[sumo-user] How to make car following less safe?

[grimm <jan-grimm@xxxxxx>]

Hi there,

a question on the car-following parameter apparentDecel: I've been trying to change apparentDecel to values lower and higher than decel in order to adjust car following towards more risky and safer driving, respectively. While setting apparentDecel higher than decel (e.g. 1.1 times decel for each vehicle type), I indeed see a decrease in small time gaps, indicating safer driving. On the other hand, with lower apparentDecel (ranging down to 0.7 times decel), there is no difference (see chart below). Other parameters remain unchanged, mostly at their default values (except for speed distribution and lengths). I'm using the default car following and lange changing models with SUMO 1.6.0. My simulation scenario is a motorway section.


The following image shows the impact of the apparentDecel/decel ratio (called sensitivity factor) on the mean individual braking time risk (IBTR) in a motorway section, which increases with more frequent too-low time gaps.

It appears that the car following model prevents this kind of unsafe driving, using decel of the preceeding vehicle instead of apparentDecel, although the documentation on https://sumo.dlr.de/docs/Simulation/Safety.html states otherwise. Is that possible?


My goal is not necessarily to cause accidents, but to decrease time gaps to a slightly unsafe level. Thus, I wouldn't disable the safety checks in car following. The only other way to provoke more risky car following would be to decrease tau slightly below action step length. However, this quickly leads to large numbers of emergency braking maneuvers.


Is there any other way to get higher numbers of risky time gaps I haven't thought of yet? (Hints on literature sources also appreciated)


Thank you very much!
Kind regards
Jan

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