collision with left-turning vehicle (trac #1096)

[behrisch]

It goes like this:

• left turning vehicle A starts to drive
• suddenly realizes it cannot pass the junction safely because of oncoming vehicle B with the same target
• A brakes but cannot stop
• A enters the junction slowly
• A is to slow when leaving the junction and vehicle B crashes into it
  (found twice in the the bs-scenario)

Migrated from http://sumo.dlr.de/ticket/1096

{
    "status": "closed", 
    "changetime": "2013-12-16T10:28:45Z", 
    "description": "It goes like this:\n- left turning vehicle A starts to drive\n- suddenly realizes it cannot pass the junction safely because of oncoming vehicle B with the same target\n- A brakes but cannot stop \n- A enters the junction slowly\n- A is to slow when leaving the junction and vehicle B crashes into it\n(found twice in the the bs-scenario)", 
    "reporter": "namdre", 
    "cc": "", 
    "resolution": "fixed", 
    "_ts": "1387189725074833", 
    "component": "microsim - junctions", 
    "summary": "collision with left-turning vehicle", 
    "priority": "major", 
    "keywords": "", 
    "time": "2013-12-06T14:05:00Z", 
    "milestone": "0.20.0", 
    "owner": "namdre", 
    "type": "defect"
}

[behrisch]

• @namdre committed 09ee1cc (aka r15310):
  decoupling stop-line offset from minGap to fix collision with left-turning vehicle (trac #1096) #1096
• @namdre changed resolution from "" to "fixed"
• @namdre changed status from "new" to "closed"

[behrisch]

@namdre commented:

due to subtracting minGap from the distance-to-junction in some computations, vehicles on minor links were often too fast to stop when reaching the final decision-point. In cases where a foe vehicles showed up just then, collisions could happen.

[behrisch]

@www-data committed 0ed500a (aka r15315):
now taking reaction time into account when estimating arrival speed if braking refs #1096

[behrisch]

@namdre committed 8745a5f (aka r15323):
patching expected result refs #21, #1096. The .net.xml file has unsafe connection states so the collision is expected

[behrisch]

@namdre commented:

finally fixed in 9976a65 (aka r15320). Links at internal junctios had state 'M' (major) even though vehicles need to be able to stop if foe traffic suddenly appears (this happens seldomly but was then causing collisions). If the link is controlled by a traffic light and has state 'G' (green major), vehicles pass the internal junction without slowdown as before.

[behrisch]

@www-data committed efb8397 (aka r15329):
ensuring that lastWasGreenCont works even when spread across multiple simulation steps. Before [15320] this code was not needed because these links always had state 'M'. in [15320] it was only working if the vehicle was passing both links in one step. refs #1096