Re: [sumo-user] Multi-lane homogeneous congestion

[Jakob Erdmann <namdre.sumo@xxxxxxxxx>]

Hello,

this is as known issue and the current approach for solving it, is via https://github.com/eclipse-sumo/sumo/issues/1145

You'll get a somewhat more even distribution of speeds by setting lcSpeedGainUrgency="3"

It also helps to remove actionStepLength="1.0". By getting more lane-changing attempts you see more cars moving from the middle to the left lane.

Finally, your hard-coded acceleration lane length of 100m is too short. Typical lengths on German and Swiss motorways is 250m. Using all of these

the original speed distribution:

        <edge id="E6">
            <lane id="E6_0" speedRelative="0.20"/>
            <lane id="E6_1" speedRelative="0.48"/>
        </edge>
        <edge id="E7">
            <lane id="E7_0" speedRelative="0.11"/>
            <lane id="E7_1" speedRelative="0.16"/>
            <lane id="E7_2" speedRelative="0.58"/>
        </edge>

changes to

        <edge id="E6">
            <lane id="E6_0" speedRelative="0.30"/>
            <lane id="E6_1" speedRelative="0.48"/>
        </edge>
        <edge id="E7">
            <lane id="E7_0" speedRelative="0.23"/>
            <lane id="E7_1" speedRelative="0.35"/>
            <lane id="E7_2" speedRelative="0.46"/>
        </edge>

The implementation of #1145 is not complete. The biggest obstacle is https://github.com/eclipse-sumo/sumo/issues/16302

In dense traffic, the speed estimation sometimes fails and vehicles on the slow lane do not collect enough incentive for attempting to change which is not how the model is supposed to work.

regards,

Jakob

Am Do., 22. Okt. 2026 um 17:11 Uhr schrieb Ni Ying-Chuan via sumo-user <sumo-user@xxxxxxxxxxx>:

Dear SUMO team,

 

I am trying to create a highway on-ramp traffic simulation scenario.

Attached please find the package.

 

The objective is to produce homogeneous congestion across multiple lanes as much as possible.

The problem is that the default parameter setup is not able to achieve this. If there is an on-ramp downstream, what we see is that the right lane would be congested because of lane changing from the ramp to the right lane, while no vehicles change from the right lane to the left lane so that the left lane is mostly in free-flow state.

 

I tried my best to tune the parameters by

- setting large time gap tau to allow more possibilities for lane changing and avoid collisions

- setting lcSpeedGain and lcAssertive to encourage lane changing

- making sure the upstream edge is long enough to accommodate lane-changing behaviors instead of vertical queues

 

We see improvements, but the left lane is still only intermittently congested, not very often.

 

Is there any way to ask vehicles on the left lane to slow down (yield) when there is a lane-changing requests from the right?

I also think this is what happens in the reality.

 

I appreciate it if you can share with me some tips or insights about how to encourage more lane-changing or increase its possibility.

Thank you very much.

 

Kind regards,

Ying-Chuan

 

--------------------------------

Ying-Chuan Ni

Email: ying-chuan.ni@xxxxxxxxxxxxxxxx

 

Traffic Engineering Group (SVT)

Institute for Transport Planning and Systems (IVT)

ETH Zurich

 

HIL F 37.3, Stefano-Franscini-Platz 5,

8093 Zurich, Switzerland

 

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