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# Congestion on the road

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Hello,

I want to simulate an evacuation network problem. When a hurricane is imminent, all people want to evacuate the hazard area to safe areas. Therefore, we have a traffic jam (congestion) on the road. So, The speed of vehicles changes based on traffic. I have a couple of questions:

1) Is there any module in the Simio to consider traffic on the road instead of considering waiting time for server or transfer node. I mean that congestion embedded on the road by decreasing the speed of entities.

2) Are there any options to consider congestion such as considering a segment of a road is decomposed into cells based on the free flow velocity and length of discrete time step. By this division, vehicles can move only to adjacent cells in unit time. The connectors between cells are dummy arcs indicating the direction of flow between cells. For example, if 5 hour takes time to drive from the beginning of the road to the end, we put transfer node after each one unite of time (server---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> server ). In the path, vehicles drive with fixed speed and path has a fixed capacity. Therefore, we can consider congestion if a vehicle wait to enter the path.

I would be really happy if you could let me know how to consider congestion on the road.

Thanks,

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Check my attached model.

The entities have random movement speed and paths Allow Passing property are set to False. So slower entities will naturally create a traffic congestion.

You could also try to solve this in a more algebraic manner, by setting ModelEntity.DesiredSpeed or Path.DesiredSpeed based on the Path.Contents state.

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11 hours ago, Nadere said:

2) Are there any options to consider congestion such as considering a segment of a road is decomposed into cells based on the free flow velocity and length of discrete time step. By this division, vehicles can move only to adjacent cells in unit time. The connectors between cells are dummy arcs indicating the direction of flow between cells. For example, if 5 hour takes time to drive from the beginning of the road to the end, we put transfer node after each one unite of time (server---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> after 1 hour--> transfer node ---> server ). In the path, vehicles drive with fixed speed and path has a fixed capacity. Therefore, we can consider congestion if a vehicle wait to enter the path.

For your second question, you should use TimePaths instead of Paths. Just set the Initial Traveler Capacity and Travel Time properties to an arbritary number.