The roll-over of the tractor-semi-trailer units is a spectacular
road accident relatively specific to this type of vehicle,
especially in obstacle avoidance maneuvers.
Different mathematical models were established to determine the
transversal dynamics of the tractor-semi-trailer unit.
At the same time, dynamical tests on the road site permitted us
to quantify the variables of interest, and to adapt the models.
We used these models to design modifications for the tractor and
the semi-trailer in order to increase significantly the roll-over
threshold.
One experimental tractor and one experimental semi-trailer with
adjustable parts were built and tested on road site.
These experimental units are able to realise a transversal limit
acceleration of 5 m/s2, this limit being 3.5m/s2 for the
reference unit. On other criteria of road handling, the gain is
sensible and very positively felt by drivers.