster. The short wagon bonus is about the same as tilt for NUTS short wagons (half the length of full length wagon)

The base curve speed can be found on the openttd wiki, but this graph demonstrates it too (plus monorail and maglev as well)

Curve speeds1.png

Special Curves

There are not always just full curves, but also Sbends and such. Counting their maximum speed is quite complicated so it is easier to just try it in game if the train slows down in the specific curve or not.

An example showing which corners are affected

See Also

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