final double meOldAcc = me.calcAccModel(currentLaneSegment, null);
// old situation for old back
// in old situation same left lane as me
final Vehicle oldBack = currentLaneSegment.rearVehicle(me);
final double oldBackOldAcc = (oldBack != null) ? oldBack.calcAccModel(currentLaneSegment, null) : 0.0;
// old situation for new back: just provides the actual left-lane situation
final double newBackOldAcc = (newBack != null) ? newBack.calcAccModel(newLaneSegment, null) : 0.0;
// new situation for new back: