[sumo-user] vehicle birth rate when defining flow rate using vehsPerHour

[Sharon Hornstein <sharon.hornstein@xxxxxx>]

 

Dear all,

I am running a merge scenario of two highway lanes that merge into one.

I have two flows of cars that are defined in *.rou.xml file (the content of the file is below).

I have 2 types of cars that are born on the top lane:

• “Human1” with vehsPerHour=1800
• “Controlled” with vehsPerHour=200

There is 1 type of cars that is born on the bottom lane:

• “Human0” with vehsPerHour=500

 

So the total flow in the top lane is 2000 vehsPerHour. I work with a time step of 0.5[sec].

The theoretical rate that I expect to have the cars born is 3600/2000 = 1.8[sec]. so due to the discretization I expect to have the cars born each 1.5 or 2 sec.

 

However, I run a 750[sec] long simulation (1500 time steps) and I realized that the rate of the cars that are born is inconsistent with the rate that I want.

• In the first ~100 seconds, the cars are born each 1.5 to 2.5 sec (very few cars are born each 1.5 sec, most of them at each 2sec, and some at 2.5sec)
• When the simulation progresses, the rate is decreased -> the time at which new vehicles are born becomes longer, each 3-3.5 sec and even longer.

 

I am trying to understand why I can’t get the cars born at the desired rate.

 

Thanks,

Sharon

 

 

The is the routes.rou.xml file

<routes>

    <route id="left" edges="left right"/>  

               

                <flow id="human1" route="left" type="human" begin="2" departLane="1" departSpeed="10" maxSpeed="30" end="90000" vehsPerHour="1800"/>

               

                <flow id="human0" route="left" type="human" begin="2" departLane="0" departSpeed="7.5" maxSpeed="30" end="90000" vehsPerHour="500"/>

                               

                <flow id="Controlled" route="left" type="Controlled" begin="2" departLane="1" departSpeed="10" maxSpeed="30" end="90000" vehsPerHour="200" color="1,0,0"/>                           

               

</routes>

 

This is a screenshot of the simulation, vehicles are born on the left hand side, and drive towards the right hand side.

At t= 42.5[sec]

 

At t= 199[sec]