Re: [sumo-user] Questions about creating a capacity drop and lane-changi

[Jakob Erdmann <namdre.sumo@xxxxxxxxx>]

From the low spacing in your screenshot, I'm guessing that you are measuring inflow by the number of vehicles specified in the input file rather than by inflow into the simulation.

Most likely, you have delayed departures due to jamming on the inflow edge and are only ever simulating inflow of about 3000 veh/h.

The easiest fix would be to do the following:

- increase the length of the inflow edge

- set departSpeed="avg"

Check for the "departDelay" value in tripInfo-output or statistics-output to make sure your vehicles are actually able to enter. 

See also https://sumo.dlr.de/docs/Simulation/RoadCapacity.html

and https://sumo.dlr.de/docs/Simulation/VehicleInsertion.html

The counterintuitive spacing comes from the transition between jammed inflow and then free-flow at the merging point.

You can tune the distance at which zipper behavior starts with connection attribute visibility distance: https://sumo.dlr.de/docs/Networks/PlainXML.html#explicitly_setting_which_edge_lane_is_connected_to_which

regards,

Jakob

Am Mo., 15. Juli 2024 um 04:56 Uhr schrieb Xuanmian He via sumo-user <sumo-user@xxxxxxxxxxx>:

Dear SUMO Team,

I'm building a lane-drop bottleneck scenario and trying to create a capacity drop. I tried the 'priority' and 'zipper' modes for the junction, but both of them didn't perform the capacity drop even when demand greatly surpassed the capacity. Also, I turned 'speedDev' value to 0.05 and 'lcCooperative' to very low(0.2), as taught in SUMO documentation, but it still didn't work.

I adjusted the input flow rate and did the experiment. The relationship between the inflow of the network and the throughput of the bottleneck is attached. In my scenario, the bottleneck has 2 lanes and the upstream section has 4 lanes. After inflow exceeded 4000veh/h (i.e. 2000 veh/lane/h), throughput was expected to drop but it didn't.

Another question is about lane-changing behavior in front of a zipper junction. It seems that vehicles tend to keep a higher spacing for merging and start to accelerate about 100 meters in front of the merging point. How to make them wait and pass alternately only at the merging point?

I appreciate your help.

Best regards,

Xuanmian He

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