Re: [sumo-user] Regarding average speed in Edge based traffic measures

I have rechecked all my edges, and all the units are in m/s. The simulation scenario is for 39600-time steps, where initially vehicles enter from one edge and get out at another, travelling with maximum allowable speed but only using some of the edges of the network. After about 3600 timesteps, a few more vehicles enter, but now they use all the edges and may slow down or stop based on traffic conditions. In this scenario, the average speed for initial 3600 timesteps, the average speed is around 3-4m/s, while after 3600, it goes up to 7-8m/s, which I find counterintuitive. Hence I tried matching it with edgeData file values.

On Thu, Dec 22, 2022 at 2:04 PM Jakob Erdmann <namdre.sumo@xxxxxxxxx> wrote:
This sounds like a km/h vs m/s mismatch. If you define your edges with 16km/h than the average speed would typically be a bit lower i.e. ~14 km/h (due to random slow-downs and interactions of vehicles with different desired speeds). This would then be presented to you by sumo as ~3.8 m/s .

Am Do., 22. Dez. 2022 um 06:45 Uhr schrieb 191 000 <rohanverma446@xxxxxxxxx>:
Dear community,
Regarding the previous discussion on average speeds in SUMO, I have encountered another setback. Earlier I was using SUMO-GUI to generate a graph of the average speed of the whole network (at 5-minute intervals) and save it as a CSV file. Then I thought that if I got aggregated average speed of all the edges in the network, it should be equal to the values obtained from SUMO-GUI, but this is not the case. Could you explain how the average speed for the whole network is calculated and how I can get the same values through the edgeData file?
I wanted to compare these values as even though I had a max allowable speed of 16 and the vehicles were free-flowing, the average speed in SUMO-GUI would be around 3-4.
Thanks and regards,
Rohan

On Tue, Dec 13, 2022 at 2:11 PM Jakob Erdmann <namdre.sumo@xxxxxxxxx> wrote:
The speed value is computed as travelledDistance / sampledSeconds.
You should be able to replicate the aggregated speed value by the following procedure:
- for each edge compute travelled distances as speed * sampledSeconds
- sum up  the distances and sampledSeconds
- take the quotient of the sums

Am Di., 13. Dez. 2022 um 09:23 Uhr schrieb 191 000 <rohanverma446@xxxxxxxxx>:
Dear community,

I have been trying to understand how the average speed is calculated in edge-based traffic measures. I know it is space-mean speed but I am trying to aggregate data for multiple edges.
I first generated average speed of two edges using edges="" and aggregate="True" method, then I generated average speed of the two edges separately. Now, I have tried arithmetic mean, harmonic mean, weighted average by numbers but cannot get the value equal to the aggregated value given by SUMO.
Kindly suggest in what way can I manually aggregate the average speed data so as to get same value as when being done by aggregating directly through SUMO.

Thanks and regards,
Rohan
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