faq 34045984

Can we add a capacity limit for the nodes? and if yes how does it effect the results of the simulation?

by Kai Nagel on 2015-08-30 11:33:16

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On 01 Aug 2015, at 18:25, Deema F. Allan <dfallan@masdar.ac.ae> wrote:

Dear All,

   I have a quick question, Can we add a capacity limit for the nodes? and if yes how does it effect the results of the simulation?

Best Regards,

Thanks

Deema

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Comments: 2

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Re: Can we add a capacity limit for the nodes? and if yes how does it effect the results of the simulation?

by Kai Nagel on 2015-08-30 11:51:44

Dear Deema,

No, at this point you can't, at least not with the standard qsim. All capacity limits are on the (ends of the) links.

We have in mind to eventually make nodes and links replaceable, then you could replace the nodes logic.  But this is not so easy, because the qsim is not terribly modular (in part because it is quite ancient; in part because otherwise a fast computing logic is difficult to achieve).

If you _really_ need this _right now_, you could probably replace the QNetsimEngine as a whole.  If you need this (and you know enough Java programming), pls let us know and we will let you know the syntax (somewhat similar to matsim.org/javadoc --> main distribution --> RunMobsimWithMultipleModeVehiclesExample ).  

A (probably better) alternative would be to self-program some internal adaptive signal.  I.e. the intersection would count how many vehicles traverse and eventually set all corresponding traffic lights to red.  An example how to self-program an adaptive signal is (as of the next complete build) under matsim.org/javadoc → main distribution → RunSimpleAdaptiveSignalExample.

Best wishes

Kai

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Re: Can we add a capacity limit for the nodes? and if yes how does it effect the results of the simulation?

by Thibaut Dubernet on 2015-09-01 08:45:52

As a lightweight solution/hack, I would try generating "dummy" links for each node in a new network.xml. Intuitively, I would say one can get close enough to node capacity with this approach, setting maximum flow and capacity wisely (for capacity, you might have to play with length. Not sure the length of a vehicle is documented somewhere, so some code analysis would still be necessary).

 

I did not try it, but it definitely requires much less work than trying to implement a new mobsim.