Eclipse SUMO is an open source, highly portable, microscopic and continuous traffic simulation package designed to handle large networks. It allows for intermodal simulation including pedestrians and comes with a large set of tools for scenario creation.
In the fixed instances, the entering vehicle was at fault. In the remaining instances of emergency braking it appears that the changing vehicle is to blame.
after lane changing, a new link leader is found which triggers emergency braking without warning (-8m/s^2) and this causes the follower to collide.