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Re: [sumo-user] Macroscopic traffic flow - is it possible with SUMO?
The main point of SUMO is simulating individual vehicles. One of the problems that needs to be solved for that is to figure out which routes they use to reach their destination. MAROUTER is tailored to figure this out quickly but still it's end goal is to allow simulation of individual vehicles.
If you are only interested in a macroscopic view of traffic you are facing some limitations
- the constraint function is pretty hard-coded. As you saw it's a big switch statement based on speed limits and road priority. Thus, you may not be able to configure everything you want outside the code
- SUMO-GUI is not designed towards showing macroscopic traffic data. The mainly intended work-flow is to use the MAROUTER results fo a microscopic simulation

However, you can use MAROUTER and SUMO-GUI in a purely macroscopic way as is now documented at http://sumo.dlr.de/wiki/MAROUTER#Macroscopic_Outputs

regards,
Jakob

Am Do., 13. Dez. 2018 um 00:20 Uhr schrieb Michał Lis <johny1614@xxxxxxxxx>:
- What gives me that impression? docs says: " MAROUTER computes a macroscopic user assignment". Actually I should say creates flow between those zones. Zones are created by converting from
polygon by script edgesInDistricts.py. File generated by marouter has flow tags with properties like fromTaz, toTaz.
- About capacityConstraint I guess we think about the same thing :)
- Chunks... I feel like in a normal sumo microscopic aproach it's the same. I don't see 10 or 15 cars starting their trip in simulation like it would be a chunk.

Thanks for reply, still don't know though if I should give up trying simulate it with sumo, couse I feel sumo is a great tool but not for the thing I want - do something with respect of macroscopic flow.

wt., 11 gru 2018 o 10:44 Jakob Erdmann <namdre.sumo@xxxxxxxxx> napisał(a):
- What gives you the impression that MAROUTER creates assignment zones? The zones are read from the input using the option -d (--additional-files).
- The capacityConstraint function computes travelTime for that edge taking into account capacity constraints.
- Using the default 'incremental' method, the vehicles are assigned in chunks (total flow per OD-relation divided by number of iterations, default 20). The more vehicles that have used a link the slower it gets and this can lead to the assignment of fewer vehicles in the next step of the iteration. Vehicles always take the fastest route using the known capacities in their iteration step.

regards,
Jakob

Am Mo., 10. Dez. 2018 um 19:47 Uhr schrieb Michał Lis <johny1614@xxxxxxxxx>:
Thanks for the reply.
As I've observed - MAROUTER creates those traffic assignment zones and routes between them.
Every edge has a capacity defined by a getCapacity function (based on roadclass and length etc.).
Capacity constraint function is used to calculate travel time if we would like to travel on this edge (it is based on road's capacity, flow, speed limit etc).
This name confuses me - like shouldn't it be "getEdgeTravelTime" instead? Or is it a constraint actually on travel time because of capacity contraints?
Function incremental for all edges calculates travel times and attaches to it.
If im not mistaken we take the best route by cost which depends mainly to travel times of the edges - same as water or gas would choose way to spread.
In the end we still count each vehicle separately but direct them basing on those kinda macroscopic calculations from above? Is that the whole idea?

pon., 10 gru 2018 o 08:06 Jakob Erdmann <namdre.sumo@xxxxxxxxx> napisał(a):
Hello,
MAROUTER uses a hard-coded capacity-constraint function based on speed limit, lane number and edge priority to compute traveltimes and flows based on density.
For details, see
src/marouter/ROMAAssignments::capacityConstraintFunction
src/marouter/ROMAAssignments::getCapacity

MAROUTER reads OD matrices and creates route files. These route files contain route distributions between traffic assignment zones. Each route in the distribution is a fully specified list of network edges.

regards,
Jakob

Am Mo., 10. Dez. 2018 um 00:29 Uhr schrieb Michał Lis <johny1614@xxxxxxxxx>:
Hi. I need to use macroscopic traffic flow model - it is necessary for some mathematical calculations. I have read in FAQ that sumo supports "macroscopic traffic assignment" using MAROUTER. I feel like this doesn't mean that I have full macroscopic model with elements like density, flow based on density etc. Am I right? After proceeding everything from documentation with MAROUTER I get traffic assignment zones, is this the point of  "macroscopic traffic assignment" support?
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