Re: [sumo-user] Car Following parameters - "Tau"

[Michael Behrisch <oss@xxxxxxxxxxx>]

Hi,
you should always use departSpeed="max" when trying to maximize flows. 
Also I assume there may be a strange interaction with your acceleration 
an deceleration values. When defining the vtype and the flow like this 
it works as expected when changing tau:

    <vType id="TV" vClass="passenger" length="5" carFollowModel="CACC" 
tau="1.0"/>
    <route id="r1" edges="e1 e2 e3"/>
    <flow id="tvflow1" type="TV" begin="0" end="3600" vehsPerHour="2700" 
from="e1" to="e3" departSpeed="max"/>

Best regards,
Michael

Am 2019-07-24 22:35, schrieb Soumya Sharma:
> Hello,
> I am working with the CACC model to determine how it impacts freeway
> capacity. I studied in detail the algorithm for the CACC (
> https://www.sciencedirect.com/science/article/pii/S0968090X14002447?via%3Dihub
>  and
> https://www.sciencedirect.com/science/article/pii/S0968090X1830528X?via%3Dihub).
> In addition, I looked at the code at (
> https://github.com/eclipse/sumo/blob/master/src/microsim/cfmodels/MSCFModel_CACC.cpp
> ).
> However, I was not able to see how the time headway shown in two papers 
> is
> implemented in the code. I am particularly interested in decreasing 
> this
> parameter. I did try to work with "tau", however, it is still not clear 
> how
> "tau" is implemented in the CACC.
>
> Interestingly, when I set "tau = 1" it gives me the maximum flow. Any 
> value
> greater (1.5, 2) or lower (0.1, 0.2, 0.3, 0.5) than 1 decreases the 
> flow
> rate per hour. Could you let me know how timeHeadway is implemented in 
> the
> CACC model and also what parameter should I change if I want lower time
> headways (for example I want to have a time headway of 0.5 sec between
> vehicles).
> I have attached my files for reference.
> Thank you in advance.
>
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