  Solving the road congestion problem is one of the most pressing issues in
moderncities since it causes time wasting, pollution, higher industrial costs
and huge roadmaintenance costs. Advances in ITS technologies and the advent of
autonomousvehicles are changing mobility dramatically. They enable the
implementation of acoordination mechanism, called coordinated traffic
assignment, among the sat-navdevices aiming at assigning paths to drivers to
eliminate congestion and to re-duce the total travel time in traffic networks.
Among possible congestion avoidance methods, coordinated traffic assignment is
a valuable choice since it does not involvehuge investments to expand the road
network. Traffic assignments are traditionally devoted to two main perspectives
on which the well-known Wardropian principlesare inspired: the user equilibrium
and the system optimum. User equilibrium is a user-driven traffic assignment in
which each user chooses the most convenientpath selfishly. It guarantees that
fairness among users is respected since, whenthe equilibrium is reached, all
users sharing the same origin and destination willexperience the same travel
time. The main drawback in a user equilibrium is thatthe system total travel
time is not minimized and, hence, the so-called Price ofAnarchy is paid. On the
other hand, the system optimum is an efficient system-wide traffic assignment
in which drivers are routed on the network in such a waythe total travel time
is minimized but users might experience travel times that arehigher than the
other users travelling from the same origin to the same destina-tion affecting
the compliance. Thus, drawbacks in implementing one of the two assignments can
be overcome by hybridizing the two approaches aiming at bridging users'
fairness to system-wide efficiency. The survey reviews the state-of-the-art of
these trade-off approaches
