Situations

Situations are used to group a train with operating and environmental conditions.

Overview

Each situation contains one train object, one track object, one environment object, and one group of receivers . There are only a few limited parameters that are unique to a situation.

It may be that there is a certain change to the track that is being investigated. In this case, a user might specify two situations with identical library objects for the train, environment and receiver groups, but with different library items assigned to the tracks. The user will then be confident that the only differences between the two calculations are due to differences in the track.

Input Parameters

Name	Data type	Unit	Comment
Label	Text	-	A short name for this situation.
Enabled	Checkbox	-	Select whether this situation will be enabled in the calculations.
Description	Text	-	A paragraph to describe what this situation represents etc.
Train speed definition	Choice	-	Select whether the calculations are to be performed for a train running at a single speed, or for a range of defined speeds.
Speed range	-	-	Click the button to the right to open a dialog to define the train speeds to be used in the calculations (if Train speed definition is set to “Speed range”). In the dialog, speeds are added as positive comma-separated values, which are in km/h, in ascending order. To include calculations at standstill, set the first value to 0.0 km/h. N.B. when using a range of speeds, “Auto pass-by mode” is used (see below).
Train speed	Number	km/h	The speed of the train (to the left with respect to the graphics view). Negative values are not allowed. To calculate external noise levels at standstill, set this to 0.0 km/h.
Auto pass-by mode	Checkbox	-	Select this to automatically calculate some appropriate time window parameters. Note that the resulting ‘Pass-by duration’ and ‘Time increment’ settings will depend on your project settings.
Pass-by duration	Number	s	Used for the calculation time window. Please ensure this is long enough (consider the train length and speed).
Time increment	Number	s	This affects the time resolution of the pass-by calculations. For very high speeds with highly directional sources, this should be set to a low value.
Include doppler effect	Checkbox	-	Specifies whether the doppler effect is included in the external noise calculations (and auralisation output).
Roughness input	Choice	-	For rolling noise calculations, the roughness can be specified as a combined wheel and rail value, or separately for the wheel and rail, with or without a contact filter applied. Alternatively, the TSI roughness spectrum can be selected.
Contact filter model	Choice	-	Allows the contact filter to be specified as DPRS or Remington.
Track support model	Choice	-	Specify the model used for the track: continuously supported (the traditional assumption) or discretely supported (a recent formulation).
Wheel lateral offset	Number	mm	The lateral offset of the contact point on the wheel (+/- 40mm allowed).
Combined roughness file	File	-	If the roughness input has been selected to be a ‘combined roughness’, the roughness input file location is specified here (with ’.to’ file extension ).
Rolling noise sides	Choice	-	The sides to use when calculating rolling noise: both wheel/rail sides, or just the left side.
Train	Lib. item	-	The library item for the train object.
Track	Lib. item	-	The library item for the track components.
Environment	Lib. item	-	The library item for the environment conditions.
Receivers group	Lib. item	-	The library item for the collection of receivers.