Re: [sumo-user] Macroscopic Fundamental Diagram (MFD)

[Qichao Wang <qichao@xxxxxx>]

Hi Royal,

Note that a fundamental diagram is usually generated from one detector to represent the dynamics of a stretch of a road while Network/Macroscopic Fundamental Diagram is usually aggregated from many detectors over a network. The  fact that a network can have a well-shaped Network Fundamental Diagram partially depends on the fact that the drivers are smart and can avoid congestion. An arterial may or may not give you a nice looking MFD (if MFD is what you are looking for).

However, if you just want to get the capacity of your link, you can simply keep increasing your input flow until your output flow stops increasing (and the maximum output flow rate is your capacity). 

Thanks,

Qichao

On Wed, Jan 19, 2022 at 7:40 AM Royal Bhandari <royalbhandari6@xxxxxxxxx> wrote:

Hello,

I am dealing with an urban section that has intersections and I also have real-world counts (through movements and turning movements). How do I calculate the capacity of the road segment (let's say from point A to B).

See attached pic for your info. The red line represents the segment I am interested in. The blue lines are the intersections where I have provided turning probabilities.

Regards,

Royal

On Wed, Jan 19, 2022, 00:46 Jakob Erdmann <namdre.sumo@xxxxxxxxx> wrote:

For a straight road segment without intersections the main determinant for flow is the insertion capacity. See https://sumo.dlr.de/docs/Simulation/RoadCapacity.html

However, In an urban setting it's likely that the real-world capacity is impacted by intersections so the simulated capacity for a straight road segment will overestimate real-world capacity.

If you are mainly interested in the capacity and you do have counting data, you could simply use the maximum recorded flow and be done with it.

Am Mi., 19. Jan. 2022 um 06:55 Uhr schrieb Royal Bhandari <royalbhandari6@xxxxxxxxx>:

Hello Qichao,

Thanks for the reply. Can you please elaborate on a network that drivers can choose routes in? Does this mean I have to provide origin and destinations instead of predefined flows? And how can I create the fundamental diagram if I have a straight urban road segment with real-world flows?

Regards,

Royal

On Tue, Jan 18, 2022 at 11:49 PM Qichao Wang <qichao@xxxxxx> wrote:

Hi Royal,

Note that MFD is different from FD. To plot MFD (or someone may call it NFD), you need to have a network that drivers can choose routes in.

Thanks,

Qichao

On Tue, Jan 18, 2022 at 10:43 PM Royal Bhandari <royalbhandari6@xxxxxxxxx> wrote:

Hello,

I am trying to plot a MFD (density vs volume) in order to determine the capacity of my link. I went through the documentation of the fundamental diagram. It is of little help as it has only mentioned "Fundamental diagram of a closed circular route". 

I understand that in order to plot MFD I have to plot the values of flows for various densities. How do I provide density in an increasing order such that I can reach the maximum flow before the flow starts decreasing? Do I have to run the same simulations providing various flows and getting densities as output? Please help me out.

Regards,

Royal

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--

Qichao Wang, Ph.D.

Postdoctoral Researcher | Computational Science

Complex Systems Simulation and Optimization Group

Computational Sciences Center

National Renewable Energy Laboratory