| Re: [sumo-user] Arriving to a traffic break-down and observing dynamic shockwaves ( / phantom traffic jams) |
_______________________________________________Thanks for the answers!I have succeeded to run just "krauss_t0.9_s1" and "krauss_t0.9_s0.8" test cases. Can it be that the rest of the cases are damaged or should I edit the files somehow?This is what I get when I try to run them:Dvirבתאריך יום ו׳, 6 במאי 2022 ב-17:33 מאת Jakob Erdmann <namdre.sumo@xxxxxxxxx>:1. Your question implies a bigger question: How realistic is a spontaneous break down of the flow (that is, without any external influence such as bottlenecks to trigger it)?. Some researchers are of the opinion that this is a very rare occurrence. Going by that line of thinking, the scenario will never be realistic. You can find additional test case (including multiple-lane setups) in https://sumo.dlr.de/extractTest.php?path=sumo/cf_model/fundamental2. that scenario has extremely dense traffic (to increase the likelihood of spontaneous breakdown). Dense traffic tends to look "clean" because each driver is tightly restricted by it's environment. Also, small speed variations are hidden by the scale of the plot (you should see them when zooming in). In the scenario linked above you will find some that have more varied plots3. The edgeData output used to generate the density data for a fundamental diagram averages over full edges. When using longer edges, this would hide small break-downs by averaging them with undisturbed sections. The choice of edge length does not influence the fcd-based plots.regards,Jakob_______________________________________________Am Fr., 6. Mai 2022 um 15:10 Uhr schrieb dvir n <dvirer@xxxxxxxxx>:_______________________________________________
Thank you very much for your answer Jakob, you helped me a lot!
I have 3 more questions:
1. I have noticed that the attached test case which consists of a 1 hour 3000 veh/hr flow along 20 km of road performs just a single shock wave. Is it considered to be a realistic scenario? If not - what can be done to make it more realistic? Which Vtype (or other) attributes do you recommend to edit in case of a 2 lanes scenario?
2. I used the SUMO plot_trajectories tool and noticed that the graph looks very clean and maybe less realistic. How can I improve it?
3. What is the reason that the road is divided into 100 sections? Can it affect the simulation results?
Sincerely, Dvir
בתאריך יום א׳, 3 באפר׳ 2022 ב-1:52 מאת Jakob Erdmann <namdre.sumo@xxxxxxxxx>:Hello,you can download a test case that shows breakdown of flow atThe test case collects traffic data which can be used to plot a fundamental diagram withsumo/tools/visualization/plotXMLAttributes.py edgedata.xml -i id -x density -y left -s --scatterplot --yfactor 60 --ylabel vehs/hourIt's pretty hard to observe spontaneous breakdown on a straight road because the disturbances travel upstream and take a while to develop into a full jam. For this reason the test uses 20km of road.regards,JakobAm Fr., 1. Apr. 2022 um 14:02 Uhr schrieb dvir n <dvirer@xxxxxxxxx>:Hello,I am trying to generate a realistic scene of a traffic break-down which is followed by many dynamic moving shokwaves in various lengths and speeds.In order to reach that road condition, I have modeled a simple 2 lane 4 km long straight road and inserted a high traffic flow (more than 2000 veh/hr/lane). However, no real serious shokwaves were observed.I was trying different car-following models which SUMO offers and edited their and the general Vtype attributes values. I have even decreased simulation time-step to 0.001 sec but still didn't succeed although high traffic values were observed (for example: Qmax = 2250veh/hr/lane, Km = 24veh/km, Vm = 94km/hr ).I will be glad to hear any suggestions for solving this problem and observing shockwaves which are caused just by the high density of vehicles in the road and not by an artificial interference such as adding ramp-in / generating a bottleneck / changing one car's speed or the road's shape / inserting non realistic Vtype's attribute values etc.Sincerely,Dvir_______________________________________________sumo-user mailing listTo unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/sumo-user_______________________________________________sumo-user mailing listTo unsubscribe from this list, visit https://www.eclipse.org/mailman/listinfo/sumo-user
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