Re: [sumo-user] Question about lane change reason "urgent" and "speedGai

[Jakob Erdmann <namdre.sumo@xxxxxxxxx>]

Urgent lane changing is a recent and still experimental addition to the default laneChangeModel LC2013.

It can be configured with vType attribute lcSpeedGainUrgency and should almost never occur under the default settings.

You can read about it at https://github.com/eclipse-sumo/sumo/issues/1145

especially the linked commits:

https://github.com/eclipse-sumo/sumo/commit/87bab0453294631cf8323d3546560ac25f2354f9#diff-54ad271cc88e1271ffa69d2f40fd92270af4f5da635de0a12d5ca419c1075915 and

https://github.com/eclipse-sumo/sumo/commit/3265c31fed3434d89712a960069254d9ecf8d987

The behavior of the new attribute is still impacted by

https://github.com/eclipse-sumo/sumo/issues/16302 and

https://github.com/eclipse-sumo/sumo/issues/16303

which limits it's usefulness in the situation where it's most needed: leveling high speed differences between lanes, especially at on-ramps.

regards,

Jakob

Am Di., 17. Juni 2025 um 17:55 Uhr schrieb 노치우 via sumo-user <sumo-user@xxxxxxxxxxx>:

Dear SUMO developers and community,

I am currently researching vehicle lane-changing behavior in SUMO. I would like to understand how the "urgent" lane change reason is computed internally. Specifically, what parameters and equations are involved in this decision process?

Additionally, could you please explain the internal logic or formula used to calculate the "speedGain" reason?

I am using SUMO version 1.23.1, and I have reviewed the documentation(Attachments), but further clarification would be very helpful.

Thank you very much for your support.

Best regards,
Chiwoo Roh

--

Chiwoo Roh                                            

M.S. Student in Transportation Research Institute, Ajou University    

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