faq 75268114

I would like to know how to fix these link error messages.

by Yousef Hindy on 2016-07-28 19:09:10

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So when I run my simulation, I am getting these errors: 

2016-07-28 12:06:22,128  WARN QueueWithBuffer:364 Link 1 too small: enlarge storage capacity from: 16.737935805466666 Vehicles to: 28.53057239568182 Vehicles.  This is not fatal, but modifies the traffic flow dynamics.
 2016-07-28 12:06:22,132  WARN QueueWithBuffer:364 Link 2 too small: enlarge storage capacity from: 56.6954206316 Vehicles to: 300.65753365242426 Vehicles.  This is not fatal, but modifies the traffic flow dynamics.

 

(they continue on for all links, but most of the warnings are suppressed). 

I am confused though, as in my network.xml file, I have the links defined as the following 

 

<link capacity="9000.0" freespeed="11" from="1" id="1" length="125.534518541" permlanes="1" to="2"/>
 <link capacity="28000.0" freespeed="11" from="1" id="2" length="425.215654737" permlanes="1" to="3"/>
 <link capacity="9000.0" freespeed="11" from="2" id="3" length="125.534518541" permlanes="1" to="1"/>
 <link capacity="25000.0" freespeed="11" from="2" id="4" length="381.142122176" permlanes="1" to="4"/>

 

Any help on how to fix this would be much appreciated!

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Comments: 1

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Re: I would like to know how to fix these link error messages.

by Pieter Fourie on 2016-07-29 00:45:34

Dear Yousuf,

 

If you read through the method org.matsim.core.mobsim.qsim.qnetsimengine.QueueWithBuffer.calculateStorageCapacity(),  you'll understand what is happening; the arithmetic is pretty straightforward. 

In short, your links have such high flowCapacity given their speed and length and number of lanes, that they allow more vehicles to pass through than what can be physically fit on the link.

The number of vehicles that can fit on a link = number of lanes * length / typical vehicle length (7.5m by default).

The typical flow capacity per lane for a signalled link (neighbourhood links) is approx 1000 veh/hr/lane; and twice as much for expressways and un-signalled links. 

So, for the flow capacities in your links, you need substantial increases in the number of lanes to have realistic capacities.