Yes. Using by using departPos="random_free", vehicles are inserted with lower speeds and slightly higher densities which makes the drop already appear without even setting lcCooperative. By setting lcCooperative you reduce the merging efficiency and thus increase the capacity drop.
regards, Jakob Am Di., 2. Apr. 2019 um 18:06 Uhr schrieb <[email protected]>: > Hello Jakob, > > Thanks very much for your reply. You are absolutely right. > > Now I have set the merging area with four lanes but the downstream > mainline with three lanes. Also, I have increased the input volume with the > attributes departPos="random_free" and departSpeed="max". I didn't changed > the default speed distribution but set the lane changing parameter > lcCooperative to "0.6". By doing so, it seems "capacity drop" has happened. > Am I on the right way? > > Best, > > Yu Tang > > > -----原始邮件----- > *发件人:*"Jakob Erdmann" <[email protected]> > *发送时间:*2019-04-02 21:28:39 (星期二) > *收件人:* "Sumo project User discussions" <[email protected]> > *抄送:* > *主题:* Re: [sumo-user] Question about reproducing the phenomenon "capacity > drop" > > Hello, > the answer to this is a bit complex, sorry. > > - capacity drop is negatively correlated with lane count in reality. With > default settings you should be able to see it if the main line has only 1 > lane (2 lanes in the merging section) > - capacity drop can only be observed if the entering flow of the mainline > is near the limit. In a small scenario this can be achieved with > vehicle/flow attributes departSpeed="max" departPos="last" > - however, using the default distribution of desired speeds (speed > deviation of 10% around the speed limit) you will still not get the full > capacity because sometimes a slow vehicle is inserted after a fast vehicle > and this creates gaps in traffic. When these gaps are filled at the on-ramp > this compensates for the capacity drop so you might actually see a capacity > gain.The capacity drop can be observed when setting the speed deviation to > a lower value (speeDev="0.05") and it grows stronger when setting it even > lower > - there is a known issue with the current dynamics model that can lead to > a strong separation of vehicle speeds between the lanes (rightmost lane is > very slow and leftmost lane is still at maximum speed). This lowers the > observed capacity drop effect because there is no spill-over jamming effect > to the left lanes. The speed seperation can be avoided with careful tuning > of the lane-changing gap acceptance parameter (lcAssertive) distribution > across the vehicle fleet but I anticipate that there will be model > extensions in the future to adress this. > > regards, > Jakob > > > > > Am Di., 2. Apr. 2019 um 09:27 Uhr schrieb <[email protected]>: > >> Hello, >> >> I am simulating the traffic in the merging area where vehicles come from >> the one-lane on-ramp and the three-lane mainline. I hope to reproduce the >> phenomenon "capacity drop" that means the discharge rate is less than the >> capacity in the downstream mainline. I have tuned some parameters but >> failed. >> >> Can anyone kindly informed me which parameters should be fine-tuned to >> simulate "capacity drop"? >> >> Thank you. >> >> Yu Tang >> _______________________________________________ >> sumo-user mailing list >> [email protected] >> To change your delivery options, retrieve your password, or unsubscribe >> from this list, visit >> https://www.eclipse.org/mailman/listinfo/sumo-user >> > _______________________________________________ > sumo-user mailing list > [email protected] > To change your delivery options, retrieve your password, or unsubscribe > from this list, visit > https://www.eclipse.org/mailman/listinfo/sumo-user >
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