faq 109406144

Problem with bus and tram congestion when downsampling

by Renan Grace on 2017-05-15 04:25:28

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Hi all,

We have discovered some unusual behaviour in our model when downsampling with pt. We are running v0.8.1 and have tried 1% and 25% runs with pt. I have noticed that pt vehicles are all designated as car, which I understand is a known issue from searching in this forum and looking at the MATSim community space.

To illustrate our problem, take a one percent run as an example. We have a road which has a capacity of 600 pcu. It also has eight trams per hour on it, mixing with general traffic. When we downsample to one percent, we get an hourly capacity of 6 pcu (flow) and 18 pcu for storage (using capacity factors of 0.01 and 0.03 respectively). However, we still have eight trams per hour using the link, which means they completely block the link. This is happening all over our network and causing bottlenecks everywhere. This causes cars and pt users alike to be stuck on the network all day. The problem is not as severe for 25% samples, but the same issue exists.

I was wondering if anyone else has come up against this problem and knows of a neat solution?

Thanks in advance.

Renan.

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Comments: 3

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Re: Problem with bus and tram congestion when downsampling

by Renan Grace on 2017-05-15 22:47:40

Hi - I think I've found a solution to this problem at this link - see Kai's comments (thanks to Zahra Navidi for the tip). The solution is to change the passengerCarEquivalent of transit vehicles in the transitVehicles.xml input.

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Re: Problem with bus and tram congestion when downsampling

by Kai Nagel on 2017-05-18 16:09:35

Some other people had similar problems, and there is now a setPcuThresholdForFlowCapacityEasing in QSimConfigGroup (so far only in code, not via config.xml).  I hope that they will get back to you with explanations.

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Re: Problem with bus and tram congestion when downsampling

by Michal Maciejewski on 2017-05-21 22:02:11

Hi Renan,

Please have a look at this short report: https://www.researchgate.net/publication/317039686_MATSim_simulations_in_the_Tel_Aviv_Metropolitan_Area_Direct_competition_between_public_transport_and_cars_on_the_same_roadway

It describes some problems related to downsampled scenarios and PT. It also shows how to set up vehicles PCUs. Finally, it looks into the new feature called flowCapacityEasing that reduces the chances of buses being severely delayed. How to enable this feature: If for instance, buses have pcu of 0.3 and private cars of 1.0, then pcuThresholdForFlowCapacityEasing should be set to 0.3.

This is still an ongoing research. Right now we are evaluating the improvements resulting from the flow capacity easing. So far the results are very positive.

Hope that helps,

Michal