collisions because vehicles dawdle on the junction (trac #857)

[behrisch]

The recent changes in link management have increased junction efficiency by tightening the (sometimes excessive) safety buffers. However this creates problems if vehicles commit to driving across the junction and then suddenly decelerate due to dawdling (sigma > 0).

I see 2 ways to deal with this issue:

• add simulation parameters to control the safety margins while comitted / uncomitted (MSLink.cpp:154 and accept occasional collisions if these parameters are set to tightly or low flow if set to conservatively
• add an additional vehicle type parameter sigmaCritical (or somesuch) to use during critical situations. In my opinion this should default to 0 because people tend to concentrate during critical maneuvers

discuss!

Migrated from http://sumo.dlr.de/ticket/857

{
    "status": "closed", 
    "changetime": "2013-02-15T10:50:17Z", 
    "description": "The recent changes in link management have increased junction efficiency by tightening the (sometimes excessive) safety buffers. \nHowever this creates problems if vehicles commit to driving across the junction and then suddenly decelerate due to dawdling (sigma > 0).\n\nI see 2 ways to deal with this issue:\n- add simulation parameters to control the safety margins while comitted / uncomitted (MSLink.cpp:154 and accept occasional collisions if these parameters are set to tightly or low flow if set to conservatively\n- add an additional vehicle type parameter sigmaCritical (or somesuch) to use during critical situations. In my opinion this should default to 0 because people tend to concentrate during critical maneuvers\n\ndiscuss!", 
    "reporter": "namdre", 
    "cc": "behrisch,dkrajzew", 
    "resolution": "fixed", 
    "_ts": "1360925417000000", 
    "component": "simulation general (micro)", 
    "summary": "collisions because vehicles dawdle on the junction", 
    "priority": "major", 
    "keywords": "", 
    "time": "2013-02-12T16:56:43Z", 
    "milestone": "0.17.0", 
    "owner": "", 
    "type": "defect"
}

[behrisch]

@bjhend commented:

The second suggestion seems reasonable to me, because I guess it makes the simulation more realistic.

However, I'd like to suggest another solution, although it will probably be more work to implement it: For each junction set up a list of conflicting internal lanes and only allow vehicles to enter an internal lane if all conflicting internal lanes are empty. Note, that being in conflict is not a transitive relation. If lane A conflicts with B and B with C, it does not necessarily mean that A and C are conflicting.

This handling of conflicting lanes may help to simulate a behavior which is illegal, but which I've observed quite often: Drivers enter a junction on green light, although it is visibly occupied such that they cannot cross. (Sometimes I've seen drivers honking while doing that as if honking could cause a SUMO-like teleportation.)

[behrisch]

• @namdre commented:

fixed in 261c052 (aka r13351) with normal car following rules

• @namdre changed resolution from "" to "fixed"
• @namdre changed status from "new" to "closed"