  Truck drivers are required to stop and rest with a certain regularity
according to the driving and rest time regulations, also called
Hours-of-Service (HoS) regulations. This paper studies the problem of optimally
forming platoons when considering realistic HoS regulations. In our problem,
trucks have fixed routes in a transportation network and can wait at hubs along
their routes to form platoons with others while fulfilling the driving and rest
time constraints. We propose a distributed decision-making scheme where each
truck controls its waiting times at hubs based on the predicted schedules of
others. The decoupling of trucks' decision-makings contributes to an
approximate dynamic programming approach for platoon coordination under HoS
regulations. Finally, we perform a simulation over the Swedish road network
with one thousand trucks to evaluate the achieved platooning benefits under the
HoS regulations in the European Union (EU). The simulation results show that,
on average, trucks drive in platoons for 37% of their routes if each truck is
allowed to be delayed for 5% of its total travel time. If trucks are not
allowed to be delayed, they drive in platoons for 12% of their routes.
