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eclipse-sumo / sumo

Eclipse SUMO is an open source, highly portable, microscopic and continuous traffic simulation package designed to handle large networks. It allows for intermodal simulation including pedestrians and comes with a large set of tools for scenario creation.
https://eclipse.dev/sumo
Eclipse Public License 2.0
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Emergency braking in subsecond simulation #5632

Open levente-s opened 5 years ago

levente-s commented 5 years ago

Observed in 1.2.0 and in the latest development version.

In the attached example simulation, more than 300 emergency braking events occur (simulation time is about 2.5 hours with 2000 vehicles). sim.zip

sumo -n net.xml -r rou.xml --step-length 0.1 --no-step-log

with --step-length 1 there is no emergency braking

namdre commented 5 years ago

braking is due to the no-block heuristic (https://sumo.dlr.de/wiki/Simulation/Intersections#Junction_Blocking). This is supposed to avoid emergencyBraking but apparently some checks do not take subsecond simulation into account.

namdre commented 5 years ago

A few instances of emergency braking still occur (5 instead of 311). These still need to be investigated.

namdre commented 5 years ago

braking occurs when the vehicles does not wish to pass a link and computes vWait using stopDist x but there is a subsquent leader which forces stopping earlier due to minGap constraints. In execute move, it is taken for granted that subsquent driveItems will not force a lower speed if the vehicle stops beforing reaching those items.

Domsall commented 3 years ago

I thought I'll add it here, because it belongs to the topic of emergency braking on junctions: I have vehicles which wait on a junction to turn. Everything is fine until the foe vehicle drives onto the junction. The "ego" vehicle, wanting to turn, then already starts to drive although the junction is not free. It then brakes hard and waits again. It seems that the ego vehicle looses the foe vehicle for a short time and then sees it again.

Minimal Example: JunctionBraking.zip

namdre commented 3 years ago

@Domsall I moved your report to #8504 since this ticket is about the 'do-not-enter-the-junction-if-there-is-a-downstream-jam'-heuristic whereas yours seems to be an issue with the right-of-way logic

namdre commented 5 months ago

braking occurs when the vehicles does not wish to pass a link and computes vWait using stopDist x but there is a subsquent leader which forces stopping earlier due to minGap constraints. In execute move, it is taken for granted that subsquent driveItems will not force a lower speed if the vehicle stops beforing reaching those items.

The problem with subsequent drive-items having a lower speed was solved for a pedestrian related issue in c4c047e (#14919)