[sumo-user] SUMO yellow side marker lights - What is the controlling mec

[Ben Duprey <blduprey@xxxxxxxxx>]

Hello,

I am a new user of SUMO and wanted to better understand the nature of the yellow side-lights on vehicles. 

Summary

• When SUMO detects that the planned route of the vehicle requires it to change a lane or turn at a junction, the yellow side marker lights will be triggered. This suggests that these represent directional lights. 
• I believe this logic is internal to SUMO. 
• However, I have some simulations with an ego and a single traffic vehicle / NPC in which the ego does not change lanes and does not turn at an intersection, and still the yellow side lights are shown. 
• I have searched some SUMO documentation but haven't found information regarding these yellow side lights.

Any information as to their operation would be appreciated. 

Thanks

-Ben