VERIFIED SOLUTION i
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Resolve Roundabout gridlock in Paramics model

Issue

Vehicles gridlock around a roundabout, causing the whole network to seize up. All the gridlocked vehicles seems to be in Braking mode, at zero speed, with a tiny target headway that’s much less than their actual headway, but the program logic won’t let them inch forward to make space for the vehicle behind to exit the roundabout.

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Cause

This could be caused due to the fact that when links are short, vehicles can become confused as to which link they’re on, causing unrealistic behavior (stopping on a roundabout when/where there is no need to) which causes the gridlock (or the repeated circling of a roundabout).

Resolution

UPDATED: October 5, 2017


This is identified as a defect in Paramics and not fixed hitherto. Following workaround can be tried:
  • Set the headway factor low on the roundabout links so as to encourage the vehicles to bunch up
  • Add roundabout in spatial tests.
  • Replace the smallest roundabouts with all-way give-ways.
  • Lengthen the links on the circulating carriageway of those roundabouts that we’re modelling as a set of give-way junctions (more distance on the link red-to-white, less distance at the nodes white-to-red).
If the issue still persists, contact client support.

Environment Details

Product Feature: Modeller

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