Re: [sumo-user] Flow definition disrepancy

[Chedly Bourguiba <chedly@xxxxxxxxxxx>]

Hi Jakob,

Thank you for your quick response.

We are currently defining the flows for one single time period, for one single intersection. We have specified the number of vehicles entering an approach (259). The approach has 5 lanes (2 for right turns, 2 for thru movements and 1 for the left turn). We have also defined the turning probabilities for left, thru and right. 

When we run the simulation, however, the output numbers are significantly higher for the thru movement lanes than expected (based on the number of total vehicles at the approach multiplied by the probability for the thru movement). In addition, the right turn movements and the left turn movements are close to what they should be. Consequently, the total number of vehicles at that approach is higher than the number we expect from the flow file. We're struggling to understand how this behaviour could be possible. We've checked that the flow number in the flow file and the turning probabilities in the turns file are correct.

Do you know any possible reasons why this should be happening? Let me know if you need any further information to diagnose.

Thanks,

Chedly

On Thu, Mar 5, 2020 at 10:52 PM Jakob Erdmann <namdre.sumo@xxxxxxxxx> wrote:

Hello,

The traffic demand given to SUMO typically does not specify the exact lane sequence. This means individual lanes could see higher flows and other lanes could see lower flow due to lane choice.

I would expect the simulated edge flow to be no higher than the defined flow.

An exception might happen if vehicles cannot be inserted for some time and then are released into the simulation at a later time, thereby increasing the flow beyond the specified value.

Things to check for:

- edge flow vs expected flow at different time aggregations

- depart delay (trip info), delayed departures per lane (gui coloring style)

- departLane definition for your flows

regards,

Jakob

Am Fr., 6. März 2020 um 01:52 Uhr schrieb Chedly Bourguiba <chedly@xxxxxxxxxxx>:

Hi,

I have an intersection where I know the exact vehicle count per lane and movement per hour (a specific hour). When running sumo, I define the flow XML file using the vehicle per hour attribute and then I compare the count I had for the specific hour that I modeled and some lanes would have a count higher than the value I used to model the flow.
Do you have any leads/idea where the discrepancy can come from?
Thank you in advance for your help!

Best,

Chedly

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