emergency braking before roundabout in subsecond simulation

[namdre]

somewhat similar to #13290:

• vehicle A and B approach the roundabout from different arms with the same speed and distance (B enters upstream of A)
• both commit to enter at the same time and start to accelerate
• vehicle A must yield to B which has priority inside the roundabout and performs emergency braking

[namdre]

a possible solution (also for #13290) would be to treat committed vehicles in the same way as junction leaders even before they have entered the junction.

[namdre]

while using junction leaders has the structural advantage of working with the current right-of-way matrix, it still doesn't solve the problem: the approachInformation only becomes available in the next step after both vehicles have stated to accelerate.
The only mechanism that can resolve simultaneous decisions during planMove is MSLink::opened during executeMove

[namdre]

diff.workOn13292a0.txt
diff.workOn13292a.txt

diff.workOn13292b.txt (some attempt for handling this as a reference). Note: trying to add to external vehicles to the anyVehicle-iteration fails in subsequent code via getBackPositionOnLane.

[namdre]

in iTETRIS_acosta/no_internal_links, this is actually causing a collision: both vehicles start accelerate while already close to the roundabout. In the next step, they are unable to stop and the upstream vehicle crashes.

[namdre]

The problem stems from #1847 (842eec6): vehicles on approach to a roundabout that have gone past the visibility distance still don't put in a request for the next downstream link. There are two cases that would need to be distinguished:

1. the upstream vehicle actually starts to accelerate because it may enter the roundabout (request is needed to avoid downstream collision)
2. the upstream vehicle must wait for a vehicle within the roundabout (no request should be given so that a downstream vehicle may enter))