Hi,
I have a question regarding dividing a set of SUMO route file flow definitions into different sub-time intervals. The purpose of dividing the flow definitions is to use the same flow elements and corresponding routing (from-via-to) throughout the simulation, but with the possibility of varying the vehicles per hour inserted for each sub-time interval.
Below, I provide an example of my original route file structure and how I divide the set of flow definitions into sub-intervals.
Originally, I have a route file structure as follows (to illustrate, in the below flow elements I have intentionally left out attributes: vehsPerHour, from, to, via, departLane and departSpeed)
<trips>
<vTypeDistribution id="vehType1" >
... definitions of various vType-elemets...
</vTypeDistribution>
<flow begin="0.001" end="10200" id="5" type="vehType1" />
<flow begin="0.001" end="10200" id="7" type="vehType1" />
<flow begin="0.001" end="10200" id="9" type="vehType1" />
</trips>
Say that I run a simulation using the above structure during a simulation time interval of [0, 2001] s. I would then like to create a route file providing me the same simulation results as for the structure above, but the set of flow definitions are repeated in several sub-time intervals.
I do this as follows:
<trips>
<vTypeDistribution id="vehType1" >
... definitions of various vType-elemets...
</vTypeDistribution>
<flow begin="0" end="1000" id="1" type="vehType1" />
<flow begin="0" end="1000" id="4" type="vehType1" />
<flow begin="0" end="1000" id="7" type="vehType1" />
<flow begin="1000" end="2000" id="10" type="vehType1" />
<flow begin="1000" end="2000" id="13" type="vehType1" />
<flow begin="1000" end="2000" id="16" type="vehType1" />
<flow begin="2000" end="2001" id="19" type="vehType1" />
<flow begin="2000" end="2001" id="22" type="vehType1" />
<flow begin="2000" end="2001" id="23" type="vehType1" />
</trips>
Note that for each sub-time interval (in my example: [0, 1000), [1000, 2000), [2000, 2001)) the flow definitions in the set (three in my example) are identical with respect to values of attributes vehsPerHour, from, to, via, departLane and departSpeed.
When running an identical simulation for [0, 2001] s using the above structure for my route file I notice the following three main differences in the simulation outcome compared to my original structure:
1. Difference in the simulation results (deduced from detector output) for the complete simulation.
I can image that the vehicle types drawn from my vehicle type distribution differ between the two ways of structuring my route file (e.g. the seed for drawing a vehicle type might be reused when going from sub-interval 1 to sub-interval 2 etc., such that the vehicle types that are inserted in the system differs between using the two route file structures).
Question 1: Do you think that is the reason?
Question 2: Can I define my set of flow definitions in sub-time intervals such that I obtain the same simulation results as using my original structure?
2. Difference in the simulation results for the initial interval [0, 1000) s.
I don't see how results from the first interval would differ for the different structures since the first interval shouldn't be subject to vehicle types begin drawn differently.
Question 3: Do you have any idea of why that is the case?
3. The time running the simulation increases significantly using the second structure dividing the flow definitions into sub-intervals.
Question 4: Is this expected?
(Note that in the actual simulations I run I have set of about 600 flow definitions divided into 23 sub-intervals containing my total simulation time).
Most importantly, it is "Question 2" that I am most eager to find out about!
Best regards,
Jimmy
