Re: [sumo-user] Unequally spaced vehicles

[Jakob Erdmann <namdre.sumo@xxxxxxxxx>]

Hello,

This is an artefact of the simulation step-length (vehicles can only be inserted at full seconds and this implies a narrow choice of headways when inserting at a fixed position. (There is actually an open issue that would fix this https://github.com/eclipse/sumo/issues/4277)

- One workaround is the insert the vehicles with the attribute departPos="last" and departSpeed="x" where x is tuned to achieve the desired space headway based on the car-following parameters. However, this always results a fixed time headway according to the vehicle types tau parameter.

- Another workaround is to lower the simulation step-length somewhat

- A third approach would be to generate the vehicles individually with  a script and define the desired departPos for each one

regards,

Jakob

2018-08-30 5:41 GMT+02:00 Alan Dee <adandee.sumo@xxxxxxxxx>:

Hello,

I have needed an equally spaced vehicle flow. As per the documentation , vehicles should be equally spaced unless someone randomizes the flow. I didn't randomize the flow, but I am experiencing that the vehicles do not have the same headway. 

Here is my rou.xml file entry, and I set sigma = 0 as well.

<flow id = "f1" color="1,1,1"  begin = "0" type="Car" vehsPerHour="1500" number="100" route="route0" departSpeed="13.9"> </flow>

I am seeing majority of the vehicles have a headway around 27m and some other vehicles around 40m. There is a pattern. The first 2 vehicles of every 5 vehicles travel together (with 27m  heading), and other other 3 travel together (with 27m  heading) but with 40m gap between 3rd and the 2nd (e.g. V represents a vehicle V**V**V*****V**V*****V**V**V*****V**V**V**V**V*****V**V)

I tried this as well.  <flow id = "f1" color="1,1,1"  begin = "0" type="Car" period="2.4" number="100" route="route0" departSpeed="13.9">  </flow> 

But it is the same as the previous.

Is this is a bug or is there a workaround for this?

Thanks,

Dee.

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