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Re: [sumo-user] regarding change of allowed speed along a route
Hello Gerald,
there isn't really a decision tree for most of the speed decisions (except for a big one within the lane change model).
All of the potential influences are evaluated and the minimum allowed speed is used.
The page you found is an attempt to list all these influences and will be extended as needed (let me know if a particular situation is unclear or vehicles behave different from the expectation)
A list of recent amendments can be found at https://github.com/eclipse/sumo/commits/master/docs/web/docs/Simulation/VehicleSpeed.md

best regards,
Jakob

Am Do., 12. Aug. 2021 um 10:21 Uhr schrieb Richter Gerald <Gerald.Richter@xxxxxxxxx>:

Hi Jakob,


thanks for the answer.
clicking the link led me to a 404, so it must be https://sumo.dlr.de/docs/Simulation/VehicleSpeed.html


The vehicles are moving and they are controlled by algorithms, so

when assuming "things that happen" I was (exemplarily) thinking about:

  • vehicle is created at entry point (edge)
    placement depends on:
    • gap to leader on 1st lane
      (e.g. rightmost / leftmost depending on roadside driving convention)
    • if gap too small check 2nd lane
      ... and so on
  • vehicle attributes are set up
  • vehicle approaches junction
  • vehicle crosses into another edge
    • speed limits have changed
  • vehicle crosses onto junction
  • vehicle hits a re-routing trigger point
    ... this happens
  • vehicle receives another desired speed
  • ego approaches leading vehicle, falls below minimum headway gap

So as I see on the docs page you pointed me to,
this contains some of the information - here wrt. speed choice - that I was lining out above.

I simply often wondered "what will a vehicle do in this or that a case" and 
"do I have to or may I intervene by using traci",
when constructing some potential scenario of interest.
and I thought such a rough procedural overview on the decision sequence / tree might help.

thanks again,
best regards
Gerald.

Von: sumo-user <sumo-user-bounces@xxxxxxxxxxx> im Auftrag von Jakob Erdmann <namdre.sumo@xxxxxxxxx>
Gesendet: Donnerstag, 12. August 2021 08:28:17
An: Sumo project User discussions
Betreff: Re: [sumo-user] regarding change of allowed speed along a route
 
Hi Gerald,
exactly nothing happens along the way hence there is no documentation for this.
The speedFactor is picked at vehicle creation and remains constant over the life cycle. Being a unit-less value (typically ~1), it will be applied to every speed limit along the way when computing the maximum desired vehicle speed.

The only way to change vehicle attributes is via TraCI or type-calibrators.
A list of everything that can influence vehicle speed is at https://sumo.dlr.de/docs/Simulation/VehicleSpeed.htm

regards,
Jakob

PS: vehicle-class specific speed limits that were discussed in that email have since been implemented (and are strongly recommended when simulating a bimodal speed distribution for trucks and cars).



Am Mi., 11. Aug. 2021 um 18:10 Uhr schrieb Richter Gerald <Gerald.Richter@xxxxxxxxx>:

hi all,


to my understanding, when a vehicle enters the simulation stage,
it is randomly given a certain speed factor
that relates to the max allowed speed and
will lead to a desired velocity slightly below or above the lane limit.


what happens, when the allowed speed changes along the route?
I found this old communication:
https://sourceforge.net/p/sumo/mailman/message/27058304/

but would like to ask again.


  • is the speed factor re-shuffled in such a case?
  • are there any other cases where it is re-shuffled?

is there a rudimentary documentation (apart from the source code) 
which describes the life-cycle of a vehicle and what wondrous things might happen along the way?

thanks, best regards
Gerald.


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