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Re: [sumo-user] edge-based traffic measures
Hello,

I somehow missed this email. I have attached a couple of pictures below to justify my confusion.

for edge -e1, samplesec = 1889.24, Period = 4499, density = 15.54. Hence, using the formula, length = samplesec/period * 1000/density = 27 m

However, the real length of the edge "-e1" is 31.45m, why is this discrepancy happening? Please let me know.



image.png

image.png

On Tue, Dec 21, 2021 at 4:37 PM Jakob Erdmann <namdre.sumo@xxxxxxxxx> wrote:
"2. period denotes the time period that was aggregated. By default it's the whole simulation time but you can change it with attribute 'freq'"

In your case, the aggregation period is 3600. It's always the same for all edges.

Am Di., 21. Dez. 2021 um 18:41 Uhr schrieb Royal Bhandari <royalbhandari6@xxxxxxxxx>:
Thanks for the reply. However, I am still confused with the period attribute.

In my case, (start time=0 sec, end time = 3600 sec), and I haven't specified any intervals. What would be the value of the period? And will be the value of period be the same or different for various edges of the same network?




On Tue, Dec 21, 2021 at 1:56 AM Jakob Erdmann <namdre.sumo@xxxxxxxxx> wrote:
1. at any given moment there is a total number of vehicles on an edge and this number varies over time. edgeData is a time-aggregate so you only get the average number of vehicles on the edge per second (computed as sampledSeconds / period).
2. period denotes the time period that was aggregated. By default it's the whole simulation time but you can change it with attribute 'freq'
3. based on edgeData alone you cannot get an unbiased aggregate since vehicles may briefly occupy two edges at the same time and are thus counted twice when summing edgeData. You can eithe accept this bias or do you own aggregation based on unaggregated data (i.e. fcd-output).

Am Di., 21. Dez. 2021 um 00:51 Uhr schrieb Royal Bhandari <royalbhandari6@xxxxxxxxx>:
Hello,

I have several questions regarding edge-based traffic measures:
  • What is the difference between the total number of vehicles on an edge and the average number of vehicles on an edge? (is av num of vehicle in an edge = num of vehicles in a particular edge/no of edges,  irrespective of the length of each particular edge?)
  • What is the value of the period in the attached figure if I simply have a single simulation with begin time = 0 and end time = 3600?
  • It is mentioned that "Spatial aggregation (over multiple edges or lanes) is not as easy". However, the process of doing this is not given. Please direct me to this.




image.png





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