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faq 109093933
by Celeste Manu on 2017-04-25 22:23:55
How does MATSim choose the rate at which agents are released from a starting link if all agents are set to start at the same starting link at the same time? I understand that the default sim for MATSim is QSim, which has no maximum inflow capacity. However, the agents in my simulation which are all set to start their activity at the same time don't leave at the same time, even at iteration 0. Where can I find details on this? Thanks.
by Johan W. Joubert on 2017-04-26 05:26:32
Your other question is related, and you will find more information on the dynamics there.
There is a small, little-known variable in the QSim class called the simTimer, and it is of class type MobsimTimer. The default value is 1.0 second, and this is the interval that the mobsim will take to move from one incoming link to another to check for agents to let through the node, so to speak. Your starting link is one of those incoming links at a node. I would unnecessarily mess with that timer (we have in the past to get vehicle passing dynamics more realistic), but if you need to, or see what the effect is, you can do it in the config
Config config = get.it.from.somewhere();
config.qsim.setTimeStepSize(0.1);
with the value given in seconds.
by Marcel Rieser on 2017-04-26 06:18:14
QSim has—in its default configuration—an unlimited inflow capacity. But the agents starting their leg on a link are subject to the link's outflow capacity. When a large number of agents start their legs at the same time, they are all added to the "wait2link"-queue. From there, they are added to the link's "buffer" whenever the buffer as free space, and from there moved over the node to the next link. The "buffer" has a limited size to ensure the link's outflow capacity. So, even when all agents on a link start their leg at the same time, they can only leave the start link according to the start link's outflow capacity.
by Celeste Manu on 2017-04-26 17:30:36
A follow up question on this behavior. At the root of my more general questions is this behavior I'm trying to figure out. I have a large amount (hundreds) of agents set to leave certain nodes at the same time. The link capacities are all 6 cars/min. My network/simulation looks like the following after 1 minute. I can see that only 6 cars/min leave the nodes that agents start from, but shouldn't it be 6/min/link? not 6/min/node?
From the book and your answers, I would expect 6 cars per link traveling outwards. Would either of you have any insight into this behavior? Let me know if you need more details.Thanks a lot.
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