faq 109402318

Reducing the capacity of a few links to simulate a hypothetical scenario

by Sashi Gurram on 2017-05-14 17:21:53

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I am trying to simulate a hypothetical scenario which uses the base year's highway network in conjunction with the future year's (improved) bus transit schedule. However, due to some practical constraints, I am unable to simply merge the base highway network and the future transit schedule. So, I am forced to use the future year's highway network along with the future year's transit schedule. Obviously, the future year's highway network has more links compared to the base year. Fortunately, I do have some understanding on which of these links in the future year's highway network are new compared to the base case.

Given this, can I achieve similar results like the base highway+future transit if I were to reduce the capacity of these links (to lets say an adhoc value of 10) and indicating that only buses can go on these links? Will this make sure that no cars (or other modes like ride, school bus, bicycle) will use these links? I am thinking of something like below. SO, the network file is the only file that I am making changes to. Please let me know if you foresee any issues with the way I am setting this up or if you have any alternative suggestions.

<link capacity="10" freespeed="20.1168" from="12884" id="128841064" length="313.255374069" modes="bus" permlanes="1" to="1064"/>

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Comments: 1

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Re: Reducing the capacity of a few links to simulate a hypothetical scenario

by Kai Nagel on 2017-05-18 15:58:53

In theory this should work as you say.  

In practice, it looks like this will not work as advertised.  See JIRA (matsim.atlassian.net)39b78b4e-5e5e-31ca-ad6c-6e03846a9bf5MATSIM-533.  I don't think that this has been resolved, despite the link to MATSIM-504 and the "resolved" tag there.

However, "not work as advertised" may not mean that it will fail.  In practice, the mobsim does not check the modes, albeit it should (see https://github.com/matsim-org/matsim/blob/master/matsim/src/main/java/org/matsim/core/mobsim/qsim/qnetsimengine/QNode.java , method checkNextLinkSemantics).  

So it may, after all, work as you say, but for the wrong reasons.

Not good, I am sorry.  But it is the way it is.